[pgrouting-users] pgrouting and road traffic congestion

Stephen Woodbridge woodbri at swoodbridge.com
Fri Mar 1 05:40:40 PST 2013

Daniel's suggestion is good.

Here is how you want to think about the problem:

1. you have a bunch of segments
2. you have average speed based on traffic at different times of the day 
for various segments
3. when you request a route, you specify a time
4. then when you select your segments and costs you factor in the 
average times

You might not have average times for all segments based on traffic info 
so consider this query or one like it:

select 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

So this query assume you have a segments table with a column "speed" and 
the "traffic" something like:

id, gid, time1, time2, speed

If you have a speed in the traffic table it will get used otherwise you 
will use the default time associated with the segment. If you have 
historical average speed data then the traffic table can be static, or 
if you want some that routes based on current information and you have 
access to real-time traffic sensor speed data that can be feed 
dynamically into the traffic data and the system works either way.

I have done both of these for different clients in the past.

-Steve W

On 3/1/2013 2:34 AM, Daniel Kastl wrote:
> Time-dependent shortest path might be what you're looking for:
> https://github.com/pgRouting/pgrouting/wiki/Time-dependent---Dynamic-Shortest-Path
> Daniel
> On Fri, Mar 1, 2013 at 12:27 PM, Muhammad Iqnaul Haq
> <iqnaulhaq at gmail.com <mailto:iqnaulhaq at gmail.com>> wrote:
>     Hello all
>     I'm working on my project proposal, I want to make an alternative
>     route where there was an traffic congestion/traffic jam in several
>     road at different time. For example at 7 am the traffic congestion
>     in Road A is very high(bad), the drivers may choose their
>     destination and the application built with pgrouting will show
>     another faster/shortest route to avoid the traffic.
>     Is there any suggestion or any kind of application that has been
>     made similar with my idea?
>     thanks for your attention
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> Georepublic UG & Georepublic Japan
> eMail: daniel.kastl at georepublic.de <mailto:daniel.kastl at georepublic.de>
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