Ask Autoblog: How are Michigan roads made?
The process of constructing roadways in a Michigan is a long and arduous one that takes many millions of dollars, countless workers standing around and at least five seasons to finish. Roadways here on the home turf of the American auto industry are a unique breed. Even though Windsor, Ontario is just across the river from Detroit and has exactly the same climatic conditions, its roads are completely different from those in Michigan. That becomes immediately apparent as your roll off the Ambassador Bridge. We here at Autoblog strive to keep you, our loyal readers, informed about all things even vaguely related to cars. Therefore, we present our step-by-step guide to the creation of a Michigan road.
The process typically starts in the spring as soon as the salt has been rinsed away. Before the first crocuses pop out of the dirt, the crews start setting out signs and orange barrels along the edges of the most heavily traveled thoroughfares. There they typically sit for anywhere from one to four weeks before the crews return to start closing off lanes of traffic. After another interval of random length, the heavy equipment begins to arrive and the process of tearing apart the existing pavement begins. Just to make sure that no one accidentally misses out on the fun, the same scenario is usually repeated along several parallel paths that might serve as alternate routes between any two major points that people commute.
Learn about the rest of the process after the jump.
Creative commons - Flickr - Ricarr
Throughout the spring and summer and often well into the fall, construction crews will shut down lanes of traffic often for several miles while they tear up old pavement, crush it and lay down new pavement. Interstates passing through Michigan are typically paved with concrete rather than asphalt, which is then finished in a special texture that seems calculated to excite certain harmonic frequencies in car tires at any speed over 30 mph. This is done to ensure that drivers never forget they are driving on Michigan roads.
After labor day rolls around and the kids head back to school, the completion of summer road trips means that the need to restrict traffic is lessened. As the leaves start to change colors, the crews wrap up the first phase of their construction projects. At this point, most states are finished, but Michigan is just getting started. With a fresh layer of pavement in place, the real work now begins. Fortunately, Michigan is one of only a few states that still allows 80 ton trucks on its major roadways, which helps accomplish the second stage.
On the concrete highways, the extra weight aids the development of cracks, which are necessary for subsequent stages of the process. In the cities where the roads are paved with asphalt, the big trucks generate waves in the pavement as they come to a stop at intersections. These waves alert inattentive drivers that they are approaching an intersection without the need to look up from their McGriddle or makeup bag.
As the primary construction crews pack up and the winter snow and ice arrives, the inevitable cracks and gaps in the pavement do their part. Winters can get cold in Michigan, but they tend not stay that way for long. It's not at all unusual to have temperatures cycling between 10F and 40F several times within the same week. As the melted snow seeps into those cracks, re-freezes and expands, it can rupture even the toughest concrete and asphalt is no match. This allows large chunks of road to be easily removed before being later replaced with patches.
Late February and early March is the prime season for this phase of the process, although it can occur at anytime from Halloween to late April. Once the water has created the necessary cavities (perhaps we should start lacing our snow with fluoride?) the cold patch crews can go to work. In Michigan, this consists typically of three to four trucks, one of which is filled with cold asphalt patching material. These convoys trundle along the roadways, often blocking two lanes, as one or two out of the dozen-strong crew shovels the patching material into the craters. To be on the safe side, the patch material is piled several inches above the surrounding pavement.
Tamping down the patch is the responsibility of cars that drive by for the next hour or so. While this does save the repair crews from having to perform this extra step, it has the unfortunate side effect of spraying passing cars with asphalt, but that's a small price to pay to save the aching back of a state employee. One of the things that makes Michigan roadways truly unique in America is that the asphalt cold patch is used on both asphalt roads and concrete pavement. Since the patching material seems to adhere only sporadically to concrete, regular re-application is necessary.
At this point, the Michigan road is more or less complete, but like a good wine it does take some aging. Continued pounding by the big trucks and several more cycles of winter and patching yields the finished product. Meanwhile, the main construction crews start anew each spring with more sections of road.