Can Historical Vehicle Probe Speeds from Private Sector Vendors be used to Flag Segments with Congestion on Interrupted-flow Arterial Highways?

摘要

Transportation agency operators and planners can now purchase real-time orhistorical vehicle speed data from private-sector vendors covering very large regionalhighway networks. The accuracy of these data products is fundamentally important;however, operators and planners view “accuracy” through different lenses, and whilefreeway data quality has been comprehensively studied, authoritative conclusions aboutsuitability of these sources for interrupted-flow arterial monitoring have not yet beenpublished.Thus, working from a planner’s perspective, the author has taken a macro-levelfirst-cut look at the question. For test highway segments where he already knew wheretypical daily bottlenecks were located, he calculated typical peak-period delay values –segment-by-segment – from default “historical” speed data donated by a private vendor.He juxtaposed these delay calculations against his lists of confirmed daily bottlenecks –the sources for these lists were periodic historical surveys using large sets of time-lapseaerial photography (TLAP), acquired during 24 mid-week morning and evening flyovers.He then refined calculation rules and experimented with various threshold delay values(above which segments would be flagged as “congested”), until he found the bestcorrelation between “congested” ratings generated by the two methods.Reviewing these lists, he found evidence that private-sector speed data oninterrupted-flow arterials may already be good enough to classify segments as“congested”, with varying degrees of severity and duration. After more rigorous researchto confirm, planners may have a more affordable way to calibrate computer models,screen large networks for likely bottlenecks, confirm where long-term degradation isoccurring, or prove the benefits of investments.