Right turn on red

[Bub]

In the United States, certain intersections allow right turn on red. Some states usually allow this, while others typically don't. This would allow right turning vehicles a quick right on red, while left turning vehicles and thru vehicles must stop at the light. Thus another topic begun by me at http://forum.simutrans.com/index.php?topic=10392.0

^{Mod note: Link fixed.}

[Ters]

That would cause the vehicles to get in the way of traffic from the left.

[Bub]

You did'nt read my topic at the link, Ters.

[Ters]

Yes I did, even though the link doesn't work. But do you know how vehicles in Simutrans move?

If there is a traffic light in Simutrans, it's usually because there is almost constant traffic in that intersection. A vehicle driving past red to turn right would have a very high chance of forcing a vehicle coming from it's initial left to stop, despite the fact that it had a green light. If the first vehicle yields, then the ability to turn right on red is unused and useless.

[ӔO]

IMO, it is better to just stop all traffic at a red light.

Allowing turning to nearest shoulder lane on red conflicts with advanced green cross over traffic. Plenty of bad drivers think they are allowed to turn on red when the oncoming has an advanced green and it results in many near misses.

Besides that, simutrans doesn't support advanced green lights anyways.

[isidoro]

Technically, if I recall it correctly, it is not simple.  There is also some logic programmed in crossroads to try to avoid deadlocks and jams, for instance.

Besides, that is not a general behavior in all countries.

[IgorEliezer]

I rather prefer to keep Simtutrans as simple as possible. If one way is closed, the other is free.

When the one-way-multilane feature is done, we could think of new kinds of traffic signals for intersections that could give different "behavior" for each lane of each direction of each way.

A detail: city cars are decorative and lots of memory is already spent on them to check the data of the tile ahead. More complicated data for intersections would demand more resources for a decorative element, I presume.

[Ters]

A detail: city cars are decorative and lots of memory is already spent on them to check the data of the tile ahead. More complicated data for intersections would demand more resources for a decorative element, I presume.

I think that's the main thing, but not just city cars. Even if we had the capacity to make a better AI for road vehicles, it could easily have a too huge impact on performance to be practical.

[Bub]

Right turn on red is only permitted if the way is clear and at only certain intersections

[Ters]

Right turn on red is only permitted if the way is clear

Which is the catch. Vehicles in Simutrans have a very limited ability to see whether the way is clear. Traffic lights is a way to help them with this, but it only works as long as the vehicles strictly obey them. And even then, left turns still cause conflicts.

Though developers are aware of possible solutions based on real world solutions, Simutrans is currently too simplified for real world solutions to fit easily. One would either have to increase the realism in Simutrans, which takes time, requires more processing power and memory for running the game, and might make the game less fun for some; or one needs to think out of the box, which also takes time.