Submitted by brad on Mon, 2009-11-30 15:42.
It was over 5 years ago that I blogged about a robot that would travel in front of a train to spot cars stuck on the tracks in time to stop.
I recently read a local story about an RV that was demolished while stuck on the tracks here. The couple had time to talk to 911, who told them to get out, and it’s not clear from the story but it seems like a moderate amount of time may have passed (a couple of minutes) before their RV was smashed.
Here’s what should happen, and perhaps it does happen in some places:
- The 911 service should receive GPS and cell tower location on the caller. The moment the caller indicates they are stuck on the tracks, the 911 operator should push a button which figures out which tracks it might be and which trains might be approaching that crossing.
- Ideally trains are reporting their location with GPS as some do, but schedules can be used, or all trains anywhere near the area can be alerted.
- Signal lights close to the crossing should immediately go red, and cell phones of operators on the relevant trains should be called, and the computer or 911 operator can indicate which crossing is blocked. If the engineer is approaching that crossing they can emergency brake.
This can be enhanced a few ways:
- Each crossing can have a big sign, “If stuck, get out of vehicle immediately, clear track (show direction) and call 911, and give this crossing number NNN.” The crossing number would work even if GPS and cell towers don’t locate the crossing.
- Alternately, there could be a 10 digit phone number, different for each crossing. There is, however, some risk of abuse and false reports. You don’t want a war dialing telemarketer to stop trains. An operator may still need to confirm.
- As noted, the sign should try to tell people to clear to the area slightly “upstream” (ie. towards the oncoming train, but not on the tracks, obviously.) That’s because when the train hits the car it throws it sideways and forward, never backwards along the path the train came from.
- If you don’t see or hear a train, it makes slight sense to get out and call while walking so the call comes sooner. If you can see the train they can see you and it’s probably too late anyway. But human safety is more important.
- The trains may have another way to reach the engineer, such as a private radio system, but just having a cell phone on each train (plus knowing trains staff personal cell phones and calling all of them) seems like a quick and easy solution. The cell in the train can have a very loud and flashing ringer, especially if it’s an emergency call.
It takes a long time to stop a train, but I bet most vehicles that get stuck on the tracks are stuck minutes before the train comes.
Submitted by brad on Thu, 2009-11-19 17:45.
I struck a nerve several years ago when I blogged about the horrible beep-beep noise made by heavy equipment when it backs up. Eventually a British company came up with a solution: a pulsed burst of white noise which is very evident when you are near the backing up vehicle but which disperses quickly so it doesn’t travel and annoy people a mile away as the beeps do.
Now I am seeing more and more suggestions that electric cars, which run quite silently when slow, make some noise for safety. This is fine, but there are also suggestions that there will be music and vanity noises, like ringtones or “cartones.” I can certainly see why this would appeal to people. (Already many think that their car is the place to play mind-numbing bass to announce musical taste to all others on the street.) There are even proposed laws.
While the cartones would be quieter than the backup beep or the heavy bass, I really fear that people will overdo what they think is the purpose — being attention grabbing. They will want to distract, and that will create a cacophony on the roads. It’s hard to make sounds that are meant to be attention grabbing (or vanity oriented) not travel beyond the range that you need them for safety.
I don’t want to imagine what it might be like living as I do with a 3-way stop outside my window, with each car singing a different tune or strange noise every time it slows down and starts up again. Who will want to live near intersections or parking lots?
I have a few proposals:
- Like the beep-beep solution, use white noise that just doesn’t travel very far, but is easily noticed when close.
- Use natural sounds, like waves crashing, birds chirping, wind blowing. We are tuned to hear those sounds in an otherwise silent environment, but our brains also can easily ignore them in background form.
- Do indeed tune the volume based on ambient noise. This is suggested in the O’Reilly article linked above. They propose it to be loud enough. It should also be quiet enough.
- Don’t do it at a speed where the tires and wind and electric motors are making enough noise already.
- As robocar sensors become more common, such as LIDAR and radar, only make the noise when there are people who might come in contact with the vehicle. Otherwise, be silent.
- Since robocars will not hit people in any normal operation, even people who don’t know they are there, such vehicles need not make any noise. HOwever, if they see a human or anything else on a collision course, let them make a more loud and useful noise that really gets attention, like a burst of white or pink noise, or even a horn if they ignore that. Start quiet, get louder if it is not reacted to in a human reaction time.
Let’s not give up on this opportunity to return peace to our public spaces as electric cars and robocars become popular.
Submitted by brad on Wed, 2009-09-09 11:40.
After every RV trip (I’m back from Burning Man) I think of more I want RVs to do. This year, as we have for many years, we built a power distribution system with a master generator rather than having each RV run its own noisy, smelly and inefficient generator. However, this is expensive and a lot of work for a small group, it is cheap and a lot of work for a larger group.
There’s been a revolution in small generator design of late thanks to the declining cost of inverters and other power conversion. A modern quality generator feeds the output of its windings to circuits to step up and step down the voltage to produce the required power. The output power is cleaner and more stable, and the generator is spun at different RPMs based on the power load, making it quieter and more efficient. With many models, you can also combine the internal output of two generators to produce a higher power generator.
RVs have come with expensive old-style generators that are quieter than cheap ones, and which produce better power, but today they are moving to inverter generators. With an inverter generator, it’s also possible to draw on the RV batteries for power surges (such as starting an AC or microwave) beyond what the generator can do.
I’m interested in the potential for smarter power, so what I would like to see is a way for a group of RVs with new generation power systems to plug together. In this way, they could all make use of the power in the other vehicles, and in most cases only a fraction of the generators would need to be running to provide power to all. (For example, at night, only one generator could power a whole cluster. In the day, with ACs running, several would need to run, but it would be very unlikely to have to run all, or even 75% of them.) read more »
Submitted by brad on Tue, 2009-08-25 23:39.
RVs all have a fresh water tank. When you rent one, they will often tell you not to drink that water. That’s because the tanks are being filled up in all sorts of random places, out of the control of the rental company, and while it’s probably safe, they don’t want to promise it, nor disinfect the tank every rental.
I recently got a small “pen” which you put in a cup of water and it shines a UV light for 30 seconds to kill any nasties in the water. While I have not tried to test it on infected water, I presume that it works.
So it seems it makes sense to me to install this sort of UV tube in the fresh water tank of RVs. Run it from time to time, and particularly after a fill, and be sure the water is clean. Indeed, with an appropriate filter, and a 2nd pump, such an RV could happily fill its water tank from clear lakes and streams, allowing longer dry camping which should have a market. Though of course the gray/black water tanks still will get full, but outside showers and drinking do not fill those tanks.
