[Tagging] maxspeed=signals

[John Sturdy]

On Tue, Jun 26, 2012 at 3:59 PM, Paul Johnson <baloo at ursamundi.org> wrote:

> In the US, the most common variable speed limit scenario is a school zone.
> Rules for when the lower limit applies varies.  Some are certain hours of
> the day and only on school days, others are year round whenever children are
> present, and others still are based on signal indication.

Those sound fairly predictable, although not necessarily easy to parse
and use in routing applications.

> On Jun 26, 2012 5:47 AM, "John Sturdy" <jcg.sturdy at gmail.com> wrote:
>
>> As far as I know, variable speed limits tend to be used in areas prone
>> to heavy congestion, so routing applications should probably assume
>> it's a slow road (at least during the daytime).

The ones I'm thinking of vary according to traffic conditions,
attempting to slow down traffic that is approaching a congested
section of road, apparently in the hope that rather than arriving at
the congestion and adding to it, the approaching traffic will arrive
after the congestion has dispersed.  (See
http://en.wikipedia.org/wiki/Traffic_wave)

So, this is only coarsely predictable.

__John