Essential Maintenance: Asphalt Pavement Lots
By: Adam McManus
According to the University of Michigan Transportation Research Group, there were 10,000 vehicles in the United States in 1901, and 100 million by 1968. In 1970, singer/songwriter Joni Mitchell wrote and recorded a Big Yellow Taxi with the famous and appropriate lyrics, “They paved paradise and put up a parking lot.” With the 4th largest vehicle per capita ratio in the world, there are a tremendous amount of parking lots in this country. Estimates indicate as many as 2 billion parking spaces nationwide. Parking resources are also as varied as they are vast. Some lots, such as stadium, arena or other event parking are sporadically filled to capacity while the spaces for commuter parking or large commercial or retail areas are occupied daily. Some lots, like a shopping mall have a high volume of turnover and pedestrian traffic, while others such as a aPark & Ridea facilities may not.
Well designed and well constructed parking will be able to handle the traffic flow, provide pedestrian security, and properly drain water. A well managed parking lot will be maintained and serviced to handle user wear and tear and weather factors. Quality composition that is properly maintained is key to extending the lifespan of any parking facility.
Weather factors including: ultra violet light, freeze thaw cycles, and heavy precipitation are typical factors that negatively impact asphalt. Frequent snow and ice accumulation are common to the Northeast winters. Snow plows and deicing salts need to be used to ensure surfaces remain usable; however, they inevitably create distressed areas in the asphalt pavement.
There is a progression of degradation in the pavement that stems from a combination of weather and traffic. As the asphalt surface wears, it becomes discolored or faded. Cracks typically form, exposing the aggregate below the surface. As the asphalt becomes more distressed, severe alligator cracks, pot holes, ruts from vehicle tires and undulations in the pavement can form.
Cracks in the asphalt pavement allow moisture and chemicals, such as oil and gasoline from vehicles, to enter the pavement system. Oil leaks can break down the asphalt cement in the pavement. Seal coating and back-filling of cracks to mitigate the intrusion of unwanted chemicals and water, should be part of an annual maintenance program. Depending on the volume of use and the grade of asphalt, parking lots should be resealed every 1 to 3 years. Preparation, including the treatment of oil spots, is key to the proper application of a seal coat.
Parking lot maintenance should also include any necessary curb repairs and intrusive root system control. Additionally, paint striping will maintain the aesthetic quality of the lot.
If asphalt topping becomes extensively deteriorated, a thin overlay, or a cold mill and pave option, will address the top few inches of the material.
In the past decade, photovoltaic panels have become an option for aunderutilized real estatea such as parking lots. Rutgers University has the largest parking canopy installation in the United States. The canopy units protect the asphalt pavement, as well as the vehicles, from direct sunlight and other detrimental weather conditions.