HCM wrong - peak flows at 60mph

A group of engineers led by Pravin Varaiya at UC Berkeley’s Institute of Transp Studies has been looking into the data generated by District 7’s 20,000 loops. They discovered that peak flows – 2,000 cars per lane per hour –actually occur in the Los Angeles area at 60 mph, not 45 mph as the highway engineer’s ‘bible’ the Highway Capacity Manual says. Varaiya says the HCM seems to be “pure formula, wrong, based on no empirical data.”