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Drivers have been getting a peek at some overhead signs during testing for Interstate 77 express lanes.

Will the soon-to-open express lanes on Interstate 77 ease congestion?

As local legislators continue to explore avenues for wresting control of the lanes from a contractor whose deal with the state allows it to manage and collect tolls along the 26-mile stretch for 50 years, many critics of the project continue to predict that it will do little to help move traffic through the Lake Norman area. Additional free lanes, they argue, should have been the remedy for the interstate’s perpetual clogs.

Before I go any further, let me say that, based on the announced rates, I expect to have little or no use for the toll lanes myself. I’m also offering no opinion on whether express lanes were the best option, if the state should eventually buy out the U.S. subsidiary of Spanish construction giant Cintra and manage the lanes itself, or if one of the two toll lanes in each direction should be converted to a free lane, as has been proposed.

In other words, I have no dog in this fight.

But I did find it fascinating when the subject of managed lanes turned up recently in a seemingly unexpected place: the pages of the respected international science journal Nature.

In an article, Peter Cramton and Axel Ockenfels, economics professors at the University of Cologne in Germany, and R. Richard Geddes, professor policy analysis and management at Cornell University, not only advocate for tolling, they argue that “dynamic,” or usage based, systems to charge drivers like the one that will be employed on the I-77 express lanes are “the only way forward” for addressing congested roadways.

Demand vs. capacity

Research has shown that adding new lanes to highways does little to ease congestion over time because the increased capacity ultimately generates a corresponding amount of additional traffic volume. But let’s put that assumption aside for now, along with questions of whether toll lanes are a fair and equitable solution from the perspective of Lake Norman area citizens and businesses. That’s a relevant discussion to have, but it’s separate from the science related to moving motorists on a highway.

In the Nature article, the crux of the authors’ thesis is that we often disagree on remedies – in our case locally, free lanes vs. toll lanes – because we’ve reached different diagnoses of the problem.

Local advocates for free, general purpose lanes believe that the solution to congestion is creating enough highway capacity to accommodate the amount of traffic generated during peak periods. That would be achieved, they argue, by adding enough free lanes to move traffic when the most vehicles are on the highway.

In other words, the problem that needs to be fixed involves the size of the pipe through which traffic flows.

In their Science article, however, the authors essentially argue that a general-purpose lane solution is based on the wrong question. What we should be asking, they say, is not how to keep traffic moving during the busiest times, but rather how to move the most vehicles through the area over time.

In other words, the problem isn’t the size of the pipe, but rather a lack of control over how much comes through the pipe and when.

In the authors’ view, dynamic tolling is a valve that constantly adjusts to maintain a consistent flow without ever exceeding the pipe’s capacity.

Rather than manipulating capacity to meet demand (as adding general-purpose lanes would aim to do) dynamic tolling looks to manipulate demand to consistently match capacity.

Making motorists pay to drive leads many to change their habits by altering their work hours, taking a bus or carpooling, or even moving closer to their jobs or other places they go on a daily basis, according to the authors. All of those scenarios lead to less demand at peak times without adding capacity.

The authors compare this affect to the impact of energy prices. When they are high, consumers are more likely to conserve energy.

“Lexus Lanes”

I recently bought a used hybrid car, a model that the manufacturer is phasing out this year. Other hybrids and smaller sedans are facing similar fates. Why? Because consumers believe gas prices will remain low, so fuel efficiency is less of a priority.

Cheap gas has the same effect as adding lanes to a highway. It encourages consumption. Expensive fuel, however, manipulates consumers the same way dynamic tolling does, by encouraging them to adjust how and what they drive.

The cost-driven cause and effect of dynamic tolling feeds the “Lexus Lanes” label applied to the I-77 scheme by critics who insist – accurately, I believe – that drivers who can’t afford peak tolls will be the ones forced to adjust their routines, while those with means will pay the cost, however high, without being inconvenienced.

The authors say more research is needed to determine the level of inequality created by dynamic tolling. But they also suggest that even those who can’t afford to pay peak tolls will have the benefit of getting where they’re going faster because the peak-time payers are freeing up capacity in the free lanes.

“No way that will work!”

Cramton, Ockenfels and Geddes write that dynamic tolling has won over early critics in Europe, including in Stockholm and Milan, Italy, where citizen sentiment shifted to overwhelmingly supportive of the concept after congestion was reduced.

Will we also look back in a few years and wonder what all the hullabaloo was about leading up to the opening of the I-77 express lanes, much like with the “diverging diamond” at Exit 28 in Cornelius and the multiple-turn traffic pattern for accessing U.S. 21 from N.C. 73 in Huntersville?

Variations on “That’s the stupidest thing I’ve ever seen!” and “There’s no way that will work!” were common refrains during construction on those projects. But they did ease congestion – by controlling the movement of traffic rather than by widening roads (particularly on the Exit 28 overpass, where the roadway takes up LESS surface than before to make room for a protected pedestrian crossing).

Again, I’m not here to defend or criticize the managed lane project. But I’m anxious to see how reality will square with theory.

John Deem is editor of Lake Norman Publications.


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