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Terry Stawar

The closure of the Sherman Minton Bridge earlier this month sent us all scrambling for alternative routes. I quickly discovered that only about 10,000 other motorists knew my secret shortcut, down Corydon Ridge Road, along the hairpin twists and turns, through Brown’s Station Way, to Jeffersonville.

I have been influenced by my father, who was a firm believer in shortcuts. Most of his, however involved litter strewn alleyways, roads with standing water, and death-defying excursions through the most dangerous parts of town, all of which terrified my mother.

In Florida, I worked for a man who had formerly driven a delivery truck in Tampa. He knew every short cut in town, as well as every place you could get a decent Cuban sandwich. When he would drive to meetings, it frequently took longer to get there, but the fried plantains always made up for it. On the rare occasion when we would get totally lost, he referred to it as a “frolicking detour.”

The most enthusiastic users of short cuts are known as rat runners. Rat-running is mostly using secondary streets, instead of main roads, to avoid traffic delays. Although it may have something to do with “the rat race,” no one is sure where the name originated. In the 1960s, behavioral psychologists, who studied rats, were nicknamed “rat-runners,” and rodent maze behavior is often compared to how humans act in traffic.

 Besides using residential side streets that parallel main routes, other rat-running techniques include driving through parking lots to avoid traffic lights and exiting main roads to dodge traffic jams. Rat-runners like to keep their shortcuts secret. I wouldn’t have mentioned mine, if I thought it could possibly get any worse.

Many of these practices are controversial and even illegal. Homeowners complain that rat-running disturbs the peace, makes their neighborhoods unsafe and decreases property values. However, enforcing laws against rat-running is very difficult, and many communities have tried to employ other methods to prevent it.

These so-called “traffic-calming” measures include installing four-way stops, speed bumps, rumble strips, curb extensions, cobblestones and traffic circles. Some of the newer residential developments have purposely included long winding roads and multiple dead-ends to discourage these practices. Other cities have designated certain streets as one-way and have limited access to through traffic during rush hours.

I have noticed an increased police presence on many alternative routes that run through residential areas, which I believe has served to slow down some of the traffic which poses a special threat to children and bicyclists.

While taking my favorite shortcut to church last Sunday on the newly opened Daisy Lane, I suddenly found myself on of all things — a roundabout. “Roundabout is the British term for a road junction in which traffic travels in one direction around a central island replacing the traditional intersection.

A 1998 survey found that about 68 percent of Americans opposed roundabouts. At church, I heard grumbling about the one at Daisy Lane.

When I got on this demented merry-go-round with no prior warning, I had no idea what to do. My greatest fear was making a mistake and causing a crash. My wife Diane, imagines herself caught in a spinning top, is afraid that she’ll be thrown off in the wrong direction.

The 1998 survey also reported that after people become familiar with roundabout 73 percent favor them. Of course, things could be worse. Carmel has the dubious distinction of having more than 75 roundabouts and even hosted a national roundabout conference this year.

According to the May 2000 Status Report from the Insurance Institute for Highway Study, roundabouts are safer than intersections and reduce vehicle collisions by about 40 percent. Reportedly, they have 80 percent fewer injuries and 90 percent fewer fatalities.

I have to hand it to the city of Bartlesville, Okla., which in early September sent all of its residents, enclosed in their utility bills, a pamphlet on how to use roundabouts, just before the city opened its first roundabout. You can still download “A Citizen’s Guide to Modern Roundabouts” from the city website at http://tinyurl.com/TrafficRA. (Important hint: entering traffic must always yield)

While we all want to take the shortest route possible, research conducted by Hyejin Youn and Hawoong Jeong, of the Korea Advanced Institute of Science and Technology, and Michael Gastner, of the Santa Fe Institute, indicated that selfish shortcuts can do more harm than good by actually slowing traffic down. They concluded that when everyone tries to use the shortest route, this jams up the entire network.

For example, if there are two different routes to a single destination, and one route is a bit shorter, the average driving time is less for everyone if half the drivers take one route and half take the other. But instead of that happening, many drivers will quickly switch over to the shorter route.

However, as traffic flow increases on the shorter route, the longer one starts to look attractive, so some drivers will switch back. Traffic flow between the two routes eventually reaches what is called a Nash equilibrium, named after mathematician John Nash (from Ron Howard’s movie “A Beautiful Mind”). At this point, both routes are relatively slow and neither holds any advantage. Average driving time is much higher than it would have been if drivers had split equally between the two routes.

For routes with many different links, researchers were able to calculate what they called the “price of anarchy,” which is the slowness introduced to the network by drivers all seeking the best route. In Boston, for example, this resulted in an average route that took 30 percent longer than the optimal route. In London, it resulted in a 24 percent increase in wasted time, and in New York 28 percent.

At this point, you might think that maybe authorities should just add more network capacity (additional roads or bridges). Mathematician Dietrich Braess discovered that adding extra capacity — when drivers choose their own best routes — can in some cases paradoxically reduce overall network efficiency. This is true because the Nash equilibrium of a system usually is not optimal. In the worst case scenario, actual driving time may be twice as long as the optimal driving time.

The phenomena of increased network capacity decreasing efficiency is called Braess’ Paradox. It has about a 50 percent chance of occurring whenever a new route is added. In certain situations, the inverse can also be true, that is by closing down some routes, traffic flow can actually be improved.

Better traffic flow due to route closures has been reported in South Korea, Germany, New York and most recently in Los Angeles, when Freeway 405 shut down. So, theoretically, one way to reduce everyone’s average drive time is simply to limit drivers’ options by closing key roads or routes.

In Boston, for example, there were 246 streets in the main traffic route. For 240 of these streets, closing any one of them created even more severe traffic jams. However, for the remaining six streets, closing any one of them actually reduced drivers’ average travel time. Similar results were also seen in London and New York.     

I suppose the odds that closing the Sherman Minton Bridge will actually improve traffic flow is pretty slim. However, if I go down Daisy Lane again, at least I won’t be contributing to the traffic problems on the Kennedy Bridge, because I’ll be stuck in that dang circle. Round and round she goes, where she lands nobody knows.

— Terry L. Stawar, Ed.D., lives in Georgetown and is the CEO of LifeSpring the local community mental health center in Jeffersonville. He can be reached at tstawar@lifespr.com. Checkout his Welcome to Planet-Terry blog and podcast at www.planetterry.wordpress.com.