[Talk-us] Prioritizing multi-banded route designators (multiple overlaps) on ways: the "Principal route designator" concept

[Shawn K. Quinn]

On Sat, Dec 21, 2013, at 12:46 PM, Peter Davies wrote:
> The question is how to handle US roadway routes that are double, triple
> or
> even quad-banded, having multiple route designators.  Some OSM mappers
> call
> this topic "route overlaps."  I might call it "information overload." On
> most maps, renderers simply show ALL the shields. But is it helpful to
> have
> roads peppered with conflicting information about the route number?  Who
> gains by knowing that Western Avenue, Augusta, Maine is US 202, ME 11, ME
> 17 and ME 100?  Isn't this really confusing and unhelpful for most map
> users?

I find these helpful when giving directions. "Follow Texas 6, which will
involve exiting the freeway and turning right / turning left and getting
on the freeway." (Part of US 290 in northwest Harris County is also
signed Texas 6.) "Stay on US 290, which will involve a cloverleaf exit
ramp when leaving Brenham." (US 290 and Texas 36 are both signed on this
one particular stretch of road.) etc.

What appear to be "rubbish numbers" are useful to those following those
numbered routes.
 
> Now, if it's confusing on a map, just think how confusing it is in a
> navigation system or a traffic event info system.  "Look out for a crash
> on US 202 eastbound / ME 11 northbound / ME 17 northbound / ME 100 eastbound
> (Western Avenue) in Augusta."  We need to know which route designator is
> the most important one, and to use mainly or only that one when talking
> to drivers.

In some cases it's not obvious *if* there is a primary route designator.
A lot of the time, to me, the primary designator will be the highway I'm
following, or the highway the recipient of my directions should be
following. I will admit the locals prefer to call it US 290 in the
former case, but the latter is a bit more ambiguous, as is the overlap
of Texas 71 and Texas 21 near Bastrop.

I'm guessing in your case US 202 is probably what you're calling the
primary. A navigation or traffic event info system might be able to make
an intelligent announcement based on the most likely numbered route that
one is following. I certainly wouldn't want to hear *just* US 202 in
that announcement, though, and think "oh, I'm not taking that route I'm
taking ME 17 -- oh, that's right, there's this one block of overlap, so
maybe I am taking US 202."

-- 
  Shawn K. Quinn
  skquinn at rushpost.com