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Traffic Light Control For The Masses
uniformed1 writes "Eliminating red lights along the routes of their vehicles can give
emergency response teams the few extra critical minutes that can save
lives and property. A front page article
in today's Detroit News details
the emerging problem with a device that is now being made available to
the public -- a traffic light changer. Originally intended only
for emergency vehicles, the $300 MIRT (mobile infrared transmitter)
emits an infrared beam that signals traffic signals to turn green and
gives the vehicle the right-of-way. It is only a matter of time
before self-centered drivers start using the devices widely to skirt
traffic congestion, which is creating fears that chaos will
ensue." Maybe if everyone had these, it would lead to smarter intersections.
One thing to do, then, would be to change the behavior of the traffic lights so that on receiving this signal, they go to four-way red. Since emergency vehicles can run red lights, it doesn't stop them, while simultaneously deterring civilians from using them.
(The trouble is the lack of feedback. You'd need some kind of indication that the other ways had gone to red before the ambulance driver will have confidence going through the intersection at full speed)
The specs have been out on how to build these things for years. Never caught on, maybe because they felt like the whole beige/black/red/blue box phenomenon. MAYBE if they start showing up in places like Best Buy it will catch on, but even still, I doubt it. Besides, I asked some EMTs/the driver one time if the light at the intersections would benefit them by this light predetermination technology. They said no. Doesn't matter because people still run the yellow and red lights so they still have to slow down. And this was for a signal 100 ft. from the station driveway.
I concede that yes, it may help in congested downtown areas like LA or NY, but in 95% of the U.S. they either aren't installed or useful enough to justify their cost.
BTW, it's just a pre-canned, encoded signal on a fixed carrier wave over an infrared signal. Think "really powerful remote control" for you newbies.
There are sensors on the top of traffic lights in the UK that respond to headlights.
If an ambulance is approaching lights on red he can flash his full beams a few times and the sequence changes.
I use this feature all the time at the lights near my house, especially late at night when the deafult sequence on the lights is to stay green for the main road all the time unless a car approaches on the minor road.
"Maybe if everyone had these, it would lead to smarter intersections."
Maybe if everybody drove the speed limit they'd synchronize with the timers in the traffic lights and not get stopped by a red light to begin with.
(It also provides the enjoyment of sailing past the Honda weed-eaters, the ones that just had to hurry up and beat everybody else to the next red light.)
Although I lived almost three years in Northern California and disliked the place as a whole, the one thing that did stand out is the outstanding traffic control system with optical and pavement vehicle sensors. The volume of traffic notwithstanding, it was the fairest traffic systems I've ever seen.
For example, if there are left turn lanes on opposing lanes at an intersection, and one of those lanes is empty but the other is full, when the lights turn green the left turn lane for the empty lane stays red and simultaneously turn the signal green for opposing straight-through traffic. Not only that, but the left turn signal would only stay green until the last car had cleared or until a maximum time interval elapsed, at which point it would turn red again and allow opposing straight-through traffic to flow. In fact, if there was no waiting straight-through traffic in the one direction, some lights would just stay green for the lanes that had it until a car attempting to cross the intersection would trigger a timer.
Contrast this with, say, Edmonton, Alberta's dreadful traffic system, where nearly everything is on straight timers save for buses with road sensors and emergency vehicles, and there are no timing lights for freeway on-ramps. There are some sensors at some intersections, but by and large nearly everything is timed and it creates frustration and accidents. It's doubly ironic considering that Edmonton has the highest density of traffic lights in North America and traffic circles on major roadways!
In other words, if you design your traffic system the right way the first time, devices like this become unnecessary. An economist once commented that traffic lights are a nearly perfect unbiased system for resolving conflict. Why create bias in favor of certain selfish individuals? It doesn't work in economies, and it doesn't work on roadways.
Here are some of the vehicle traffic laws as they pertain to emergency vehicles here in New York State, other states are mostly similar.
Only police department vehicles are allowed to proceed through red lights without stoping.
EMS and Fire trucks have to make a full stop at every red light while going lights and sirens to a job, regardless of the priority.
In reality, I slow down significantly and roll through at a cool 3-5mph.
Lights and sirens for EMS and fire are a courtsesy. The guy in front of you is in now way obligated to blow a red light for you if he feels it's unsafe for him to proceed. Oh, and btw, if a medic or emt gets on the P.A. and tells you to cross a red light, and you get into and accident, the medic is at fault for the acccident.
Going down one way streets and driving on the opposite side of the road are allowed, with the understanding that you do so at reduced speed and with extreme caution, any accident in this situation is all on your shoulders.
Here in Manhattan, slow and steady is the best way. You can't justify injuring bystanders for someone who is already sick.
And with critical patients in the back, you'll drive even slower to the hospital 'cause there's alot of things that we need to that can't be done if you're bouncing around the back cab like a virgin's first visit to some Panamanian wha wha rumphouse.
These device have been mentioned here in the city, and it was agreed that it would cuase more confusion and possibly more liability for the city than it's worth.