A urination-only toilet could also be done if near a stream or lake.
Submitted by brad on Mon, 2009-02-09 20:29.
Recently, some prosecutors, in efforts to crack down on drunk driving, are pushing for murder convictions. This is happening in the case of really blatant disregard on the part of the drunk drivers — people with multiple DUIs getting smashed, going out, and killing.
In watching coverage of this trend, over and over again I heard it said that the killer’s sin was “getting behind the wheel when drunk.” And that is in fact what we punish with DUI laws. Because so many people have done it (without killing anybody) there is surprising sympathy for the drunk drivers — there but for the grace of god go I.
But is that the right sin? That decision is always made once the person has impaired judgement. Something to me seems wrong about punishing a decision made when one has lost the ability to make good decisions. While I don’t drink, and have no sympathy for the actions of drunks, I think the real transgression comes much earlier.
The real transgression is allowing yourself to get impaired in circumstances where you would then be sufficiently likely to make deadly wrong decisions. A simple example of this would be having enough alcohol to move from sober to drunk when you have your car with you and plan to drive home. Of course, many people in that situation will do the right thing, and still be clear enough to know they should get a cab home, and then come back to pick up their car later. But of course, many don’t. And worse, there is often an incentive not to — such as paying for two taxi fares, and dealing with the car’s location becoming a no-parking zone in the morning.
I believe people should be punished for risky decisions they make while sober, more so than ones they make while drunk. It should be expected that people will make poor decisions and take unacceptable risks when drunk. That is what impairment means. It is the decisions they make when sober, when they know right from wrong, that the law should punish.
Now let me describe how this might work in theory, and then discuss the harder question of making it work in practice.
The simplest way to behave well is to never take your car to go drinking. That car parked outside is too much temptation once you are drunk. And this is what the designated driver concept is about. To get more specific, you must not take the drinks that make you impaired without first, while still not so impaired, making plans to get home so you have no temptation to drive your car. This can include arranging a ride with a sober person, pre-contracting with a taxi company for later pickup, or putting your car keys into escrow.
Car key escrow, for example, would involve giving the keys to a friend or the bartender, who will not return them to you until you are sober. A high-tech version might be a simple lockbox. You can put your keys in the lockbox (provided by a responsible bar) and can only get them out by blowing into the box with alcohol below the limit. The act of escrow, taken while sober, makes you legal. The act of drinking beyond your limit without making alternate plans is the immoral act. Having any recorded plan for getting home — cab, designated driver, transit ticket, keys in escrow — is enough to be acting morally.
Now how to enforce this? Well, we can’t really have police coming into bars, and asking all patrons who are beyond the limit to prove they made alternate plans. Police could check inebriated people leaving bars, but don’t typically have the time for this. If this sort of rule is to be enforced, it would have to be through legal liability on those who serve alcohol (bars, party hosts) to assure none of their guests go beyond the limit without plans, or at least the easy ability to make plans. (Cheap key lockboxes might help in this area.)
And of course, anybody who did drive drunk would be guilty since they obviously didn’t make adequate plans. This approach would simply expand the culpable act to the broader situation of having deliberately (while sober) put yourself in a situation where this has a real chance of taking place.
There are problems of course. Often “guests” come to parties uninvited and get drunk. We’ve all had a fairly drunk person at a party we barely know. Or we may not know the drinking habits of the friends we do invite. Bartenders deal with people arriving who already got sauced at another bar and just have the last few drinks before they drive in the 2nd bar. We want people to act responsibly, not have to go overboard and be paranoid about each guest. Ideally we want the full weight of the law to fall on the sober person who got drunk while his or her car was outside.
One unconnected option might make sense. Parking laws might be changed to let you get out of certain kinds of parking tickets if you can show proof you took an alternate way home because you are drunk. Taxi drivers who take drunks home could issue such a dated receipt. Friends could testify under oath that they drove you home because you were drunk. This might make people more willing to leave cars behind in certain areas. It would have to be clear what those areas were (for example, parking that was free at night but becomes metered or prohibited at 7am) so that the parking does not become a problem. Still the extra parked cars are a better thing to have than cars with drunks behind the wheel.
Submitted by brad on Mon, 2008-11-10 21:53.
Here are some notes based on my recent trip to Finland, Sweden and Russia. Not about the places — that will come with photos later — but about the travel itself.
The ferries between Helsinki and Stockholm are really cruise ships. It takes about 16 hours and is a very popular method of travel between the cities, especially for families. There is no really practical land route, and the competition keeps the prices of these things down. In addition, they play tricks to allow duty free shopping, and unlike many duty free shops which are just ripoffs, these ones are competitive and do a brisk business. I’m told they are also party boats, but due to jet lag I was asleep not long after the Smörgåsbord. Unlike most cruise ships, these have almost nothing included, not the sauna, not the food and probably not even the mandatory showing of Abba’s “Mamma Mia.”
Because it the boat left at sunset and I planned to be awake and above at sunrise for photography of the Swedish Archipelago, and the moon was new, I decided there would be nothing to see, and I took an inside cabin. I was surprised to learn that, even though I knew it was dark and largely featureless outside, it bothered me to be in the sealed room. I reiterate my call that ship inside cabins come with a TV showing a closed circuit view of the outside in the correct direction. If they are not ready to do that (this ship didn’t even have TVs) I think a light behind the curtains of the fake window which simulates, based on just the clock, what the light should be like outside, would actually still be a positive step.
Or, failing that, if they put internet in the rooms, people could display the closed circuit video on the screen they brought with them…
On a ship like this, the shower takes up a lot of a very small room while being very cramped anyway. While most people want a toilet in their room, some communal locker room showers might make sense for preserving space. Of course, you still need a lot of them as demand comes at the same time, but not quite as many.
I think I’ll go back to a window for my next cruise cabin. But not a balcony. I have found that when I’ve had a balcony I sat on it for an hour of the entire week, and it took a lot of space out of the cabin.
The nice thing about the overnight cruise, of course, is that it made the trip between cities happen at night, offering a near full day in each city on either end. The arrival is a bit late at 10am, but that time is spent on a cruise of the islands, which all Stockholm tourists want anyway. It made me wonder if it was possible to arrange that sort of travel among close coastal cities in the USA or Canada (Boston to DC?) but perhaps the seas are not as reliable. And of course there is the Jones Act.
For the tourist, it also means the cruise is one of your hotel nights, and it costs only a little more for two people than a typical Stockholm hotel.
