Traffic congestion in the Manhattan core is rebounding. Travel-speed data culled from taxicab GPS and released last month by City transportation and taxi officials suggest that average motor vehicle travel speeds in the Central Business District fell by 8.5 percent from 2012 to 2014. The slowdown follows years of flat or even rising speeds — a phenomenon that predated the 2008 financial collapse and undermined congestion pricing proposals by making car, bus, truck and taxi travel in the heart of the city a little more efficient and predictable.
The speed data were issued during the recent Uber controversy, but they bear on a host of other policy issues including Vision Zero, cycle infrastructure, and bus priority signals and lanes. To inject some rigor into these discussions, I’ve created a special section of my Balanced Transportation Analyzer spreadsheet to approximate various factors’ roles in re-congesting the CBD. My preliminary findings are summarized in the graphic. (Readers interested in a deep dive should download the BTA and navigate to the new tab, CBD Congestion.)
The task is to account for an “adjusted” 10.5 percent drop in CBD travel speeds. That figure tacks 2 percentage points on top of the observed 8.5 percent reduction to reflect the fact that the 20,000 a day decrease in motor vehicle entries from 2012 to 2014 also reported by DOT should have increased CBD travel speeds by 2.0 percent. Here are details: