[Tagging] Slow vehicle turnouts

Kevin Kenny kevin.b.kenny at gmail.com
Mon Sep 10 19:23:13 UTC 2018

On Mon, Sep 10, 2018 at 2:38 PM Paul Johnson <baloo at ursamundi.org> wrote:
> I see it as a variation on no turn on red/turn after stop OK on red dichotomy.  Not really significant enough to bring up in the map data specifically, so long as the signal itself is mapped.  And the single white line seems to not be of special significance in most cases, only meaning that you need to use additional caution when changing lanes (as opposed to double white lines, where lane changes in one or both directions is prohibited).

For what it's worth, New York appears to have used a double broken
white line to separate climbing lanes. (Source: personal observation
in the field.) The drivers' manual does not discuss this unusual
marking. There is a subtle difference in the signage. The signs read
EXCEPT TO PASS" for a 'normal' multilane road. The implication appears
to be that you don't have to move to the right into a climbing lane if
nobody is overtaking.

The double-broken-white-line convention last appeared in the 2005 NY
State MUTCD. There's a 2015 order
that prohibits the practice, and uses broken, solid, and double white
lines to indicate that lane crossings are permitted, discouraged or
prohibited respectively - in conformance with the federal MUTCD.
Nevertheless, there are a fair number of roads that have not been
restriped and still bear the old double-broken-line convention.
Restriping projects in some cases appear not to have removed the old
paint, giving rise to a broken white line that is unusually wide.
MUTCD permits painting wider lines than standard, for emphasis. New
York uses the wide lines to set off dedicated lanes (HUV lanes,
turning lanes, merge/exit lanes, or lanes committing the driver to one
side of a route split.)

There were also once some lanes that were set off with white
partial-barrier lines (broken and solid line in parallel), which
appeared to allow merging into a climbing lane but forbid leaving one
once committed to it. These are also forbidden under the 2015 order.

A 90%-good solution to all of these combinations is simply to indicate
the number of forward, backward and both_ways lanes. Some of the finer
details fall into "Don't map your local legislation'

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