Taxi in Stockholm
Arriving in Stockholm, I was advised I should take a cab to our hotel and it would cost under $20. I had to eat my own words about cab competition because I got into a predator cab in the line at the ferry terminal which charged 5 times the typical rates. A few blocks away we noticed the meter going up one SEK (13 cents) per second and asked the driver to stop. He got abusive and threatening, and with my luggage implicitly hostage, I paid $25 to be dumped on the street in the rain with 3 suitcases and no SEK. Turned out there was a subway stop not far away, though that’s no fun with lots of bags.
Turns out the cabs do have their prices on them in the window, and no Swede would hire such a cab, but tourists unaware of the system can be easy marks, so no surprise this cab was at the ferry terminal. I had written earlier that I don’t believe in the heavy Taxi regulation most cities have, though I had come so much to expect it I got burned. The main argument for the regulation is that you can’t shop while standing waiting to hail a cab, but I can now see another argument about it on taxis serving people who will not know the local markets.
Stockholm transit was quite good, and we got an unlimited pass so used it a lot, though in many cases a cab would have probably saved valuable time. But we were so burned by our first Stockholm taxi experience that we just never felt the desire to use one again until the trip to the airport, which we had the hotel arrange.
Transit in St. Petersburg
St. Petersburg transit is a very different experience. It’s cheap: Typical fare of 16-18 rubles (around 60 cents) for official transit, 23 rubles for private buses that are more common. It’s very heavily used. Oddly, there did not appear to be transfers. If you wanted to change from trolley to bus, you seemed to pay again, or so our host told us. While at the low price this should not be a problem, it does mean you’re more likely to walk if you only have to go one or two stops on the 2nd leg.
The subway (which is quite grand, a Soviet showpiece) was packed to the gills on Sunday afternoon. We didn’t ride it during rush hour, and I’m glad. The subway isn’t actually terribly useful for the city core where the tourist sites are, though there happened to be a stop near our nice B&B.
Transport to/from the airport is another story, with most services seeming to run 40 to 60 Euros, though our host arranged a private car (by which I mean, just some guy’s Volga) for 30 Euros. We didn’t try it, but there is also an ad-hoc private taxi system. Stick out your arm and a private citizen will come pull over and negotiate a price, if they are going your way.
As noted, our driver had a Volga, but generally the streets are full of foreign cars. The car everybody wants is a Corolla. Ford is making big inroads too, along with Hyundai.
Finnair is charging for soft drinks on board, that trend is growing. ?????? (Rossiya) airlines still uses paper tickets, that was strange and frustrating. United Airlines won’t let a Premier member upgrade on a United Flight if their ticket came from Lufthansa (which I needed to do to make the Finnair connection as UA doesn’t partner with them.)
When I got my HTC Mogul phone, it had a GPS inside it, but the firmware didn’t enable it. So while in Germany in January, I used an external bluetooth GPS which worked OK, if being a bit silly. After I got back I got a phone firmware upgrade, which enabled the internal GPS, which has been very handy since then. When I got back to Europe I discovered two annoying things:
- While the GPS does use assisted GPS from the cell towers to work faster in the USA, it is a full GPS able to work away from them. But not in Europe, where it refused to work, even when it could see 5 or 6 satellites. Some report getting the phone GPS to wake up after 10-20 minutes but it never did for me.
- Alas, when they enabled the internal GPS, they disabled the ability to use an external bluetooth GPS through the official WINCE GPS API. So I was worse off than before.
- While a few programs could use the external GPS because you could manually configure them to use a different port, the offline map program I had downloaded could not. This had a real cost, as I ended up taking a few wrong turns and taking a few wrong street cars without knowing which direction I was going.
So brickbats for Sprint/HTC for this bizarre configuration, and I hope they fix it.
Submitted by brad on Tue, 2008-10-14 21:00.
I’ve written a few times about the “Selfish Merge” problem. Recently, reading the new book Traffic: Why We Drive the Way We Do by Tom Vanderbilt, I came upon some new research that has changed and refined my thinking.
The selfish merge problem occurs when two lanes reduce to one. Typically, most people try to be “good” and merge early, and that leaves the right lane, which is ending, mostly vacant. So some people zoom ahead of everybody in the right lane, and then merge at the very end. This is selfish in the sense that butting into any line is selfish. Even if overall traffic flow is not reduced (and even if it is increased) the person butting in moves everybody back one slot so they can get ahead by many slots. This angers people and generates more counter-productive behaviour, including road rage, and attempts to straddle the lanes so that the selfish mergers can’t move up to the merge point.
In Traffic, Vanderbilt writes of surprising research that changed his mind, which showed that, in simulations, some merging forms provided up to 15% more traffic throughput than proper attempts at a zipper merge. In particular, a non-selfish merge fully using the vanishing lane worked better than the typical butt-in situation described at the top.
In this merge, which I’ll call the “slow and fair merge,” drivers are told to use both lanes up to the merge-point, and then to fairly “take their turn” at the merge point entering the continuing lane. Nobody is selfish here, in that nobody butts ahead of anybody else, but both lanes are fully utilized up to the merge point.
This problem is complex, I believe, because there is a switch-over point, which I call the “collapse” point. This is the point at which the merge flow becomes high enough that traffic collapses to “stop and go” mode, before and at the merge-point. Before that point, in lighter traffic, there is little doubt (for reasons you will see below) that the “cooperating fast zipper” merge results in the best traffic flow. In particular, there are traffic volumes where you could either have cooperating zipper or “slow and fair” but cooperating zipper would do a fair bit better. There are also traffic volumes where cooperating zipper just isn’t possible any more, and we will either have “slow and fair” (which has the best volume) or “selfish merge” which has a worse volume.
Real world experiments show different results from the theoretical. In particular, many drivers, used to the anarchic selfish-merge approach, don’t understand fair and slow, even when signs are explicit about it, and so they resist using both lanes and try to merge early. They also try to straddle, devolving to selfish merge. An experiment with digital signs which changed from advising drivers to zipper-merge in light traffic to advising “use both lanes” and “merge here, take your turn” in heavier traffic was disobeyed in fair and slow mode by too many drivers. The experiment ended before people could learn the system. read more »
Submitted by brad on Thu, 2008-10-09 12:26.
Ford is making a new car-limiting system called MyKey standard in future models. This allows the car owner to enable various limits and permissions on the keys they give to their teen-agers. Limits included in the current system include an 80 mph speed limit, a 40% volume limit on the stereo, never-ending seatbelt reminders, earlier low-fuel warnings, audio speed alerts and inability to disable various safety systems.
