A data question really, though there may be a useful geo-processing solution.
Context: I am calculating "drivetime" catchment areas using PgRouting and OSM / OSM2PO. If my employer/client is to use this as information for decisions, then I think the base data needs to be good.
Problem: The fact is that in a large city say, London speed limits exceed traffic speeds due to congestion. Therefore, my polygons are not really valid (except at times of low activity).
Question: Thus, I'd greatly value any help (all ideas good) with how to update my OSM speeds on an area by area or road by road basis. (E.g: Is there crowd-sourced data (from mobiles)? Can I get access to traffic flow data? Has somebody else tackled this?).
Best Answer
Waze is one route - but uses Ordnance Survey data (at cost) in the UK.
http://www.waze.com/wiki/index.php/United_Kingdom
http://www.waze.com/livemap/ (US only)
Sabre Roads is another project (waze links to this)
"perhaps the most complete archive of information on the British and Irish road network"
http://www.sabre-roads.org.uk/wiki/index.php?title=Main_Page
Trafficmaster (at cost)
Those blue long cameras mounted on blue poles is your best source: There are 5,200 cameras - they monitor congestion live http://www.trafficmaster.co.uk/content/1/60/real-time-traffic-information.html
(you will need an account and they will charge you to access to the live data - trafficsales@trafficmaster.co.uk)