Local News

Model shows three lanes better than two for I-40/440 project

Posted June 20, 2013
Updated October 25, 2013

— The North Carolina Department of Transportation originally said the contractor working on the I-40/440 Rebuild – the massive project to rebuild an 11.5-mile stretch of Interstates 40 and 440 – would need to keep at least two lanes open in both directions along the roadway when construction begins in January.

But when traffic engineers at North Carolina State University plugged that into a model, it wasn't pretty.

“We actually would have predicted a 10-fold increase in travel time,” said Bastian Schroeder of N.C. State’s Institute for Transportation Research and Education

The model predicted that backups in the evening would start on I-40 eastbound around Airport Boulevard and continue all the way through the work zone.

But the contractor, Granite Construction, says it can keep three lanes open, which would confine delays mostly to the work zone.

With three lanes open, the model shows the impact on traffic is much less severe.

Now, the typical travel time for either direction on I-40 between Airport Boulevard and N.C. Highway 42 is about 27 minutes.

Assuming three lanes are open and 20 percent of drivers would choose an alternate route, the model shows the morning commute on westbound I-40 from N.C. 42 to Airport Boulevard would take about 38 minutes.

The model says the evening commute would be the toughest – eastbound I-40 would take an estimated 55 minutes.

The morning commute may be worse on alternate routes. According to the model, travel times on routes such as U.S. Highway 70 Business, Hammond Road and Rock Quarry Road could increase at least 30 percent.

Schroeder says this model data is a worst-case scenario. The contractor says it won't build in the entire work zone at once. It will complete the project in phases, which will help with congestion.

The models also don't take into account telecommuting and carpooling, which would reduce congestion.

“If we get everybody to carpool, then things will be better than they are today or at least the same as they are today,” Schroeder said.

Schroeder and his colleagues are working on new model data to determine the impact of the contractor's plan to work in stages.


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  • djofraleigh Jun 21, 2013

    The headline is rather common sense, isn't it?

    As for the comments about 264 bypass having to reduce lanes, well, that was to defeat the selfishness of human nature, to stop the fly by on the right drivers from jumping ahead and moving back to a slow those others "good" drivers.

  • WRAL_USER Jun 21, 2013

    @ Jeff

    ...and that is why 3 lanes are better than 2? Baiting a little?

  • WRAL_USER Jun 21, 2013


    Yea, NC DOT should use that "plain thinking" you espouse rather than that "expensive" scientific modeling, unless they actually want to know what will happen... WOW!

  • jeffjohnson123 Jun 21, 2013

    Maybe if we had fewer non-tax paying people on the road, there would be road-a-plenty for those of us who DO pay taxes.
    Does the federal government return extra funds to the states for its inability to enforce its laws? It should.

  • copperino Jun 21, 2013

    outhousecat: Did you actually travel the Clayton bypass when it was 3 lanes? All the "me-me" inconsiderates jumped in the right lane, and when they forced their way back into the main travel lanes, it backed up traffic worse than it is now. As bad as it is now, it's actually better than it was before. This is why we can't have nice things.

  • outhousecat Jun 21, 2013

    Obviously these aren't the same geniuses that decided that two lanes are better than three on I-40 at the Clayton by-pass. Whoever came up with that little plan should have been fired on site.

  • Cleanup on Aisle Cool Jun 21, 2013

    Listen people - you might learn something.
    Shutting down 1/2 the lanes on I-40 produces not twice the traffic, but a 10-fold increase in traffic. There is not a linear relationship, as one would predict assuming 100% merging efficiency. The nature of this relationship is what was being explored, plus a challenge of the DOT's assumptions. Well done, NC State.

  • B74 Jun 21, 2013

    What about the sections that are already three lanes - those won't have lane closures?

  • Cock a doodle doo Jun 21, 2013

    Well said jcthai!

  • ConservativeVoter Jun 21, 2013

    Wow those kids at NCSU are rocket scientists.

    Anybody with a brain would know this without the expensive model being run.