Here's how it would work:
A stop sign would be bi-directional, not four-way.
A convoi reaching a stop sign would come to a stop.
No matter which way the convoi turns, Simutrans would look in at least one direction to see if the road was clear for X tiles (configurable by player?). Note that checking-for-clear would terminate at any intersection - if a player wishes to control traffic for close roads, use traffic lights.
If a convoi turns in the direction that would not require it to cross a lane of traffic (i.e. for right-hand drive, a right-turn), only the left tiles would need to be checked. Otherwise, if it was turning across or going straight, both directions would have to be checked (both of the directions not required to stop).
Benefit: Traffic coming from the directions required to stop would cause less slowdown for traffic crossing not forced to stop.
NOTE: For a four-way intersection, placing should toggle between the two ways. For a three-way intersection, one "stop" and two "go" should go around - it might be that the "main" road makes a turn, and a "side" road goes straight... So there would be three possible configurations...
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Yield sign: Same as above, but convois are not forced to come to a stop - if they must stop while the calculation happens, that's okay - but if the way is clear, should resume at full (or perhaps half) speed).
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Four-way stop: Simply causes all vehicles to come to a full stop. If the tile is clear, immediately allowed to accelerate into the intersection.
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I think this would allow more realism in Simutrans. :) (I like using traffic lights, but only at 'major' intersections)
I had similar thoughts that I wanted to post up, but you beat me to it.
I was particularly thinking of the the 'clear tile by x' or 'do not block intersection' as something necessary.
Right now if you set up 3 or 4 road routes that intersect with each other and there are enough convoys, there can be a situation where these routes will encounter a complete gridlock, because the convoys in each line are blocking the intersection where the other convoy crosses over.
forcing the convoys to not stuff up intersections is a must have, especially for hubs with many road connections.
I like this idea, as i do with everything which adds realism and... the possibility of interesting setups :)
:support:
Having everything stop at the intersection doesn't improve the flow. side-/main- street stop signs are a great idea.