One major flaw of designing societies around cars is the sheer amount of signage that drivers are expected to recognize, read, and react to. It’s a highly complex system that requires constant vigilance to a relatively boring task with high stakes, which is not something humans are particularly well adapted for. Modern GPS equipment can solve a few of these attention problems, with some able to at least show the current speed limit and perhaps an ongoing information feed of the current driving conditions., Trains, on the other hand, solved a lot of these problems long ago. [Philo] and [Tris], two train aficionados, were recently able to get an old speed indicator from a train and get it working in a similar way in their own car.
The speed indicator itself came from a train on the Red Line of the T, Boston’s subway system run by the Massachusetts Bay Transportation Authority (MBTA). Trains have a few unique ways of making sure they go the correct speed for whatever track they’re on as well as avoid colliding with other trains, and this speed indicator is part of that system. [Philo] and [Tris] found out through some reverse engineering that most of the parts were off-the-shelf components, and were able to repair a few things as well as eventually power everything up. With the help of an Arduino, an I/O expander, and some transistors to handle the 28V requirement for the speed indicator, the pair set off in their car to do some real-world testing.
This did take a few tries to get right, as there were some issues with the power supply as well as some bugs to work out in order to interface with the vehicle’s OBD-II port. They also tried to use GPS for approximating speed as well, and after a few runs around Boston they were successful in getting this speed indicator working as a speedometer for their car. It’s an impressive bit of reverse engineering as well as interfacing newer technology with old. For some other bits of train technology reproduced in the modern world you might also want to look at this recreation of a train whistle.
I always thought that obsessively trying to stay dead-on the exact posted speed limit and looking over your fiddly indicators and dials was detrimental to safety. Keep a general speed around the posted limit and your eyes on the road, you can tell what speed you’re going close enough for safety’s sake. Maybe an audible signal if you go over if you want to feel like an Amazon delivery driver with a robot cop breathing down your neck
In the 1970s when the US went to a 55mph speed limit (to save fuel), you could get a speedometer add-on that would buzz if the speedometer needle crossed a certain point. Very old-school.
Nowadays the EU mandates that all new cars should hoot and ring bells at you for exceeding the (mis-identified) local speed limit. You can turn it off, but it has to default back every time you start the car.
It’s even worse in EVs when there are no audio cues. In a petrol car you can internalise what 2000rpm sounds like and you know you’re in third gear so this is likely 30mph or thereabouts. EVs it’s all speedo until the wind noise picks up.
My old car had a manual speed limiter that reduced motor power as it got closer to the set limit and that was great for set-and-forget driving in cities with 30mph limits. I could keep my eyes on the road and only think about speed when changing to a new limit. My new car only has the mandated automatic bing bongs. I miss manual limiters so much.
How many new cars can you even hear the engine clear enough to discern speed? Partly due to comfort, partly due to federal noise regulations (in the US) cars engines make very little noise unless your accelerating hard.
It may be the combination of motor/transmission noise, tire noise, and wind (as opposed to just engine noise alone) but that composite sound–at least in an ICE vehicle–absolutely contributes to a sense of speed and overall situational awareness.
As to the matter of “regulations,” as a person who lives adjacent (what once was) a dirt road that has since become a four-lane highway, I can confirm being aware of every car that blows past my house, regardless of “federal noise regulations.” I’ll bet money that I could also tell you, with fair accuracy, which ones were speeding and which were not .
It’s the same thing in automatic cars, since the engine speed and road speed aren’t directly linked anyhow.
They are for anything over about 30 MPH and below a certain power level thanks to the TCC – torque converter clutch. It locks the engine to the transmission input shaft to eliminate slip and improve fuel economy. Most automatics have had it or similar since the early 1980’s.
https://x-engineer.org/torque-converter-clutch/
Generally keeping at the speed limit is useful when a road is empty. When other traffic is on the road, the speedometer is nearly irrelevant: the goal is to match speed with the flow of traffic. If you’re drifting forward or backward relative to other vehicles because you’re trying to hit an arbitrary ground speed rather than trying to keep relative speed to a minimum, you are an active hazard to everyone else.
If you drive under the limit, other people start tailgating you. If you get stuck behind some sunday driver doing 90 kph on a 100 kph zone, it’s better to pass.
“Oh, what terrible traffic we had today. The lines stretched for miles, and I couldn’t pass anyone since I was at the head of it.”
This has always been my feeling as well. There are some towns I occasionally drive through that will pull you over for 27 in a 25. All i could think of is that if a kid or someone ran into the road i wouldnt see them because im staring at the speedometer. I use cruise control in this situation to keep my eyes on the road but not all cars allow cruise control to be set that low for unknown reasons.
They are called “speed traps” and exist mainly to line the pockets of town “officials”.
https://reason.com/2022/05/08/11-insanely-corrupt-speed-trap-towns/
https://ww2.motorists.org/issues/speed-traps/
Isn’t cruise control what one uses to keep constant speed (except at very low speeds)?
