NMA E-Newsletter #162: Slowing Down to Speed Up


They call it “Rolling Speed Harmonization,” but it’s just Command and Control traffic enforcement with a more pleasant-sounding name.

Rolling Speed Harmonization refers to recent efforts by the Colorado Department of Transportation (CDOT) to relieve congestion on a 39-mile stretch of I-70 west of Denver. This corridor becomes congested with weekend ski traffic exacerbated by narrow mountain passes and bottle-necking at the Eisenhower Tunnel.

CDOT partnered with the Colorado State Patrol and local police agencies to run the program. The plan called for groups of passenger vehicles to queue up behind police cruisers that then led them through the problematic stretch at lower than posted speeds. Waives of traffic under forced police escort departed from a designated starting point every five to 10 minutes during peak travel times.

According to CDOT, the operation was intended “to regulate speed and reduce turbulence providing congestion relief measures with safety benefits.” Off-duty police officers were paid overtime to drive the pace cars.

Despite driver complaints over slower speeds, news accounts labeled the effort a success. One commentator even gushed over the scheme’s “subtle beauty of system optimality.” CDOT reported “strongly favorable” results from its initial tests, citing strong driver compliance, reduction in speed differentials and reduced travel speeds overall. No wonder they dubbed it Operation Snow Tortoise.

Speed harmonization is nothing new. Traffic planners use various techniques including metered ramps, variable speed limits, and temporary shoulder lanes to even out traffic-flow and reduce congestion. The mantra among those in the know is: “You have to slow down to speed up.” They compare speed harmonization to pouring rice through a funnel. The slower the rice is poured, the faster it travels through the final. Pouring it all in at once clogs up the funnel.

Sounds logical. The only problem is it doesn’t work. CDOT suspended the program in late January after high traffic volumes overwhelmed the system, producing massive backups at the Eisenhower Tunnel. A CDOT spokesperson said the program may resume later in the season but admitted the only real solution is to widen the highway.

Using police cars as rolling roadblocks has been around for years—sometimes in response to road hazards and sometimes for speed enforcement. The New Jersey State Police tried pacing on the New Jersey Turnpike to force compliance with the 55 National Maximum Speed Limit. The program was abandoned after two years when it was judged ineffective and potentially dangerous. And back in the 1960’s the Connecticut State Police used to drive around with giant speedometers on the roofs of their cruisers.

What gets left out of the discussion is the effect of speed harmonization on drivers. Ineffective measures, or measures that do more harm than good, result in increased driver frustration potentially leading to greater disruptions on the road. Call it government-sponsored road rage.

Common-sense approaches, like Lane Courtesy (slower traffic keep right) and proper establishment of speed limits, should be the primary focus of any efforts to improve traffic flow and relieve congestion.

The experts need to acknowledge that drivers aren’t like grains of rice after all… or maybe they just need to try a bigger funnel.

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