My reaction is of course mixed. If you own something, it is reasonable for you to be able to constrain its use by people you lend it to. At the same time it is easy to see this literal paternalism turn into social paternalism. While it’s always been possible to build cars that, for example, can’t go over the speed limit, it’s always been seen as a “non-starter” with the public. The more cars that are out there which have governors on them, the more used to the idea people will get. (“Valet” keys that can’t go over 25mph or open the trunk have been common for some time.)
This is going to be one of the big questions on the path to Robocars — will they be able to violate traffic laws at the command of their owners? I have an essay on that coming up for the future, where I will also ask how much sense traffic laws make in a robocar world.
The Ford key limits speed to 80mph to allow the teen to pass on the highway. Of course on some highways here you could not go in the fast lane with that governor on, which probably suits the parents just fine. What they probably want would be more a limit on average speed, allowing the teen to, for short periods, burst to the full power of the car if it’s needed, but not from a standing start, and of course with advanced warning when the car has gone too fast too long to give a chance to safely slow down.
The earlier low-gas warning is just silly. The earlier you make a warning, the more you teach people to ignore it. If you have an early warning (subtle) and then a “this time we really mean it” warning most people will probably just use the second one. Many cars with digital fuel meters refuse to estimate fuel left below a certain amount, because they don’t want to be blamed for making you think you have more gas than you do. So they tell you nothing instead, which is silly.
What might make more sense would be the ability to make full use of speed, but the threat of reporting it to mom & dad if it’s over-used. (Such a product would be easy to add to existing cars, I wonder if anybody has made a product like that?) Ideally the product would warn the teen if they were getting close to the limit, to let them govern themselves, knowing that they would face a lecture and complete loss of car privileges if they go over the limitations.
On one hand, this is less paternalistic, because it does not constrain the vehicle and teaches the child to discipline themselves rather than making technology enforce the discipline. On the other hand, it is somewhat Orwellian, though the system need not report the particulars of the infringement, just the fact of it. Though we can certainly see parents wanting to know all the details.
Of course, we’ll see a lot more of that sort of surveillance asked for. Track-logs from the GPS in fact. Logging GPSs that can be hidden in cars cost only $80, and I am sure parents are buying them. (I have one, they are handy for geotagging photos.) We might also start seeing “smart” logging systems that measure speed infractions based on what road you are on. Ie. 80mph not near any highway is an infraction but on the highway it isn’t.
I doubt we’ll be able to stop this sort of governing or monitoring technology — so how can we bend it to protect freedom and privacy?
Submitted by brad on Mon, 2008-06-09 20:11.
As part of my research into robotic cars, I’ve been studying the energy efficiency of transit. What I found shocked me, because it turns out that in the USA, our transit systems aren’t green at all. Several of the modes, such as buses, as well as the light rail and subway systems of most towns, consume more energy per passenger-mile than cars do, when averaged out. The better cities and the better modes do beat the cars, but only by a little bit. And new generation efficient cars beat the transit almost every time, and electric scooters beat everything hands down.
I encourage you to read the more detailed essay I have prepared on whether green U.S. transit is a myth. I’ve been very surprised by what I’ve found. It includes links to the sources. To tease you, here’s the chart I have calculated on the energy efficiency of the various modes. Read on, and show me how these numbers are wrong if you can!
I have added a follow-up post on the comparison between lots of small personal ultralight vehicles and larger shared transit vehicles.
Note: If you want to comment on the cyclist figure, there is different thread on the fossil fuel consumption in human food which details these numbers and invites comments.
Submitted by brad on Tue, 2008-03-25 18:47.
Note to new readers: This article explores the consequences of using so much fuel to produce our food. If you come out of it thinking it’s telling you to drive rather than get some exercise, you didn’t read it! But if you like surprising numbers like this, check out the rest of my Going Green section and other sections.
In my growing research on transportation energy economics, I’ve come upon some rather astonishing research. I always enjoy debates on total cost analysis — trying to figure out the true energy cost of things, by adding in the energy spent elsewhere to make things happen. (For example, the energy to smelt the metals in your car adds quite a bit to its energy cost.)
Humans are modestly efficient. Walking, an average person burns about 100 Calories per mile at 3mph, or 300 per hour, while sitting for the same hour burns around 80 Calories just keeping you warm. In other words, the walking 3 miles uses about 220 extra Calories. Calories are kilocalories, and one Calorie/kcal is about 4 BTUs, 4200 joules or 1.63 watt-hours.
While walking 1 mile burns an extra 74 Calories, on a bicycle we’re much better. Biking one mile at 10mph takes about 38 extra calories over sitting. Again, this is the extra calories.
A gallon of gas has about 31,500 Calories in it, so you might imagine that you get 815 “mpg” biking and 400 “mpg” walking. Pretty good. (Unless you compare it to an electric scooter, which turns out to get the equivalent of 1200 mpg from pure electricity if you allow the same perfect conversion.)
But there’s a problem. We eat, on average about 2700 Calories/day in the USA, almost all of it produced by agribusiness. Which runs on fossil fuels. Fossil fuels provide the fertilizer. They run the machines. The process and transport and refrigerate the food. In many cases our food — cows — eats even more food produced with very high energy costs.
I’ve been digging around estimates, and have found that U.S. agriculture uses about 400 gasoline-gallon equivalents per American. Or 1.1 gallons per day, or about 10 Calories (40 BTU) from oil/gas for every Calorie of food. For beef, it’s far worse, as close to 40 Calories of oil/gas (160 BTU) are used to produce one Calorie of beefy goodness.
You can see where this is going. I’m not the first to figure it out, but it’s worth repeating. Your 3 mile walk burned 220 extra Calories over sitting, but drove the use of 2,200 Calories of fossil fuel. That’s 1/14th of a gallon of gasoline (9oz.) So you’re getting about 42 miles per gas-gallon of fossil fuel.
If you eat a lot of beef or other livestock, and want to consider your incremental food as having come from beef, it’s around 10 miles per gallon. A Hummer does better!
So yes, if you drive your Prius instead of walking it’s going to burn less fossil fuel. If 2 people drive in a more ordinary car it’s going to burn less fossil fuel than both of them walking.
Biking’s better. The average-diet cyclist is getting 85 miles per gallon of fossil fuel. Still better for 2 to share a Prius. The beefeater is, as before only 1/4 as good. At 21mpg he’s better than a Hummer, but not that much better.
This is a fuel to fuel comparison. The fuel burned in the cars is the same sort of fuel burned in the tractors. It has extra energy costs in its extraction and transport, but this applies equally to both cases. And yes, of course, the exercise has other benefits than getting from A to B. And we have not considered a number of the other external costs of the vehicle travel — but they still don’t make this revelation less remarkable. (And neither does this result suggest one should not still walk or bike, rather it suggests we should make our food more efficiently.)
