Highway Research Record

VI. RESEARCH WORK DONE IN ACADEMIC INSTITUTIONS RELATED TO THESIS WORK
A. HIGHWAY PLANNING, MANAGEMENT, PERFORMANCE EVALUATION AND INSTRUMENTATION
A Study on Effect of Pavement Unevenness on Capacity of Two-Lane Roads

Date of Start:January 2005
National Institute of Technology, Tiruchirappalli (R, S)

Scope and Objective
One of the major unknown aspects in capacity studies is the effect of pavement condition or the surface unevenness on operating speed. The aim of the present study is to identify the effect of roughness on the free speed of a vehicle and the capacity of two lane road.
(i) To identify the effect of road roughness on the free speed of the vehicles.
(ii) To identify the effect of roughness on Passenger Car Unit.
(iii) To identify the effect of roughness on Capacity of a Two-Lane road.

Methodology
(i) Taking roughness measurements on selected road stretches by using British Towed fifth wheel bump integrator.
(ii) Measuring the Free Flow Speed of the vehicles by using Radar Gun at every 100 m interval of a km to find the average      speed for the entire km.
(iii) Collection of speed–flow data at minimum 8 locations of two-lane highways.
(iv) Analysis of data to establish the relationships between roughness and free speed of different vehicles.

Findings and Conclusions
(i) The present study has shown that the Free Flow Speed of a vehicle decreases with the roughness of the road surface.     The effect of roughness is more apparent on the speed of passenger cars than of heavy vehicles.
(ii) The PCU for a vehicle type decreases linearly with roughness. Non motorized vehicles are not influenced much by road      roughness while the speed of motorized vehicles is greatly influenced.
(iii) The speed–volume relationships drawn at different sections of two-lane road indicate that the capacity decreases with an       increase in the road roughness.