[Talk-us] Chesapeake Bay Bridge reversible lanes

[Paul Johnson]

On Mon, Apr 10, 2023 at 12:49 PM Nick Santos <nick at nicksantos.com> wrote:

> Caveat - I'm not an expert in this, but seeing no other responses, thought
> I'd chime in with another example that might be worth examining.
>
> The Golden Gate Bridge also has a reversible lane. It looks like it
> started by using a lanes=3 and lanes:both_ways=1 tagging scheme similar to
> what you outlined, but someone converted it a few years ago to use lanes=3
> and lanes:conditional=4 @ ..., which seems like a nice way to be able to
> specify when the lane flows each direction with a syntax commonly
> understood by consumers of OSM data.
>

Not the same situation.  I was going to say that's not even good tagging
for the Golden Gate Bridge but it seems they've switched to using a hard
barrier instead of traffic control signs and signals since I last drove it,
so, for the Golden Gate Bridge's extremely strange way of handling
reversible lanes, yes, this would be correct, albeit a very unusual edge
case where the number of lanes physically changes.


> I don't know enough about how widely picked up conditional lanes or
> both_ways lanes are by routers, but thought I'd mention it as another
> example in case it's useful. Here's a link t
> <https://www.openstreetmap.org/way/595194543/history>
>

Honestly anything that isn't able to understand conditional restrictions,
lane direction and lane access, isn't really suitable for the task of lane
guidance.
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