And no, picking transit isn’t going to help. Transit systems, on average, are only mildly greener than cars. City buses, in fact, use the same energy per passenger mile as typical cars. Light rail is sometimes 2 and rarely even 3 times better than cars, but in some cities like San Jose, it uses almost twice as much energy per actual passenger than passenger cars do.
Taking existing transit vehicles that are already running is green, of course, but building inefficient lines isn’t.
Many people take this idea as a condemnation of cycling or exercise. It isn’t. Cycling is my favourite exercise. It is a condemnation of how much fossil fuel is used in agriculture. And, to a much lesser extent, a wakeup call to people who eat the average diet that they can’t claim their human-powered travel as good for the planet — just good for them. What would be good for the planet would be to eat a non-agribusiness diet and also walk or bike. How your food is farmed is more important though, than where it comes from. It’s the farming, not the shipping, that’s the big energy eater.
Obviously if you were going to need the exercise anyway, doing it while getting from A to B is not going to burn extra oil. Human powered travel well above the need to exercise is the only thing that would hurt, if fueled by U.S. agriculture. And eating a high calorie diet and not exercising would be just as bad.
What’s not wrong with these numbers
As I note, since most of us need to exercise anyway, this is not at all a condemnation of walking and cycling, but rather of the amount of fossil fuel that agriculture uses. However, a lot of people still find faults with this analysis that I don’t think are there.
- No, it doesn’t matter that making the fuel costs energy. It’s (roughly) the same fuel going into the tractors as going into the gas tanks. We’re comparing fuel in tank to fuel in tank. But if you really want to factor that in, about 82% of well energy makes it to the gas tank of the car or tractor.
- Yes, I do account for the fact that just eating or sitting consumes calories. This calculation is based on the extra calories that biking or walking take, compared to sitting in a car. The base “keep you alive” calories are not counted, but they do require more fossil fuel to create.
- I don’t include the energy required to make a car, which ranges from 25% (Prius) to 7% (Hummer) of its lifetime energy usage. However, most cyclists and pedestrians still own cars, so this is still spent if it sits in the garage while you walk. And while a 2000lb car may take 60-100 times as much energy to make as a 30lb bike, this is not so large a difference if expressed per lifetime vehicle-mile.
- This is based on the USA averages. Of course different food means different results, but doesn’t change this story, which is about the average eater.
- I don’t include the energy needed to build roads for bikes, cars and food delivery trucks. The reality is, we’re not going to build fewer roads because people take some trips walking for exercise. Nor are people going to not buy a car because they do that.
Submitted by brad on Mon, 2008-02-11 21:55.
Rental car companies are often owned by car manufacturers and are their biggest customers. As cars get more and more computerized, how about making rental cars that know how to personalize to the customer?
When Hertz assigns me a car, they could load into its computer things like the dimensions of my body, so that the seat and mirrors are already set for me (simply remembered from the last time I rented such a car, for example.) If I have a co-driver, a switch would set them for her. The handsfree unit would be paired in advance with my bluetooth phone.
The prep crew would have made sure there was a charger for our cell phones and other mobile devices in the car, at least for the major charger types such as USB and mini-USB, which should become standard on car dashes soon anyway. Perhaps there could even be a docking cradle.
The radio stations should be set to how I set them the last time I was in the rental town. If this is unknown, stations of the formats I like should be on the buttons I use. (Button 1 for NPR/CBC, Button 2 for Jazz, Button 3 for Rock, Button 4 for Classical, Button 5 for Traffic etc.) Or if satellite radio is used, settings for that could be preserved all over the world.
Any other car settings should be remembered and re-loaded for me.
All cars will have a GPS soon of course, but it should also be a bluetooth one that will transmit to my laptop or PDA if I want that. While I don’t want the company keeping a log of where I drive, it would be nice if I could specify destinations I plan to visit on the rental car web site when I reserve the car, and these would be pre-loaded into the GPS. And perhaps it could also be trained to my voice. For cars with a keycode entry, the code could be “my” keycode.
In other words, every possible thing you can easily customize about your own car should be available for loading into a rental car, to make it seem more like your car. And, of course, if you already drive such a car, it could very well be your car. (Though in the USA, because the rental car companies have these close relationships with Ford, GM and the like, don’t expect that if you drive an imported car.)
Is it that much time to set up a car when you rent it? Not really. But this is just something nice for the future. Regular readers will know I predict that as cars drive themselves, we will far more routinely use hired vehicles, and this sort of “make it mine” technology will become more important then.
Submitted by brad on Fri, 2007-09-14 12:24.
I wrote earlier this week about selfish merging and traffic jams and this prompted some to ask if the selfish merge is really selfish. Update: There is more and new thinking in this later post on selfish merge being not so selfish.
There are two forms in which it is selfish. At its most basic, it is barging into line. A series of cars is traveling the road, and one car, who is behind all the others, waits for them to merge out of the vanishing lane, then zooms ahead of all of them, and get somebody up front to let them in where the merge has made things stop-and-go. 100 people behind the merger are delayed 5 seconds each, and he gains 500 seconds compared to joining the back of the line. That’s if you presume it’s a zero sum situation.
However, I believe it is worse than zero-sum, for a couple of reasons. A typical highway lane can handle 2,000 cars/hour, but only about 1,000 if traffic slows to a crawl. Cars that merge while traffic is still flowing are less likely to cause the collapse than those who attempt to merge from a stopped position at the end of the vanishing lane. It starts when somebody slows to let them in, or they barge in forcing somebody to brake.
Now if two lanes able to carry 2,000 cars/hour merge to one, we can only have smooth flow if there are in fact only 1,000 cars per hour (or fewer, since heavy merging reduces capacity to about 1,500 cars/hour) in each lane. If input is within the output capacity of the continuing lane, we can do fine. However, if slowing to stop and go reduces the chokepoint to 1,000 cars per hour, we can only handle 500/cars/hour/lane or the jam backs up for a long distance. Once input exceeds the output capacity we must take more dramatic steps to stop a long traffic jam.
This is the theory that supports metering lights on highways. As long as the highway flows at good speed, its capacity is high and sufficient for the traffic. If it gets a burst of high-demand, it collapses into a traffic jam. Thus, for people waiting at metering lights, while they are annoyed at waiting, in fact because everybody is being metered they will get there faster than if they don’t wait. For the car at the “tipping point” it can be the case that if they wait, they will join a smooth traffic flow, but if they rush into traffic, they will be the straw that breaks the camel’s back and slows everybody, including themselves.