People don’t have time to adhere to the speed limit or even look at their dash, they’re too busy looking at their phones!
This is what I did on a motorcycle, because it’s quite easy to gain some speed without really noticing if you are just cruising down a long road. I got a phone app that announced my speed every 5 mph change, or once every minute, so could look at the road and stare at my speedo.
This summer I experienced speed warning devices first hand in Europe. The EU requires new cars to have speed warning devices, i.e. if you go over the speed limit the car starts complaining (and in the future possibly even limiting the speed).
Neat idea, but the system definitely didn’t work as intended. Every single time I drove the car (for about a month), it’d get some speed limit wrong. Usually claiming lower limits than were in place in reality, but occasionally the other way, too. The common cases were it claiming it’s 130 instead of 100, and 30 instead of 80. Not to mention what must’ve been GPS based limits in former construction zones where a 120 area was claimed to be 50.
While it could be turned off, the system would reset with the next engine start.
Not ready for prime time, but when did that ever stop regulators and politicians.
And don’t get me started on the “collision avoidance emergency breaking system” that almost caused two accidents and prevented none. Also required by EU regulations.
I live in Prague, Czech Republic – and i see how this is useful – i don’ have this in car but waze has this future and yes i do have it ON – the reason? Bills. Average speed enforcement is very common here and it is very well automated now – you drive more? The camera will read the plate and in couple of weeks automated letter will come into your mail saying that if you pay now, there will be no more repercussions and if you don’t, it will be more expensive and points will be added to you driving account (12 points = you loose your license for 1/2 year, speeding is 2 or 4 points depending on the speed). In other larger cities it is very similar. An we have very low fines compared to countries like Switzerland – try speeding there – or maybe not.
I’m trying to wrap my head around this. There is some huge database that looks how often your license plate is seen out and about, then mails you an extortion letter for a sum of money, saying if you don’t pay it will fine the crap out of you and potentially take your license?
Craig, that system is old enough to have had the “points” to be literal points on paper.
Don’t worry about the auto-braking systems in the US. They will be MUCH better, because the law requiring them says they have to work correctly.
I think we have passed peak safety for at least a few years, and until some significant technological progress is made, things will get worse rather than better as new concepts come on line.
I’m in the US, and just bought a new car last year. It has the ability to recognize speed limit signs via exterior cameras, and it will display said limit on the dashboard and HUD while I’m driving.
I’ve noticed the same issue you mentioned – occasionally, an obscured / dirty/ damaged speed limit sign will cause the car to display some wildly wrong speed limit – I’ve seen my car read a 30mph (48 km/h) speed limit sign on a local road as 80mph (129 km/h) and 15mph (24 km/h) on a 65mph (104 km/h) interstate highway, for instance.
https://www.nytimes.com/2024/03/11/technology/carmakers-driver-tracking-insurance.html – apparently some of the car manufacturers were sharing this data, too. That didn’t go over well with consumers.
Perfect application for the mythical 555 timer! Make a one-shot to push the button to turn the statist nanny off after the car is started.
(Did that once years ago for a truck with tow/haul mode that turned off every time it was started. Very annoying when stopping frequently while pulling a trailer.)
As a railway Signalling design Engineer, I love this.
Would be cool if formal standardised systems like this were installed on the roads.
Maybe with automatic stopping if speed is exceeded?
Like PZB90 in Germany? You have to press an acknowledge button for pretty much every speed limit or warning sign, and get the emergency brake applied if you do it too late, or if you don’t go below a certain speed afterwards — sounds fun for road traffic :-D
(de.wikipedia.org/wiki/PZB90 german version, the english version has less detail)
Hah. Somehow don’t think ATP Level 2 type systems would be popular with a lot of road users :p
Every portable navigator I’ve seen shows the speed limit on whatever street etc. I am on. Seems like that’s the easy way, however update and emergency changes are absent for sure. There needs to be a public service way of doing the later, either cell band service or dedicated VHF service everywhere that interfaces with all “maps”.
California is going to have speed warnings too and the rest of the US will have to follow. I have one loaded question: will self driving cars break the law and go with the flow or will they set the pace to enforce that flow? There is a law in the US that says you must leave the passing lane driving at the speed limit if someone wants to pass, non emergency just because they are late and in a hurry and want to break the orderly flow on the interstate. Dumb, and this will not pass (pun) when we can have some enforced unity in speed.
A much cooler alternative (I believe) would be to use a HUD as it displays your speed and the speed limit along with many warnings as if they are on the road.
After reading most of the first paragraph I started thinking… we are going to get gamification of driving apps.
You stopped for a stop sign! 10pts. You have now reached level 3. Share with friends?
And if that takes off.. I’m getting a horse.
I’m more concerned about the opposite.
“You swerved into the other lane.” (To avoid a person who ran into the street)
“Minus 2 points from your driver’s license and a 10% increase to your auto insurance. “
That would certainly help with young new drivers! A precision driving game.
“ding You missed that tree, you can keep your life”
“ding You mastered that cuve, you can keep your car”