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First, it didn't always work. Those sensors are positioned to see the pulsing signal from a light on top of a tall vehicle, like an ambulance or fire truck. He had an ordinary car which meant it was a lot lower than it should be. The sensors seem to have a cone-shaped sensitive area which obviously narrows you approach the intersection. So as he got closer to the intersection, where the weaker light might have a chance, he'd usually be outside the sensitive cone shape.
Second, it was hard to tell when it was working. We did get what seemed like an unusually large number of green lights... but it was hard to tell if the "go box" was triggering them, or if we were just getting lucky. In several cases, traffic was also flowing through the intersection the other way which meant it hadn't done anything. Apparantly, the lights turn red in all other directions.
However, we did approach one intersection where there was absolutely no doubt it worked. The light was green, turned yellow, and then turned green again. That absolutely never happens under normal circumstances, and when I saw that I knew it did indeed do something. This interection was approaching the crest of a small hill, and it was complex with five streets (one at a funny angle). As we got closer, the light must have bounced off something else, because the obviously unnatural green light we got turned yellow briefly and then red. I don't know what the drivers saw in the other four directions approaching the interestion, but they must have seen something equally strange, because we sat there for a LONG time as did the cars in coming from the other directions. NOBODY was willing to drive into that interestion, because it was obvious to all the cars that the light was screwed up somehow. That's something that virtually never happens. Traffic lights are incredibly reliable (must not be running Microsoft's products). And when confronted with a screwed up light, nobody was willing to be the first to risk driving into the intersection, even as the controller recovered and started it normal sequence giving green lights. After about 10 minutes, people started to believe a green really was safe and we got to move forward. This was during rush hour on a very busy 4-lane road... so it must have caused quite a bit of traffic backup.
Anyway, my friend's "go box" (as he called it) eventually stopped working. It was home made and it used massive power to turn on those LEDs. They were probably running many times over their rated current. He couldn't turn the switch on too long or it'd blow the fuse to his cigarette lighter. Apparantly he'd replaced the normal fuse with 30 amps which allowed it to run for a minute or so. The wires and everything else about it got really hot. So it's no wonder it stopped working after a while. He talked a few times about building a bigger and better one... but ultimately it was not worth the effort. It couldn't reliably trigger most of the lights. He had many other stories of turning a light green and being stuck behind someone who'd just stopped and wasn't paying attention to the light because it wasn't expected to turn green again for a while. He used to joke "you really also need the lights and siren to make the other cars get out of your way".
Posting anonymously for obvious reasons...
OK, a few things here (and yes I have experience wiht this, only not with an ambulance, but with a fire truck, however the concepts are still the same.)
First off if the ambulance driver is any good, he/she does not go full speed through a green light, or a red light, or a yellow light for that matter. If they are really good, they stop and make sure they have the right of way. Believe it or not, in most cases that have made it to court where an accident occured between a civilian and a emergency vehicle, the Emergency Vehicle driver was held accountable. This is true even in the case where the Ambulance had a green light to go and the ambulance was struck BY the civilian running a red light. (I don't remember the specific case but was taught to us when we took our driving course.) Personally I stop at every light, green or not and make sure that I have EVERYONES attention before going through an intersection. It is better to get my truck, and my fellow fire fighters there in one piece than to crash the truck and not get there at all.
Another interesting point of fact, (at least in New York state) the flashing red lights give NO legal rights to disobey the speed limit. This is something I allways try and keep in mind, because you do kind of feel invincible when you are driving those big red trucks.
Of all the things I miss
Well, police departments, or rather their vendors, already face these issues for encrypted radios. Typically a fixed key is used for a large group of radios for a period of time, loaded via a key loader box. Some systems allow OTAR - over the air rekey, where the new key is encrypted with (I think) the old key and broadcast.
This problem is a little harder because an attacker could steal either the traffic light equipment or the vehicle equipment. The traffic light equipment is probably more numerous and vulnerable. Public Key crypto would be very useful here, because then stealing the receiver doesn't help you impersonate the transmitter. Unfortunately, it probably needs too many bits for the IR strobe carrier. So unless we "cheat" with a supplemental data channel or something, there's no good solution.
Although - you could have an operational key (symmetric) and a rekey key (public key). The rekey box is guarded like the crown jewels. Once a month, or if the operational key is known to be compromised, you bolt the rekey box to the roof of a police car and drive slowly around town, pausing 60 seconds or so at each light. Enough time for the slow public-key transmission. Then you rekey all the vehicle units off the rekey box. Could work.
Why not have a system where you pay as much as you like to whoever fixes/controls/maintains your local roads. You would have a box on your car that wirelessly beamed your ID number to traffic lights as you came up to them. If you were the only person at the intersection with a box, you would 'win'. If there were two people, then the one with the highest balance would win, if there were three, it would be the combined balances of the two going in one direction etc. And whatever money you donated would be reduced by 1/365 each day.
All the money gathered would be put back into road maintenance/improvement.