Bob CollinsFor reasons that remain unclear — there weren’t that many accidents — rush hour traffic in the Twin Cities Monday evening was a nightmare, particularly the stretch of Interstate 35W southbound where someone once thought it a fine idea to design an off ramp to Interstate 94 westbound that intersected two other ramps.
The more we pave over the Twin Cities with highways, the worse the traffic seems to get, and we don’t even get bragging rights out of the deal for our horrible traffic.
In a survey released Tuesday, Minneapolis ranks only 24th among the nation’s urban centers for congestion, according to INRIX’s Global Traffic Scorecard.
Boston ranks No. 1, although its congestion has dropped 10 percent from last year while Minneapolis is up 4 percent, still good enough for our fair city to rank 134th in the world.
It says the average cost in wasted time per driver is about $1,000 a year. Drivers spend about 70 hours a year in traffic jams during rush hour compared to other times of the day.
That’s still a far cry from Bogota, Colombia, where drivers spent 272 hours going nowhere. Minneapolis drivers lose $1.3 billion a year to traffic, the report said.
We’re no Singapore, though. The report gives credit to the city which is among the most populated in the world, but ranks relatively low on traffic congestion because of “aggressive policies” against driving.
To be fair, the annual report has its critics. StreetsBlog, for example, noted that its methodology penalizes older, denser cities. And its definition of congestion is flawed.
The definition of congestion is a novel and expansive one: Any time travel speeds fall below 65 percent of free-flow speeds, Inrix regards this as being “congested.”
Inrix says it determines free-flow speeds using actual traffic data. As we and other have noted, this approach often results in using speeds that exceed the posted legal speed limit for a roadway as the baseline for determining whether a road is congested.
For example, if “free flow” speeds on a posted 55 mile per hour road are 60 or 65 miles per hour, Inrix would presumably use this higher baseline for computing congestion. This has the curious implication that the inability of a motorist to engage in an illegal behavior constitutes a “cost.”
Also: its worth noting that roadways achieve their maximum throughput (number of vehicles moved per hour on a roadway segment) and speeds that are usually much lower than free flow speeds. (At higher speeds, drivers increase their following distance and the road carries fewer cars per hour).
So in many cases, these lower speeds (say 40 miles per hour on a 55 mile per hour roadway, where free-flow speeds are 60 miles per hour), may actually be more efficient.
StreetsBlog also says the report inflates the cost of being stuck in traffic.
