I-526 is a congested highway at peak commute times. There’s no room for debate on that point. But there is plenty of room for debate about how best to alleviate that congestion.
And with the S.C. Department of Transportation working on a plan to improve the western portion of the highway — from North Rhett Avenue in North Charleston to Paul Cantrell Boulevard in West Ashley — now is the time to get things right.
We haven’t yet seen any formal proposals for I-526 upgrades, but the assumption is that they will mostly involve adding an extra lane in each direction and somehow boosting the capacity of the interchange with I-26.
That’s not a particularly inspiring plan.
Simply expanding the existing 526 corridor — at an estimated cost of $1.1 billion — wouldn’t give commuters anywhere new to go. They might be able to drive faster and more easily bypass slower vehicles, but their commutes will cover the same distance.
A single wreck along the way would still bring everyone to a crawl.
In other words, a straightforward widening would be one of the more expensive road projects in South Carolina history to get a modest decrease in average travel times for commuters who would still be left vulnerable to routine hold-ups from car crashes and other problems.
And that decrease in travel time would be more marginal than frustrated 526 commuters deserve.
A recent review of multiple nationwide studies on highway expansions found that every 1% increase in road capacity generated up to a 0.7% increase in traffic almost immediately and about a 1% increase in traffic in the long-term on average.
It’s a well-documented concept called induced demand.
Basically, commuters are sensitive to traffic and they adjust their behavior whenever possible to account for it. If traffic is bad on a daily basis, they might leave earlier to go to work, for example. But when traffic eases up, the incentive to avoid traffic disappears.
Eventually enough people change their behavior and everything is back to square one, albeit having effectively wasted $1.1 billion in taxpayer money along the way.
Induced demand works in the other direction too. In fact, the Charleston area recently got the chance to run a natural experiment when half of the Wando Bridge — part of 526, incidentally — was shut down between Mount Pleasant and North Charleston for a few weeks last year.
At first, traffic was apocalyptic. But after a few days, people adjusted. Traffic was still worse than normal, but not unlivable, especially considering that one of only three major ways out of Mount Pleasant had been completely shut down.
So if widening isn’t an ideal solution, we ought to consider more creative alternatives.
It might be possible, for instance, to bridge Bees Ferry Road to Dorchester Road near I-526, which might also help keep cars from a growing part of West Ashley off of the already congested and impossible to widen Ashley River Road.
Thinking in terms of new road connections rather than a wider existing road would still cause induced demand, but it would decrease the fragility of the larger regional transportation network. Planned well, they could also open up routes for future transit lines and improve bicycle and pedestrian connectivity.
Transit in particular is one of the only realistic and sustainable ways to handle traffic congestion long-term as the Charleston region continues to grow.
It’s worth keeping in mind that $1.1 billion would be enough to roughly quadruple in size a planned bus rapid transit system, connecting it to West Ashley, Mount Pleasant and other areas underserved by existing bus service.
It’s not in anyone’s best interest to have daily traffic jams along I-526. It’s not in anyone’s best interest to spend more than a billion dollars on a supposed solution that won’t fix much either.