Dedicated turning vs. dual carriageways

[originalfoo]

@kianzarrin Currently the dedicated turning lanes does this (which is what it's designed to do):

However, in the case of dual carriageways (DCs), normally there wouldn't be dedicated turning lanes on the major road unless it's asymmetric.

Example of a Spanish DC (image from wikipedia):

The outer lanes are generally used by slower vehicles (lorries/trucks) and they expect to be able to drive the whole route without needing to enter the inner lanes (except for occasional overtaking).

Example of a DC in Brazil (image from wikipedia):

In-game, the dedicated turning lanes on the DC are causing strange traffic weaving behaviour at junctions. Normally traffic would stay in lane, but because one lane is being "terminated" (due to dedicated turning lane) traffic is having to weave in to the outer/inner (as applicable) lane as it crosses the junction then back in to its original lane after the junction.

Example of a DC in UK - note the far-side turning lane available due to asymmetry:

The issue is also exacerbated when the junction is on a "kink" in the DC (image below); it's particularly obvious when in first person cam driving down such roads as the vehicles make startling moves when encountering such junctions.

Ideally there shouldn't be dedicaed turning lanes on the DC (a 2+2 lane road in general, not just those with medians) except in following cases:

1. Asymmetric road (the extra lane can be used as dedicated turning lane)
2. 3+ lanes per direction (as this allows slow trucks to use middle lane to bypass any traffic waiting in outer turning lane)

Would it be possible to get an option (eg. "Avoid turning lanes in 2+2 medium roads") to facilitate this? Otherwise the dedicated turning lane feature is making dual carraige ways cumbersome to work with b/c I now have to adjust the lane arrows all the way down those - usually very long - roads.

The result would look like this:

Note also that I can't use Alt+Click or Ctrl+Click shortcuts in Lane Arrows tool to toggle turning lanes (is that a bug btw?); even if I could, it would still be PITA to have to constantly be doing that when working with DC roads.

I know we're in code freeze, but hopefully this wouldn't be too painful to implement because it's just checking for 2+2 lanes before applying turning lanes; pseudocode: if numForward = 2 and numBackward = 2 then ignore.

[kianzarrin]

what about the the far turn in the image above? should that be dedicated?

[kianzarrin]

in this pic there is a median.

TMPE does this to high priority roads.

[originalfoo]

I thought the improved lane arrows mod does essentially same as what our dedicated turning lanes option does?

[kianzarrin]

dedicated turning lane is just that. Its different than improving lane arrows.
if a city is gridlock this might be a quick fix. but might not be the best fix.
To improve lane arrows we need another policy.

[originalfoo]

Something like this?

(o) Dedicated turning lanes // the existing option
    (o) Avoid turning lanes on 2+2 roads

[kianzarrin]

Something like this:
(o) Dedicated turning lanes // the existing option
(o) Improved turning lanes // steal code from existing mod

[kianzarrin]

but only one of them should be selected. so maybe something like this:

• improve lane arrows
  • Dedicated turning lanes
  • Distributed turning lanes

[originalfoo]

Stem user just posted this:

Which makes me think maybe the option should be something like:

On suitable roads, add dedicated turning lanes for:
    (o) Far-side turns (inner-lane; cutting across oncoming traffic)
    (o) Near-side turns (outer-lane; similar to a highway exit)
    (o) Only add near-side turning lanes if there are 3+ lanes

The Limit... option would not apply to 2+ lane roads where there is no "straight ahead" route.

[originalfoo]

It would only leave one lane going on to a two-lane segment.

Yup, lane math needs considering when doing turning lanes. I don't think we've thought of it from that angle before.

Side note: The other issue with 2+2 to 3+2 is the lack of networks that create a smooth connection between the two ...

Yup, I spend ages with Node Controller Renewal and IMT tweaking such junctions.

[bailsafe]

I think it would be beneficial to have the options list as you proposed:

On suitable roads, add dedicated turning lanes for:
    ○ Far-side turns (crosses opposing traffic)
    ○ Near-side turns (nearest to outer lane)
        ○ Only if road is 3+ lanes in one direction

It would help to define "suitable roads", though. Will it include both single and dual carriageways? Will it make exceptions for bus lanes?

[originalfoo]

It would help to define "suitable roads", though. Will it include both single and dual carriageways? Will it make exceptions for bus lanes?

Yeah, there's only so much info we can covey via the options screen. There are loads of edge cases (bus lanes are treated as dedicated right of way for buses so aren't counted as road traffic lanes IIRC - if user needed extra lane as turning lane, they'd have to replace segment at junction with one that doesn't have bus lanes to allow other traffic to use it).

IMO we could probably do with an Only if road is 3+ lanes sub-option for the far-side turns too? In many cases IRL (at least in Europe) 2+2 roads don't get dedicated turning lanes - they'd usually add a 3+2 "segment" near traffic lights to facilitate dedicated lane for far-side turns.

[kianzarrin]

There is a difference between dedicated turning lane and improved lane arrows. There is a mod that does the latter. Maybe we should integrate it inside TMPE?

[kianzarrin]

If somebody asked for improved turning lane just refer the to that mod.

[wzhec]

这是来自QQ邮箱的假期自动回复邮件。   您好，我最近正在休假中，无法亲自回复您的邮件。我将在假期结束后，尽快给您回复。