Traffic: An increase in the total volume of traffic that serves a road segment regardless of the type of road. It can be measured in terms of the number of vehicles or the magnitude of the travel distance. Traffic growth is typically accompanied by an increase in daily traffic volume that causes deterioration of the pavement surface. A reduction in daily traffic volume or a change in the type of traffic can cause a decline in pavement conditions. Traffic load is one of the most important variables that affects pavement condition. Traffic load directly affects the pavement surface through direct vehicle loads and indirectly through the traffic vibrations transmitted to the pavement surface. These vibrations cause distortion of the pavement surface, acceleration of surface cracking and further deterioration in the stability of the pavement structure.
Traffic vibration: Vibration transmitted to the pavement surface from the tires of vehicles traveling over the road and the vibration transmitted from the road surface to the vehicle through the suspension system. Pavement structure, traffic, traffic load and pavement surface conditions are factors that affect traffic vibration. Traffic vibration is often an important factor in roadway distress. Traffic vibration may cause or accelerate surface distress and accelerate cracking of the pavement structure. Both single vehicle disturbances and multi-vehicle disturbances are referred to as traffic vibration. Single vehicle traffic disturbance can be described as any vibration produced by a vehicle traveling at a relatively low speed. Multi-vehicle traffic disturbance is defined as any vibration produced by a vehicle traveling at a high speed over a short distance or traveling at a relatively low speed over a long distance. Traffic vibration can be distinguished as a low frequency disturbance or a high frequency disturbance.
Rutting - is the formation of a large crack-like pattern within the pavement surface. These cracks develop with time and are caused by the expansion and contraction of pavement under traffic loads. They are typically deeper than the crack depth and can extend through the pavement thickness. The spacing of the ruts indicates the direction of movement of the traffic load .  reported the use of GPR to detect rutting within flexible pavements.
Stripping - is the loss of the bituminous film (i.e. asphalt) from the top of the pavement surface. It typically occurs at visible discontinuities in the pavement such as “joints,” “crossovers,” and “sills” . It is a precursor to structural cracking and is caused by differential temperatures causing stress and cracking under the bituminous film . A recent GPR study used GPR to improve pavement stripping detection .
Historically, the types of sensors utilized have generally been limited to what is easily deployed, portable, or affordable. Currently, digital cameras, digital video cameras, and laser scanners are the most common sensors used for pavement analysis. Thermal or infrared cameras can be used to detect the temperature of pavement and detect distress, such as cracks and cold inclusions. 827ec27edc