Not for the faint
Approach eliminates “black outs”
The city of El Paso, Texas, had a very costly problem. Because of the extreme summer heat, and its effect on asphalt pavements, their traffic markings were being “blacked out” by the heated rubber tires of the area’s commuters. Consequently, the city was forced to replace its thermoplastic road markings on major thoroughfares as frequently as every six months.
Twice a year, the existing thermoplastic lines would be removed by a grinding truck and replaced with new ones. Each time, the scarring of the asphalt by the grinding trucks would be a little deeper and a little more damaging to the pavement. Unfortunately, within a couple of months, the blacking-out process would begin showing up again on the newly applied lines. This remove-and-replace cycle appeared to be one the city was faced with indefinitely.
Chad Sargent, road-marking specialist for Stripe-A-Zone Inc. in Grand Prairie, Texas, had an idea on how to solve this reoccurring problem. He was very familiar with the issue, as it is his company that is currently contracted by the city for the remove-and-replace services. Equipped with his newly acquired Stripe Hog SH8000, Sargent approached the city maintenance officials and suggested that they consider rejuvenating the blacked-out lines with his SH8000 captive waterblasting system. On his own time and expense, he identified a test site and coordinated a time for the demonstration.
The selected markings were less than two months old. The first step was to take an initial retroreflectivity reading of the selected markings, which resulted in readings between 54 and 62 millicandelas (mcd). The minimum retroreflectivity generally required by the Texas Department of Transportation for new striping is 175 mcd. After a single pass by the Stripe Hog SH8000, a second reading was taken with values between 250 and 275 mcd without causing any damage to the marking or surrounding pavement.
In the words of Daryl Cole, street maintenance supervisor for the city of El Paso, “The idea of simply rejuvenating the lines with the waterblaster was new for us and I was concerned about what the reflectivity readings would be after the cleaning. The end result far exceeded our expectations. It was very fast, didn’t leave any damage and is very environmentally friendly. We are now working on a plan for regular rejuvenation of the thermoplastic markings on our main streets. This is going to save our city a lot of money and eliminate the damage caused on our roads by grinding away the existing stripes. [Sargent] and his guys are definitely to be commended for their creative thinking in the interest of the city of El Paso.”
The case for the road and bridge industry is clear. The useful life of properly laid thermoplastic, epoxy and tape road markings can be extended indefinitely by properly designed and correctly operated waterblasting equipment, and the savings for municipalities and state DOTs will be very significant.
Not only is this the case for roads and bridges, but for airports as well. The rejuvenation of runway centerlines is just as simple and effective and produces a cost savings. Airports around the globe waste time and money frequently repainting runway centerlines. A regular rejuvenation ensures the safety of the runway and reduces the airports’ costs.