My proposal is similar to metering lights, except for a merge. Merging reduces lane capacity as cars must increase spacing to allow safe merging. Or they must stop entirely in a jam. If demand starts to exceed capacity, my proposal is to prohibit merging well down the highway. The cars in the continuing lane zoom through without merging using the full capacity of the lane. However, from time to time they must stop (creating a waiting line) to let the cars in the vanishing lane through, also at full speed without merging. The volume of cars through the chokepoint is what matters here, and if we can increase that to 2,000 cars/hour instead of 1,000 cars/hour, we will have a far shorter jam when there is no choice but to have a jam (ie. more than 2,000 cars/hour coming in.) And by encouraging cars to merge early, we can avoid a jam when we have less than 1,500 cars/hour coming in. When we have something in between, we introduce a hopefully short single pause but maintain a little under 2,000 in output capacity. We would need experimentation to learn what the output capacity is with metered stopping.
Submitted by brad on Mon, 2007-09-10 12:49.
I have written before about the selfish merge which is a tricky problem to solve. One lane vanishes, and the merge brings everybody to a standstill. Selfish drivers zoom up the vanishing lane to the very end and are let in by other drivers there, causing the backup. The selfish strategy is the fastest way through the blockage, yet causes the blockage.
My thinking on Burning Man Exodus made me wonder if we might have a robot signal drivers not with lights but with radio. At the merge point we would place a computer with a radio transmitter, and detectors to measure the speed of traffic in each lane. If traffic flowed at a good speed, it would do nothing. If traffic slowed, signs would light up saying “Tune to and Obey AM 1610. $500 fine for lane changing without clearance.”
The robot would be at the merge point, and also have traffic lights marked with lane numbers of names.
The radio robot would then move the lanes through the merge. The key is the robot can tell an entire lane to start moving slowly simultaneously, and to stop simultaneously, even over a longer distance. So it can command the left lane to start moving and the others to remain stopped and not to change lanes. When the left lane has emptied, it can command it to stop and the red light for that lane would go on (clearly visible at the merge point.) A camera could record anybody running the red light or changing lanes into that lane as it is emptying. As it is clearing, the radio voice can tell the next lane to prepare to move, and give it the green light and the verbal command to do so. Lower priority would be given to the lane that is vanishing and those stuck in it — they were supposed to do a nice zipper merge a mile back, and are only stuck in it because they didn’t do so. This means that zooming up in the vanishing lane becomes punished rather than rewarded, and as a result, this jam-clearing approach would be needed far less.
The system would have to be experimented with and tuned for the best results.
There is a problem that there has to be some point where the system starts, after which lane changes are forbidden. There is a risk that a jam could be created there rather than at the physical merge point, by people in the vanishing lane trying to get into to continuing lane. This is the parameter we would tune — how much punishment can we give the people who wait too long in the vanishing lane before they start creating a jam a bit further up the road? Perhaps no punishment is needed, just equal treatment.
Of course there are two types of merges. Some are temporary, due to construction. Others are permanent. I am primarily aiming at the temporary ones here though it’s possible that solutions could be found for permanent merge-jams. However, in permanent merges, drivers get to know the parameters and will try to game them. If we move where the merge is it’s hard not to simply move the jam.
There is also the question of the very few cars without radios, and those who can’t understand basic instructions in the languages given on the radio. (The instructions can be said in up to 3 languages, I would think.) Such drivers would have to just follow the other cars, which is doable, even if their reaction time will not be as quick. Drivers who can’t read the signs already face the risk of violating traffic laws, of course.
I also don’t know how much gain you get from everybody being able to stop and start at once on voice command. Obviously moving cars need wider spacing than stopped cars, so you can’t actually start everybody at once like a train. Still, I think it should be possible to drain a blockage faster with the combination of coordinated starting and nobody else being allowed to merge into the lane during the period.
It’s also possible the voice could tell cars in the vanishing lane to simultaneously enter the continuing lane once it has been cleared, but that requires a way to stop oncoming traffic from entering that lane during that process, and it’s easier if all equipment can be placed at the merge point.
Submitted by brad on Sat, 2007-06-16 11:54.
From time to time I come up with ideas that are interesting but I can't advocate because they have overly negative consequences in other areas, like privacy. Nonetheless, they are worth talking about because we might find better ways to do them.
There is some controversy today over whether driving while talking on a cell phone is dangerous, and should be banned, or restricted to handsfree mode. It occurs to me that the data to answer that question is out there. Most cars today have a computer, and it records things like the time that airbags deploy, or even in some cases when you suddenly dropped in speed. (If not, it certainly could.) Your cell phone, and your cell company know when you're on the phone. Your phone knows if you are using the handsfree, though the company doesn't. Your phone and cell company also know (but usually don't record) when you're driving and suddenly stop moving for an extended period.
In other words, something with access to all that data (and a time delta for the car's clock) could quickly answer the question of what cell phone behaviours are more likely to cause accidents. It would get a few errors (such as if the driver borrows their passenger's phone) but would be remarkably comprehensive in providing an answer.
But to gather this data involves way too many scary things. We don't really want our cars or phone companies recording data which can be used against us. They could record things like if we speed, and where we go that we don't want others to know about, and who we're talking to at the time, and much more.
In our quest for learning from private data, we have often sought anonymization technologies that can somehow collect the data and disassociate it from the source. That turns out to be very hard to do, often near impossible, and the infrastructure built for this sort of collection can almost always be trivially repurposed for non-anonymous use; now all that is needed is to flick a switch.
Now I do expect that soon we will see, after a serious car accident, attempts to get at this data on a case by case basis. The insurance companies will ask for cell phone records at the time of the accident, or data from the phone itself. We're already going to lose that privacy once there is an accident, thought at least case by case invasions don't scale. Messy problem.
Submitted by brad on Fri, 2007-04-13 19:48.
In many cities, the transit systems have GPS data on the vehicles to allow exact prediction of when trains and buses will arrive at stops. This is quite handy if you live near a transit line, and people are working on better mobile interfaces for them, but it's still a lot harder to use them at a remote location.
It would be nice to have a small internet appliance for shops, cafes and other hangouts that are short walks from transit stops. The appliance would be programmed with the typical walking time to the stop, and of course which stop to track. It would then display, on a small screen when a vehicle was coming, and how much time you had before you could walk easily, and then before you could run and make the train or bus.
Failing the live GPS data it could just work on schedules. It might make a low-key but audible noise as well. It need not have its own screen, if the place has a TV already it could do an overlay on that, though flat panel screens are now only about $100.
