Recently I asked the City Council to authorize additional funding for more road maintenance in the form of reclaiming. The request was for approximately $150,000. This request was made because of the bad spring we had and the resulting damage to our roads. Reclaiming is one of several different methods of road maintenance we do in an effort to extend the life of our roads.
Road maintenance methods include reconstruction, reclaiming (new), milling and overlays, seal coating, and patching. The life of a road can be viewed in terms of these various maintenance types. All of these maintenance types have a specific purpose and take place at the appropriate point in the road’s life cycle.
Reconstruction is the process of tearing out the old road and building a brand new one. In the old days, the base built under a road was not good. In some cases, gravel was put right on top of slough bottom. When we rebuild a road today, we dig down deeper and put in a good gravel base. In some cases, we put down a fabric liner to protect the road from moisture. This base helps increase the life of the road through the ability to do a better job of maintenance.
Reclaiming is a new method of maintenance we added. This is done when the road can’t be fixed with any other maintenance methods. During the reclaiming process, we have a milling machine come in and mill the entire three inch blacktop surface. The milling process extends down into the gravel base and there is a mixing of the two material types. Once the milling is done, City crews then remove all the millings to a three inch depth. After the final packing and grading, we put back a new three inch blacktop surface. This is usually done in two separate one and one half inch steps or “lifts”. We let one lift set for a period time to check for settling of the base.
Milling and overlaying is the process taking off the top one and one-half inches of blacktop and putting on a new surface. This can’t be done if there isn’t a good base. A milling machine is used to remove this top layer. Imperfections in the road are corrected prior to the resurfacing process. We also can’t do a mill and overlay if the road is cracked up really bad. The cracks tend to reflect back through the surface during the freeze/thaw cycles over the winter. This past spring was particularly hard on the roads with lots of cracks.
Seal coating is probably the most questioned type of maintenance. I’ve been asked a number of times why we cover a perfectly good road with sand or gravel. The answer is we are putting a cover on the road. This new cover of oil and “pea rock” will now serve as the wear surface for the road. The cover wears out and not the blacktop surface underneath. The goal is to get about seven years out of this process. Then we would do another seal coat. Once we have done it twice, then we will probably do a mill and overlay if the base is good.
The last method is patching. This is very time consuming and depends or our ability to get patching material. In the winter and spring we use what is called a winter mix. In the late spring and summer we wait for the blacktop plant to open to get the summer mix. Right now we are waiting for enough patch mix to get caught up. The goal is to limit the amount of road patching and focus on the other methods of maintenance. During the recent long spring, the freeze thaw cycles were especially bad.