You can set your watch by it. Every weekday around 3 p.m., when the dayshifts let out at Kawasaki Motors and St. Francis Hospital, the traffic along South Main Street turns into a royal pain in the neck for an hour or so.
Among the worst bottlenecks along the heavily travelled thoroughfare — if not the worst bottleneck — is the stoplight-controlled intersection at Main and South Avenue.
According to City Manager Greg McDanel, it's a complex intersection, and it creates the kind of complex traffic-flow problems that are going to take a lot of time and money to solve.
McDanel said redesigning the corridor for optimum traffic flow would include things like realigning — and at times eliminating — the myriad of curb-cut entryways into retail businesses that line both sides of the street.
Other changes would likely include reconfigured lanes, new traffic signals and improved pedestrian features that, taken altogether, could cost between $8 million and $10 million. Engineering alone for a comprehensive set of South Main solutions could total more than $750,000, McDanel said.
Suffice to say that while such a project is not out of the question at some point, it's probably not going to happen anytime soon. So McDanel and his bosses on the Maryville City Council have begun looking at an interim, and more affordable, solution.
The council began a discussion this week on a proposal to equip the Main/South Avenue junction with radar-driven traffic detection technology that McDanel said could save motorists, on average, between seven and 20 seconds when passing through the intersection from each of its four points of entry.
That may not sound like a lot, but 10 or 15 seconds per car multiplied by hundreds of cars could significantly ease congestion along South Main as well as frustration for drivers trying to cross the artery from the east or west using South Avenue.
Radar detection would replace the current "puck" system, which consists of hockey puck-sized sensors embedded into the pavement.
The sensors detect vehicles as they approach the intersection and emit electronic signals that cause the lights to change.
Though an improvement over low-tech signal timers, the pucks have issues of their own. For one thing they activate the left-turn signal if even a single vehicle rolls into the turn lane rather than waiting for several cars to queue up.
Another issue is that the puck-controlled signals operate in basically the same timing sequence regardless of the time of day, whether traffic is congested or not.
Finally, the pucks are powered with batteries, and when the batteries run down the street has to be blocked off while the pucks are removed and the power cells replaced.
Radar solves a lot of these issues, McDanel said, by creating extended 90-degree profiles of the entire intersection that include both turning lanes and through traffic. In addition, the system can be programmed to "learn" traffic patterns over time and adjust itself accordingly.
Page 2 of 2 - As for cost, McDanel said purchasing and installing a radar-based system would run about $26,000, not exactly chump change but a long way from $10 million.
Acquiring the system this year would require taking the money out of reserves, but it would also allow for installation of the new technology this summer as Main continues to do double duty as a detour for Munn Avenue, which is closed for reconstruction.
McDanel made no direct recommendation to the council with regard to going with radar-controlled stoplights, but he did note that congestion along South Main is apt to increase as retail and residential development continues.
"Although the improvement does not completely alleviate the problem, staff believes congestion would be reduced," he said.