Performance of Low Volume Sealed Road Pavements: a Case Study of Roads 2000 Strategy in Central Kenya

Abstract

The road sector in Kenya is an integral part of its economy. The country has approximately 170,000 kilometres of road network, managed by the line ministry, through the Kenya Roads Board (KRB), Road Authorities and other Agencies. Insufficient financial resources, organizational and operational systems with inadequate investment in maintenance has led to the devaluation of the road network as an asset, as well as the aftermath effects of high vehicle operating costs which directly affects the economy negatively. The deplorable condition of these road assets led the Government of Kenya to shift its emphasis from the construction of new roads to the rehabilitation and maintenance of the existing road network using the maintenance strategy known as the Roads 2000 (R2000) Strategy. The strategy aimed to improve road maintenance and construction by introducing appropriate technology on a road network basis for the selective rehabilitation, spot improvement and maintenance of prioritised links. The strategic goal of the R2000 program was to bring the rural road network of Class D, E and Special Purpose roads including parts of the unclassified network to a maintainable standard and ensure that KRB Road Maintenance Levy Fund (RMLF) resources are used to maintain the maintainable and recently improved road network. This study aimed at evaluating the performance of the low volume pavements on completed roads, and assessing the impacts of the R2000 program in Central Kenya. Roads constructed under the three batches of phase two were investigated to establish the current condition of the roads. The present serviceability was assessed by taking and analysing roughness and rutting measurements, and in addition to visual assessments, a present serviceability rating was assigned. The level of investment by the authorities on maintenance was evaluated by analysing the prioritisation criteria towards fund allocation. Axle control by the authorities on the completed roads was examined by conducting axle loading and analysis of the present traffic loading. Further, the roads were assessed for climate resilience using visual methods, and whether the appropriate adaptation techniques are in place to improve the climate resilience of the infrastructure. All the data from these investigations were collected and analysed using the appropriate methods, standards and tools, and the results used to make valid conclusion on the performance of the completed low volume sealed roads. The major defects on the road were noted and examined closely to determine the extent and cause of the defect. Such defects included rut development, pothole formation, delamination of pavement layers, longitudinal, transverse and crocodile cracking, encroachment of vegetation onto the carriageway and stone loss. Each road had its own specific dominating defects, arising from.........................................