Influence of pavement distress on capacity loss and their implications for PCE
The subject of this study is the extent of pavement distress impact on traffic capacity of uninterrupted road link sections. It aimed to ascertain whether road pavement distress would have significant influence on roadway capacity loss. Pavement distress is a persistence problem in Nigeria and indeed many developing countries - it is reflected in terms of increase in the followings among others: increase in travel time, and road user costs. Potholing, edge subsidence and pavement cracking under tropical climate are problematic in developing countries. Even though governments in Nigeria have spent huge sums of money to dampen the effects of poor pavement conditions, the progress made so far is painfully small. The objectives were to measure roadway capacity in the presence of pavement distress and compare with that taken without the influence pavement distress. To that effect a pavement distress impact study was carried out at 12 selected sites in Nigeria for a period of six months under daylight and dry weather conditions. Based on the circumstances prevalent at the time of survey in Nigeria the study assumed that density was a resultant of speed and flow hence not directly affected by pavement distress. This implies that roadway capacity loss was fully the result of speed changes. Vehicle types, volumes and speeds were collected at each surveyed road section and the results analysed. Capacities of the road section were estimated for three sections ('without distress', 'transition' and 'with distress') of the road link and it was found that capacities on 'without distress and 'with distress' sections differed significantly. After achieving the aim of the study, the roadway capacity loss was related to pavement distress using polynomial modelling and multiple regression techniques. Results confirm that pavement distress has relationship with roadway capacity loss and the study concludes that a significant decrease in capacity of about 30% was found and is attributable to road pavement distress.