Some transit lines have placed expensive outdoor "next bus" signs on their stops and shelters for these systems, which is great, but in fact it might make more sense to put an appliance like this behind a local shop window, where it doesn't need to be outdoor rated, and pay the shopowner or local homeowner.
To turn this into a moneymaker, it could be combined with a system to sell transit tickets (presumably through the cash register.) This is a win for the transit system, since transit lines without controlled stations waste a lot of time as the driver collects change and tickets as people get on. People with a pre-paid, pre-timestamped ticket can get on quickly and don't need a transfer. This even works for systems with distance based pricing. I have often wondered why you don't see more selling of transit tickets at the shops around stops in order to save this delay. SF Muni went to "proof of purchase" instead of driver collected tickets so they could put ticket machines at busy stops to save the driver time, but they aren't everywhere.
For a cafe, it's a nice thing to do for customers, and even makes them more willing to stay, safe in the knowledge they can get their vehicle efficiently. A taxi-summoning function could also be added (press a button on the box to call a taxi) which could, in theory, also predict when the taxi will arrive since many of them have GPS networks now.
Submitted by brad on Wed, 2007-02-21 16:16.
Many cities (and airports) have official taxi monopolies. They limit the number of cabs in the city, and regulate them, typically by issuing “medallions” to cabs or drivers or licences to companies. The most famous systems are in London and New York, but they are in many other places. In New York, the medallions were created earlier in the century, and have stayed fixed in number for decades after declining from their post-creation peak. The medallion is a goldmine for its “owner.” Because NY medallions can be bought and sold, recently they have changed hands at auction for around $300,000. That 300K medallion allows a cab to be painted yellow, and to pick up people hailing cabs in the street. It’s illegal for ordinary cars to do this. Medallion owners lease the combination of cab and medallion for $60 to $80 for a 7-9 hour shift, I believe.
Here in San Francisco, the medallions are not transferable, and in theory are only issued (after a wait of a decade or more) to working cab drivers, who must put in about 160 4-hour shifts per year. After that, they can and do rent out their medallion to other drivers, for a more modest rental income of about $2,000 per month.
On the surface, this seems ridiculous. Why do we even need a government monopoly on taxis, and why should this monopoly just be a state-granted goldmine for those who get their hands on it? This is a complex issue, and if you search for essays on taxi medallions and monopoly systems you will find various arguments pro and con. What I want to get into here is whether some of those arguments might be ripe for change, in our new high-tech world of computer networks, GPSs and cell phones.
In most cities, there are more competitive markets for “car services” which you call for an appointment. They are not allowed to pick up hailing passengers, though a study in Manhattan found that they do — 2 of every 5 cars responding to a hail were licenced car services doing so unlawfully. read more »
Submitted by brad on Sun, 2007-01-28 17:33.
In the SF Bay Area, there are carpool lanes. Drivers of fuel efficient vehicles, which mostly means the Prius and the Honda Civic/Insight Hybrids can apply for a special permit allowing them to drive solo in the carpool lanes. This requires both a slightly ugly yellow sticker on the bumper, and a special transponder for bridges, because the cars are allowed to use the carpool lane on the bridge but don’t get the toll exemption that real carpools get.
I think this is good, as long as there is capacity in the carpool lane, because the two goals of the carpool lane are to reduce congestion and also to reduce pollution. The hybrids do the latter. (Though it is argued that hybrids do their real gas saving on city streets, and only save marginally on the highway, comparable to some highly efficient gasoline vehicles.)
However, oddly, the government decided to allocate a fixed number of stickers (which makes sense) and to release them on a first-come, first-served basis, which makes no sense. After the allocation is issued, new buyers of these cars, or future efficient cars can’t get the stickers. (Or so they say — in fact the allocation has been increased once.)
The knowledge that time was running out to get a Prius with carpool privileges was much talked about. And it’s clear that a lot of people who buy a hybrid rush to get one of the scarce carpool permits simply because they can, even if they will almost never drive on the highways at rush hour with them.
Society seem to love first-come-first-served as a good definition of “fair” but it seems wrong here. At the very least there should be a yearly fee, so that people who truly don’t need the stickers will not get them “just in case.” I would go further and suggest the annual fee be decided by dutch auction. For those not familiar, in a dutch auction, all those who wish to bid submit a single, sealed bid. If there are “N” items then the Nth highest bid becomes the price that the top N bidders all pay. There may be a minimum below which the items are not sold.
This can be slightly complex in that you can do this one of two ways. The first is everybody pays their real bid, and losers and overbidders get a refund. This assures all bidders are serious. The other is to set the price, and then bill the winners. The problem here is people might bid high but then balk when they see the final price. You need a way of enforcing the payment. Credit cards can help here. As can, of course, being the government, which can refuse to licence your car until you pay the agreed fees.
Carpool lanes are a hot topic here, of course. The mere mention of the subject of kidpooling (Counting children to determine if a car is a carpool) makes the blood boil in the local newspapers. People feel remarkable senses of entitlements, and lose focus of the real goals — to reduce congestion and pollution. Emotions would run high here, too.
Submitted by brad on Sun, 2007-01-07 21:57.
In one of my first blog posts, I wrote about virtual right-of-way, a plan to create dedicated right of way for surface rail and bus transit, but to allow cars to use the RoW as long as they stay behind, and never in front of the transit vehicle.
I proposed one simple solution, that if the driver has to step on the brakes because of a car in the way, a camera photographs the car and plate, and the driver gets a fat ticket in the mail. People would learn you dare not get into the right-of-way if you can see a bus/train in your rearview mirror.
However, one downside stuck with me, which is that people might be so afraid of the ticket that they make unsafe lane changes in a hurry to get out of the way of the bus, and cause accidents. Even a few accidents might dampen enthusiasm for the plan, which is a shame because why leave the RoW vacant so much of the time?
San Francisco is planning BRT (Bus Rapid Transit) which gives buses dedicated lanes and nice “stations” for Geary St., its busiest bus corridor. However, that’s going to cut tremendously into Geary’s car capacity, which will drive traffic onto other streets. Could my plan for V-Row (Virtual Right of Way) help?
My new thought is to make travel in the V-Row a privilege, rather than something any car can do as long as it stays out of the way of the bus. To do that, car owners would need to sign up for V-Row access, and purchase a small receiver to mount in their car. The receiver would signal when a bus is approaching with a nice wide margin, to tell the driver to leave the lane. It would get louder and more annoying the closer the bus got. The ticket would still be processed by a camera on the front of the bus triggered by the brakes.
Non-registered drivers could still enter the V-Row, whether it was technically legal or not. If they got a photo-ticket, it might be greater than the one for registered drivers who have the alerting device.
