December 18, 2015

Wayne State traffic expert offers 8-point plan for safe, smooth holiday driving

Joseph Hummer, Wayne State College of Engineering

Some modest planning and a few simple driving techniques can help you do better with this year’s holiday traffic, says Professor Joseph Hummer, chair of Wayne State University’s Civil and Environmental Engineering Department in the College of Engineering. Hummer is a national expert on designing safe traffic flows, and he uses his experience to keep his own holiday driving smooth.

Here’s his eight-point plan for safe, smooth holiday driving:

1.) Make right turns. Left turns are surprisingly dangerous and lead to what traffic engineers call “conflict points.” Conflict points often lead to crashes; at the very least, conflict points often slow or stop traffic. Never make a left turn. Especially never make a left turn out onto a busy street. Coming out of a shopping center, make a right turn and either circle the block or look for a place to make a U-turn. You’ll minimize your delay and cut your chances of a crash by orders of magnitude.

2.) Find the back entrances. Back entrances often feed onto less-busy streets that offer easier travel than main arteries. Don’t feel the need to use the front door even if that’s what your GPS says. Think ahead a little bit, look at a map, know the area well enough that you know the back ways. Almost all of the centers do have a back way in or out, and a lot of them are surprisingly underused.

3.) Know how to skip the freeway. Often a boulevard surface street like Detroit’s 8 Mile Road offers an easier drive than a traffic-choked freeway. Those big freeway interchanges were built in the 1960s, but they were designed in the 1950s, and those folks were hoping that interchange would last until the year 2000. They never anticipated that same interchange would still be in business in 2016. If you must go through those places, know your alternate routes and don’t be afraid to use them.

4.) Avoid the five-lanes. Roads with two lanes of traffic on either side of a continuous left-turn center lane are a recipe for traffic conflicts and are typically overdeveloped with strip malls and mixed retail. Take alternate routes to get as close to your destination as possible. Those roads were never meant to handle those kinds of demands. The five-lane road is an unsafe and inefficient traffic cross-section; it leads to a lot of those conflict points.

5.) Seek out the mall. Traffic features adjacent to malls are generally well-engineered to handle massive vehicle flow, and malls themselves usually design their entrances, exits and on-property roadways well.

6.) Watch out for “spillback.” A malfunctioning signal, an accident at an intersection or simply too much traffic demand starts a queue of cars that builds backward. Soon it blocks nearby entrances and driveways and propagates a traffic jam that builds in every direction like an ice crystal forming. Many smartphone GPS and in-car navigation systems can give warnings of developing spillback. A pre-departure online check of a traffic map can help drivers avoid the red zones of traffic stoppage.

7.) Be weather-aware. The bad weather that happens this time of year is really the first round of weather that people aren’t used to driving in — snow, ice or even just a nasty rain. Of course, slow down and allow extra time, and be wary of other people who aren’t slowing down.

8.) Watch out for the other drivers. Holidays bring people with diverse driving habits into your area, and they may not be fluent with traffic designs such as the Michigan Left Turn or roundabouts. There is a little bit of extra traffic difficulty because of unfamiliar drivers out there, out of town drivers or people not accustomed to the area who may be visiting. A little patience can help a lot.

Hummer notes that sometimes traffic jams are simply unavoidable even with the best design. Most roadways are designed to handle peak commuting loads headed into and out of employment centers, so holiday retail traffic is not the traffic planner’s major focus. “For a traffic light, there’s still only 60 seconds in a minute,” he says. ”We have to allocate the seconds at a signal to meet the demands as fairly as we can, but sometimes a demand just overwhelms the number of seconds. There’s just not enough green time for everybody.”


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