AN ALTERNATIVE METHOD OF ESTIMATING SPACE-MEAN SPEED

Abstract

Average travelling speed usually applied in the traffic analysis as required in the fundamental traffic model. As one type of speed under the space-mean speed, most of the researchers have derived the equation to estimate the space-mean speed. There are a few factors that influence the speed changes along the segment. The fluctuate speed along the segment give an idea to average the spot mean speed from at least two points in order to estimate the space-mean speed. This paper explores an alternative method on how to convert the time-mean speed to space-mean speed that can represent the actual operating speed along segment using the average technique. A total of 18 data sets of time-mean speed and space-mean speed in six segments of uninterrupted two-lane single carriageway road were collected using automatic traffic counter and moving car observer, respectively. Two sets of automatic traffic counter were installed along the segment to record the spot speed and then converted to the time-mean speed, while the moving car observer were conducted concurrently to get the space-mean speed. The data sets were analysed using linear regression analysis. The results of summary of model show a strong relationship with coefficient of determination, R²=0.808, while ANOVA test results show the coefficient of constant and time-mean speed is not zero with p-value is less than 0.05 at confident level of 95%. The error obtained from this alternative equation are lesser than the established equation and it recommends that the alternative equation is acceptable.