Improving a model for speed density relationship on arterial roads in Baghdad City

Abstract EN

This paper was undertaken to investigate the relationships between speed and density on urban arterial roads of Baghdad City.

This research work was based on the traffic survey data (PC volume and average speed) collected in Palestine Street in 3 sections at two directions through 12 hours within 3 weekdays.

The density is computed using fundamental formula of traffic flow.

Eight theoretical Speed-Density models (5 are single Regime Models and 3 are Multi-Regime models) are validated by the field data by two statistical test methods (CHISQ test and Paired T-test).

The results show that no one of the theoretical models is good in fit with the real data.

Then a Multi-Regime Model is improved under two ranges of density (<70 and >70) at south approach and (<60 and >60) at north appraoch .

This model is tested using regression analysis, CHISQ test, and Paired T-test.

This analysis shows that the model has good fit with the field data.