OT traffic lights

[Tim W]

dennis@home wibbled on Wednesday 21 October 2009 10:47

Unless you're on blues & twos in which case you may process with caution over steady red, but *never* over flashing red.

[Adrian]

Matty F gurgled happily, sounding much like they were saying:

I've never seen a set of traffic lights with a red period anywhere _close_ to that.

[nightjar]

While cameras may reduce the number who jump the lights, unlike the delay, they do nothing to reduce the risk of a collision when someone does jump the lights..

Colin Bignell

[Roger R]

The waiting time for the lights to change that you describe is the period between green ending one way and green appearing the other is known as the intergreen period.

The length of the intergreen is determined by the particular circumstances. Probabably the junction you mention has a high record of red light runners or some other factor.

Have a look at these four papers which provide a useful introduction and explanations of the intergreen and other periods in the cycle (second paper in list):

above papers are all on this page: computer control programmes have been developed for more complex situations such as linking several sets of lights on the same road or for co-ordinating control of lights in urban areas to prevent gridlock.

Explore the other papers here:

page on American traffic lights is fairly interesting: R

[Andy Champ]

... and of course as soon as the junction gets known for having this long gap, more people start running the lights...

Andy

[Matty F]

I'm not talking about the intergreen period. I'm talking about the period from when the bus arrives at a red light until the green light on an empty cross road changes to orange. I maintain that that period should be zero seconds. Nobody has come up with a good reason for that period to be. say, 10 seconds or more.

[The Natural Philosopher]

Then yiou haven't looked.

Typically it avoids the need for a hugely dangerous pedestrian crossing with lights 5 yards down the road. Which means yiou see those ligjhts go green..when yours are red.

Anyway, its all bollocks. Every time they put in a set of lights anywhere, congestion gets worse.

[The Natural Philosopher]

'Ive got a pain in my diodes, all down the left hand side'...

[Matty F]

It is necessary to keep to a precise published schedule, e.g. exactly every 10 minutes or 12 minutes or 15 minutes. Times such as 11:00,

11:12, 11:24, 11:36 etc are published. No divisors other than 4, 5 or 6 divide evenly into 60 and give a result between 12 and 15. The trip cannot be done in 10 minutes without speeding. If the trip takes 15 minutes then not enough passengers can be carried per hour to keep up the demand, so another vehicle (or larger) will be needed at great expense. Therefore the trip must be done in 12 minutes at most. I used the term "bus" rather loosely!

The vehicle does not have a simple, ordinary accelerator:

are even more complications, involving the difficulty of the vehicles passing each other. That may be done only at certain places, at certain precise times!

[Arfa Daily]

Wasn't it all the diodes in his left leg ... ? d;~)

Arfa

[JTM]

[snip

I guess you didn't look at the jpeg. Ah. timed at 02:29 that might explain it :-)

[Matty F]

There are basically no stops except at each end of the run. So, nobody to wait for.

There are no dustcarts because there are no houses for the entire run.

The "vehicles" have their own road that nobody else is allowed on, not even pedestrians. The only possible delay is at the traffic lights, where there is an unecessary 10 to 20 second delay. Every little time saving helps.

[dennis]

Not legally. They can only exceed the speed limits legally.

[Tim W]

dennis@home wibbled on Friday 23 October 2009 19:28

But they do - and they will not be prosecuted for it unless they cause an accident.

However, they *will* be prosecuted if caught going through a set of flashing reds at a level crossing (or anywhere else flashing reds are used).