Learning to Love Your Traffic Engineer – Speed and Volume
Wednesday, November 20 by JerryFoster
Unlike residents, our traffic engineers prioritize speed and volume over safety and low cost ? why? It?s how they were trained.
We?re long past the era where roads provide orders-of-magnitude improvement, e.g. from walking to motoring, but policy still encourages speeding, e.g., engineers design for 5-10mph over posted speed, so 74% of drivers on Rt 1 in Plainsboro exceeded the speed limit recently.
Going faster means getting there faster, right? Only if you?re on the mythical open road – in densely populated New Jersey, we have traffic.
Speed can work against getting there faster in traffic, since cars stay further apart – the best volume throughput is at 30-46mph. Improved signal coordination and speed harmonization allow people to get there faster even though they?re going slower, by delaying the onset of stop-and-go congestion.
Historically, traffic increased year after year, but in 2004 per capita volume (vehicle miles traveled) declined (!), followed in 2007 by a total volume decline as the recession took hold.? Though the Great Recession ended June 2009, total volume remains at recession levels, and per capita volume continues to slide.
Is it the end of ?build it and they will come?? If so, engineers will have one more reason to change their priorities. In our next installment of Learning to Love Your Traffic Engineer we?ll look at safety.
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