My car's cruise control doesn't work unless I am driving at least 25 mph. It's a Toyota Prius. I wish that the lower limit for cruising was more like 10 mph or even 5 mph.
Are there legal reasons for this? If so, are these reasons for safety or otherwise?
The reason that I ask is because I believe that it would be a great feature in a car - to be able to set the cruise control to something as low as 5 mph - for when you're stuck in traffic. If you really know that the traffic is moving at around that average speed (take the total distance of the jam - and divide by the time) cruise control set at that speed would save us all a bit more gas and make our brakes last longer.
Also, studies of traffic flow show that the overall impact of any given traffic jam is actually increased by the mere presence of the few who do the jackrabbit technique (gas it! - whoa! brakes! ... few seconds :: repeat) (I know this from my studies pursuing my Civil Engineering degree).
So, how low does your cruise control let you cruise?
Well cruise control is meant for travelling on reasonably open highways, where everyone on the highway is moving at the same high speed and you don't want to worry about your speed. It is designed for situations where using it wouldn't be likely to result in a crash. Whereas in a traffic jam, the traffic isn't moving freely enough to be able to set cruise control - one momentary lapse in concentration and you would hit the car in front. So I would say it would be a bad idea to have low-speed cruise control for jams. A better idea would be a technology that can sense the distance to the car in front and adjust your speed so as to always be a safe distance from it.
Based on the first response, I would have to assume that the reason for a minimum cruise speed is safety. I don't know about you, but you'd have to be seriously retarded to not know when to override cruise and use your brakes to avoid hitting the car in front of you.
| Quote: |
| Whereas in a traffic jam, the traffic isn't moving freely enough to be able to set cruise control - one momentary lapse in concentration and you would hit the car in front. |
- I have to completely disagree with your point here. The same potential exists if you are not using cruise.
More benefits for this would be:
- fewer drivers would feel the need to change lanes which would greatly reduce overall jam duration
- each car would not have to work as hard as the start/stop...wait... :: repeat
- considerable fuel savings
- increased safety - not increased accidents... remember fewer people would be changing lanes. Also, if everybody is moving at about the same speed, accidents could hardly ever be lethal in my scenario.
I stand by my idea - as a safer, not more dangerous idea --- it really wouldn't take much to have the calculated speed of the jam sent to each car via radio or other signal. Picture the scene from Star Wars III - where all of those flying cars are moving in straight lines -- all apparently going the same EXACT speed. If not an infrastructure improvement, each car could be equipped with a system that looks ahead for movement, and it could possibly even transmit to the cars that follow.[/list] I think the ability of the cruise control to hold low speeds is simply a mehcanical restriction. I'm not sure how they work, but I think that they are not capable of holding very low speeds accurately.
My jeep can hold a speed of about 35, your prius 25, my granparents' grand marquis can hold speeds as low as 15.
I don't think that this would be very useful in traffic jams, because all the cars would have to hold the same speed, and you'll never have a situation where all the cars have the same system. Anyway, if all the cars would cooperate and work together, there probably would not be any traffic jam in many situations.
Where holding low speeds is very benificial, however, is in places with low speed limits, or on rough roads.
In my jeep, for example (which you'll recall can hold speeds only over 35mph), I cannot use the cruise control on roads where the speed limit is 30mph or less, nor can I use it on roads on which 35mph would send the truck airborne.
I think in my case it's also around 25 mph. But cruise control isn't meant for traffic jams. The speed is almost never constant. It changes quite often, from a dead stop to maybe 20 mph. If the traffic is constantly moving at the same rate, but at a really low speed, it may be useful...but I still find it unsafe.
Now, one thing that may be useful in traffic jams and such is dynamic cruise control. The way it works is that the car is able to determine the distance from the front end of your bumper to the car in front of you. It is then able to change the speed depending on the car in front of you. You can set a limit to what the maximum speed can be. I don't have any actual experience with dynamic cruise control, but it's starting to appear as an option in many cars now.
My car is set at 25 mph as well. 2002 Grand Am. I don't think that having the ability to set it at 5 mph in a traffic jam would work very well though. You would still have to break often because most of the time the traffic is at a stand still.
