[pgrouting-users] pgRouting and traffic congestion

[Stephen Woodbridge]

On 3/3/2013 7:14 AM, Muhammad Iqnaul Haq wrote:
> Hello Mr. Stephen
>
> I'm iqnaul who asked about pgrouting and road traffic congestion in
> pgrouting lists. I'm really thank you for your explanation. I want to
> ask you is it possible to identify the traffic jam/congestion as a
> barrier in pgrotuing table? so that when there is a jam the system will
> automatically suggest another road segment to avoid the jam.
> Do you have the websites that you made for your clients about this system?
>
> thank you
>
> warm regards

Hi Iqnaul,

This link is to a reference site I set up for one of my clients. It 
shows just a simple pgRouting installation but I have added an 
enhancement for the driving direction. The sites that I added traffic 
too are not publicly accessible sites.

http://tinyurl.com/3vnufmh

You can add general area avoidances by using some SQL on how you select 
edges. Say you have a table of lines and/or polygon that you do not want 
your routes to cross over, ie you have to route around these 
obstructions. Then you could modify my previous SQL to look like this:

select a.gid, coalesce(b.speed, a.speed), a.the_geom
   from streets a
        left outer join traffic b on a.gid=b.gid
  where mytime between b.time1 and b.time2
        and a.gid not in (
            select a.gid
              from streets a, avoid b
             where st_dwithin(a.the_geom, b.the _geom, 0.0));

There may be more efficient ways to do this but basically you want to 
eliminate the edges for the areas that you want to avoid.

-Steve