Join Date: Jul 2005
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I only just spotted the last post. I know it dates back to November, but it's still an unanswered question
TMC seems to give you a bit of everything. I think the data is compiled largely from available, published traffic information (the kind that you'd get on radio traffic bulletins) though I believe certain vehicle fleets have trackers fitted, automatically relaying any problems that their vehicles encounter. It's been a while since I looked into it, but I recall National Express Coaches and Eddie Stobart were two names that were mentioned in the early days. The data concentrates on main and trunk roads, but it's also often includes planned closures of even the tiniest and least significant roads, as well as accidents and hold-ups if they manage to make it into the news. So you get a bit of a mix really.
The alternative is TrafficMaster, which is a separate unit and monitors motorways, major A-Roads and a few minor A-Roads only. This is a totally automated 'live' system that operates off the little blue cameras that you see at the side of the road. The quality of the TrafficMaster data is vastly superior to TMC in my opinion, and when the two give me conflicting information (and they regularly do) I tend to trust TrafficMaster, as it's much more likely to be right. But TMC is definitely still worth having, and is a lot better than relying on RDS or having no information at all.
Currently in Horatio's garage:
2010 Laguna III Initiale.