Statistics Support Optimism for Airline-Siegen Experiment

3/04
The innovative continuous flow intersection (CFI) the City-Parish will try to alleviate congestion at Airline Highway and South Sherwood Forest Boulevard and Siegen Lane comes to Baton Rouge with impressive statistics.

According to an article, written by Mike Bruce, ABMB Engineers Inc. principal in charge of CFI for “Lone Star Roads,” the Texas Department of Transportation and the Federal Highway Administration’s publication, the CFI will allow as much as a 40 percent increase in traffic flow, compared to a conventional intersection.

The CFI also has the potential to decrease the intersection’s delay from 255 seconds to 21 seconds.  The change represents improving a wait exceeding four minutes to one of only seconds.

Perhaps the most impressive statistic is the difference in the average line of cars waiting at the intersection.  With a conventional arrangement, the line runs approximately 630 feet.  The CFI has the potential to shorten the line of idling cars to 36 feet.

According to Bruce, the CFI is succeeding with helping Mexico with its traffic snarls at between 40 and 50 locations.  He says the new intersection is providing significant relief to congestion at an interchange in Maryland, outside the Washington, D.C. area too.

The Maryland project received the 2002 Francis B. Francois Award for Innovation from the American Association of State Highway and Transportation Officials.

Under the CFI design, left-turning traffic from Airline Highway will turn onto something like a service road before it reaches the intersection with Siegen Lane and South Sherwood Forest Boulevard.  By reducing the volume of turning traffic at the actual intersection, the through-traffic will have more green-signal time to continue moving through the interchange.

In other words, all traffic keeps moving better.

The improvement comes at a significantly lower cost that the usual lane-widening and overpass alternatives.

Bruce explains, “When you add lanes, you have to work with getting rights of way and when you build overpasses, you’re talking about tens of millions of dollars right away because you’re talking about separate grades.  The CFI requires no additional rights of way and it comes at-grade.”

Bruce says at-grade means the changes can be implemented without altering the existing road’s grade.

Gary Beard, state representative – District 69 and a trained civil engineer, says the CFI could save several million dollars in the project to improve Airline Highway.

Other states considering incorporating CFI into their transportation plans include Arizona, Arkansas, California, Maryland, Mississippi, Nevada and Ohio.