Intersecting Interests

Local transportation engineers are hitching their wagon to a novel traffic--control approach

A Baton Rouge engineering firm is pushing an innovative yet rarely used idea for improving traffic that the company hopes will boost its stature nationwide-if it works.

Mike Bruce of ABMB Engineering says so-called "continuous flow intersections," or CFIs, reduce traffic congestion by reconfiguring busy crossroads to allow left-turning and opposing through traffic to move at the same time.

Try that at a regular intersection and see what happens.

Bruce, co-owner of the firm and "principal in charge of CFIs," says there are 45 of the odd-looking intersections in the world, the vast majority in Mexico. Only two are in this country: one in Long Island, the other in Maryland.

Louisiana could be next: the state Department of Transportation and Development has hired Bruce's firm to design a pilot project for Baton Rouge at one of the Capital City's most notorious traffic black holes: Airline Highway and Siegen Lane/Sherwood Forest Boulevard.

Building one here would make Baton Rouge and ABMB pioneers in what Bruce thinks will be the nation's steady migration toward continuous flow intersections as an economical traffic solution. The dream is on hold, at least temporarily, until DOTD puts the project out to bid-again. The agency's first call for construction bids attracted exactly one response: a bid $1.7 million over the agency's $3.7 million estimate.

It came from Coastal Bridge Co., whose vice president, Ed Milner, says the state's estimate was too low given the time constraints, late-completion penalties and heavy traffic in the area. DOTD will "repackage" and readvertise the project-ideally, state officials say, with contract terms that will attract Coastal again as well as other bidders.

ABMB, a 100-employee firm that specializes in transportation engineering, has embraced the concept of continuous flow intersections.

The idea behind CFIs is to allow more cars to pass through intersections on green lights, thus cutting the amount of time stuck in traffic. They work by eliminating left-turn lanes at busy intersections-think anywhere along Airline Highway. Instead, left-turning drivers are diverted into a dedicated "bay" several hundred feet before the intersection, ultimately feeding them into cross traffic. All of this is controlled by a computer and a series of traffic lights (See graphic, page 14). A video demonstration can be found on ABMB's website (www.abmb.com).

Bruce says he was skeptical until relentless number-crunching and computer modeling-and driving the intersections in Tijuana and Juarez-changed his mind. The state hired his firm to model CFIs not just for the Siegen/Sherwood intersection but also for Goodwood, Old Hammond Highway and Bluebonnet Boulevard as a possible alternative to a $17 million widening project planned for Airline between Goodwood and Cedarcrest.

If the Siegen/Sherwood test project performs well-presuming it gets built-the state could forgo the widening project and build the remaining three CFIs. The four intersections together would cost between $10 million and $11 million to build, Bruce says. ABMB would get between 4% and 10% of the total construction cost as engineering fees.

Bruce, who's also working with the Mississippi highway department on designing a CFI for Natchez, admits the concept has been a tough sell. The fact that they're well-established in Mexico isn't necessarily a strong selling point in the United States.

"Skeptics are good," he says. "Traffic engineers and engineers in general, we're all conservative people and we don't like taking chances. We've been taught a certain a way to do things, and if it gets outside that of that we get kind of nervous."

Though they've been "researched to death," he says, CFIs are hardly used in the United States because state highway departments are afraid of being blamed for expensive flops based on untested ideas.

Another barrier is that despite its merits in combating traffic jams, the design effectively eliminates access to corner businesses. That makes CFIs unworkable at many urban intersections, and is why ABMB's plan for the Siegen/Sherwood pilot project includes frontage roads.

The CFI in Long Island was built by a local college at a lightly traveled, rural intersection, so it isn't much of a test case.

But Maryland took the plunge by installing one at a bona fide busy intersection on a crowded commuter route.

Kirk McClellan, director of the office of highway development for the Maryland State Highway Adminis-tration, says his agency OK'd the plan to avoid having to build a more expensive "flyover" interchange, which starts at around $15 million. Francisco Mier, one of the original designers of the CFI concept and now a partner with ABMB, lent a hand in designing the Maryland intersection.

McClellan says that, safety-wise, Maryland's CFI is a plum: A study of the intersection two years into its operation revealed zero accidents caused by its unfamiliar design.

The downside, he agrees, is that it wipes out corner access-not an issue in this case since the intersection is a rural area. Still, access issues are the reason they're not practical for every busy intersection, McClellan says, especially in a place like Maryland, where development is pervasive.

"For us there's property issues we'd rather not wrestle with," he says. "That's the only downside that we see. It's a very effective design. We're continuing to look at more opportunities to use them."

Brian Wolshon, LSU professor of civil engineering wonders whether CFIs, with their extra lanes and traffic signals, will confuse motorists. Still, he likes the idea and applauds ABMB for staking its fortunes on an exotic innovation and DOTD for its open-mindedness.

"Bottom line, I really think it's going to work," Wolshon says. "Nothing ventured, nothing gained, as the saying goes. Sooner or later people are going to try these."

Bruce, the true believer, is holding his breath until the shovels actually strike dirt on the pilot project. Even if CFIs don't make him rich, he says, the cachet of being a leader in practical innovation-doing it first and knowing it better than anyone-can only be good for business.

"It's helped us expose ourselves more nationally," he says. "It's different, and it gives us a niche market."

Steve Clark covers health care, higher education, environment and transportation.