Toll lanes with carpools and buses can reduce highway costs and congestion
DENVER, Colo. – For crowded highways, such as I-70 between Denver and Summit County, managed toll lanes are better than general access lanes at alleviating congestion.
That’s one take-away from a white paper released today by the Southwest Energy Efficiency Project. The study, Managed Highway Lanes in Colorado, says attempts to solve traffic overcrowding by adding free lanes to highways simply generate more traffic.
Will Toor, director of transportation programs at SWEEP, points to the T-Rex expansion of I-25 in metro Denver completed in 2006. The easy-driving conditions were short-lived. A recent Denver Regional Council of Governments report found that severe weekday congestion plagued the heart of the expanded roadway by 2011.
Free-flowing highway lanes can carry up to 2,000 vehicles an hour, the SWEEP report notes. But when a lane gets overloaded, such as on I-25, stop-and-go traffic can reduce traffic capacity by almost half while doubling greenhouse gas emissions and air pollutants.
Colorado already has a managed toll lane as part of I-25 north from downtown Denver and U.S. 36 to Pecos Street. Other managed toll lanes are under construction on U.S. 36 to Boulder, while several other toll lanes are being considered for several highway segments, including I-70.
But SWEEP also sees a social equity issue in managed toll lanes. The non-profit finds that the top third of households by income use toll lanes almost eight times more than the bottom third.
To make the most of managed toll lanes, Toor says that they need to be opened more to carpoolers but also buses—as is planned on the U.S. 36 toll lanes that will be opened in two years.
This is a message that also needs to be kept in mind on I-70 through the mountains, says Toor. There, C-DOT is considering using shoulders of I-70 in the Idaho Springs-Georgetown area for toll lanes during congested weekend periods. Those using the toll lanes would be assured of going faster than general traffic, a minimum of 45 mph.
An even more ambitious tolling enterprise that results from additional construction, such as a third bore through the Continental Divide, would also probably require a managed toll lane.
In these cases, says Toor, access should also be provided to car poolers. Given that ski traffic already has a high proportion of car-pooling, unlike the single-occupancy vehicles of urban commuting, the minimum for carpooling would have to be edged higher, he says. SWEEP also wants to see buses employed along I-70.
Colorado has seen public-private partnerships toll lanes as a key way to pay for transportation expansions. But the P3 approved by the Colorado Transportation Commission in February came after great controversy. Two bills introduced into the Colroado Senate on Friday by State Sen. Matt Jones would place restrictions on such P3s.