dedicated turning lane policy

[kianzarrin]

there should be an option that all jun intersections would have dedicated turning lanes by default.

edge cases:

• bus lanes
• 2 lane roads with 3 directions to go

related: #716

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basically what this mod does: https://steamcommunity.com/sharedfiles/filedetails/?id=2119310640
I don't know why is this not in TMPE.

UPDATE:
I handled the bus lanes like #1102 (comment) which is different than the Improved turning lanes mod. the bus lanes still have forward+right but the non-bus lanes have dedicated turning lanes where possible.

[kianzarrin]

Bus Lanes

Bus lanes normally work work good .

But if even in vanilla mode the bus lanes can only turn right (not forward). then the results are less than ideal.

Before

###After:

This is because I don't touch bus lanes if there is only one lane. But now I understand that I should. I might need to write some dedicated code for buses rather than using the old code.

But if I do that then I cannot call it dedicated turning lanes any more but rather improved turning lanes.
Or maybe I should just copy paste the code from the existing mod.

[kianzarrin]

delta-5 The way bus lanes are implemented in the game is that cars are allowed to use them, but prefer not to, unless they need to. There are two reasons why cars may need to use a bus lane: (1) on the next junction they want to go in a direction that is only reachable from the bus lane (as dictated by lane arrows/connections) or (2) to access a roadside building. The mod eliminates the 1st reason for them to use bus lanes, as it always provides them with the option to turn into whatever lane they need to from "normal" car lanes. That alone is enough to eliminate most cars from bus lanes.

With regards to what delta-5 said and #1102 (comment) can I have some 2nd opinions on this matter?

[kianzarrin]

I think All I have to do is to add forward arrow (where applicable) to the bus lanes and we will be fine

[kianzarrin]

how is this?

(some bus arrow props are not visible because I didn't find a good network ... but they are consistent with the rest of the picture)

[kianzarrin]

The first column shows in which direction vehicles can turn at the segment end.
- eg:  LFR means Left+Forward+Right as in a "+" intersection
- eg2: LR means Left+Right as in a "T" intersection.

The other columns show lane configuration
- eg: CAR BUS means two-lane road with a bus lane.

TMPE lanes.txt

[kianzarrin]

just for feature sake to separate car lanes from bus lanes when there is enough lanes you can do this:

                if (busLanes.Count > 0) {
                    // this optional piece of code imrpoves the lane arrows a little bit in some edge cases.
                    // see https://github.com/CitiesSkylinesMods/TMPE/pull/1104#issuecomment-834145850
                    int numLanes = GetCarLanes(segmentId, nodeId).Count;
                    int numDirs = CountDirections(segmentId, nodeId);
                    if (numLanes >= numDirs) {
                        // if there are enough lanes, try to have dedicated bus lanes.
                        SeparateSegmentLanes(
                            segmentId,
                            nodeId,
                            out res,
                            NetInfo.LaneType.Vehicle,
                            LaneArrowManager.VEHICLE_TYPES,
                            builtIn: builtIn,
                            alt2: alt2,
                            alt3: alt3);
                    }
                }