I’ve thought of a few ways to do the alert. If there are small, short range radio transmitters dotted along the route, the bus could tell them to issue the warning as they approach. They could also flash LEDs (avoiding the need for the special receiver.) Indeed, they could even broadcast on a very low power open FM channel, again obviating the need for a special device if you don’t mind not running your stereo for something else. (The broadcast would be specific, “Bus approaching on Westbound Geary at 4th ave” so you are not confused if you hear a signal from another line or another direction.) Infrared or microwave short-range transmission would also be good. The transmitters would include actual lat/long coordinates of the zones to clear, so cars with their own GPS could get an even more accurate warning.
It might even be possible to have an infrared or ultra-high-frequency radio transmitter on the front of the bus, which would naturally only transmit to people in front of the bus. IR could be blocked by fog, radio could leak to other zones, so there might be bugs to work out there. The receiver could at least know what direction it is going (compass, if not GPS) and know to ignore signals from perpendicular vehicles.
Each bus of course, via GPS will know where it is and where it’s going, giving it the ability to transmit via radio or even IR the warning to clear the V-Row ahead of it.
V-Row is vastly, vastly cheaper than other forms of rapid transit. In fact, my proposal here might even make it funded by the drivers who are eager to make use of the lane. Many would, because going behind the bus will be a wonderful experience compared to rush hour traffic, since the traffic lights are going to be synchronized to the bus in most BRT plans.
One could even imagine, at higher pavement cost, a lane to pass the bus when it stops. Then the cars go even faster, but the driver signals a few seconds before she’s going to pull out and all cars in the lane would stop to wait for it, then follow it. Careful algorithms could plan things properly based on bus spacing and wait times and signals from drivers or sensors to identify where the gaps in the V-Row are that will allow cars are, and to signal cars that they can enter. (The sensor would also, when you’re not in the V-Row, tell you when it’s acceptable to enter it.)
During periods of heavy congestion, however, there may not be anywhere for cars leaving the V-Row to go in the regular lanes without congesting them more. However, it’s not going to be worse there than it is with no cars allowed in the bus right-of-way, at most it gets that bad. It may be the case the bus drivers could command all cars out of the V-Row (even behind the bus) because congestion is too high, or transit vehicles are getting too closely spaced due to the usual variations of transit. (In most cases detecting transit vehicles that are very close would be automatic and cars would be commanded not to enter those zones.)
There are many other applications for a receiver in a car to receive information on where to drive, including automatic direction around congestion, accidents and construction. I can think of many reasons to get one.
Some BRT plans call for the dedicated right-of-way to have very few physical connections with the ordinary streets. This might appear to make V-Row harder, but in fact it might make planning easier. Cars could be allowed in at controlled points, like metering lights, and commanded to leave at controlled points. In that case there would be no tickets, except for cars that pass an exit point they were commanded to leave at. If the system told you to stay in a lane and was wrong, and a bus came up behind you, it would not be your fault, but nor would it be so frequent as to slow the bus system much.
Submitted by brad on Thu, 2006-11-30 20:56.
Parking at airports seems a terrible waste — expensive parking and your car sits doing nothing. I first started thinking about the various Car Share companies (City CarShare, ZipCar, FlexCar — effectively membership based hourly car rentals which include gas/insurance and need no human staff) and why one can’t use them from the airport. Of course, airports are full of rental car companies, which is a competitive problem, and parking space there is at a premium.
Right now the CarShare services tend to require round-trip rentals, but for airports the right idea would be one-way rentals — one member drives the car to the airport, and ideally very shortly another member drives the car out of the airport. In an ideal situation, coordinated by cell phone, the 2nd member is waiting at the curb, and you would just hand off the car once it confirms their membership for you. (Members use a code or carry a key fob.) Since you would know in advance before you entered the airport whether somebody is ready, you would know whether to go to short term parking or the curb — or a planned long-term parking lot with a bit more advance notice so you allocate the extra time for that.
Of course the 2nd member might not want to go to the location you got the car from, which creates the one-way rental problem that carshares seem to need to avoid. Perhaps better balancing algorithms could work, or at worst case, the car might have to wait until somebody from your local depot wants to go there. That’s wasteful, though. However, I think this could be made to work as long as the member base is big enough that some member is going in and out of the airport.
I started thinking about something grander though, namely being willing to rent your own private car out to bonded members of a true car sharing service. This is tougher to do but easier to make efficient. The hard part is bonding reliability on the part of all concerned.
Read on for more thinking on it… read more »
Submitted by brad on Tue, 2006-11-14 16:10.
It does get hard to be a privacy advocate when it’s easy to think of interesting apps that make use of tracking infrastructure. Here’s one.
How often have you wanted to talk to somebody in a car next to you on the road? Consider a system where people could register their licence plate(s) with their cell phone account. Then, if they had done this, you could call a special number on your own cell phone, and enter the numeric part of their licence plate.
If both you, and the other car were close by (for example in the same cell, but often the cell companies have much closer tracking information) and both of you were moving, it could then complete the call to the other car. The other car might get to screen the call (ie. you would have to enter the reason for the call and they would hear, “Will you accept a call from about .”)
Sounds like a good product for the cell companies, able to generate minutes. Easy enough to do if both people use the same cell company, lots more work between two different companies where a protocol would be needed. Would be easier to do with texting but you don’t want people texting in cars.
Could have used it last night, was tailing a friend on the road to her house, did not have her cell number but could see her plate.
As I’ve described the system it’s opt-in, nobody calls you unless you sign up for it and register a plate. However it could be made fairly safe to opt-in with a number of protections. As noted, the system could demand the cars are moving (cell network can see that) so that it can’t be used to reach your cell phone while you are not driving. You could have screening.
It should also have a reputation system. For example, if you call me, then after we disconnect I can leave a negative reputation comment on you. Get a few of these and you’re out of the system. This assures people don’t use it simply to express road rage at the next driver or other things that are largely annoying. On the other hand you can use it to tell people their blinker is blinking or their trunk is open. (Mind you, once you are aware of a problem you would want a function to tell callers you are aware of a driving problem and to press 2 if they are calling about something else.)
And sure, for those open to it, it would be used for flirting with the cutie who gave you the eye when you were both stopped at the light.
You can of course just stick your cell number on your bumper to do this, but it would not have the opt-out and reptuation systems. With today’s cheap phone numbers, however, you could get a special number that forwards to your cell and performs the screening/reputation/etc. but is not able to use the location awareness.
If the digits are not unambiguous (or, like me, you have a custom plate that’s all letters) the system would need to offer you the cars close to you that match.