Bus Braking Tests With and Without ABS

Although there is extensive information on the braking performance of automobiles, fewer studies have been done on deceleration values of heavy vehicles. This article reports on experimental tests that were carried out to evaluate the braking performance of an intercity bus. The braking characteristics and emergency braking performance of an intercity bus equipped with an antilock braking system (ABS) was compared with one without ABS. Experimental data were verified with dual instrumentation for the purpose of reducing the contribution of systematic uncertainties of the two measurement and data processing systems. Results showed that the braking performance of the bus with ABS was significantly better than when the ABS system was disabled. The case also demonstrates the level of uncertainty in calculating the initial velocity based on measurement of the skid marks left on the pavement.