SCSC2003 Abstract S953
COMPARISON OF INTEGRATION AND NETSIM NON-STEADY STATE CAR-FOLLOWING BEHAVIOR
COMPARISON OF INTEGRATION AND NETSIM NON-STEADY STATE CAR-FOLLOWING BEHAVIOR
Submitting Author: Dr. Hesham Rakha
Abstract:
The paper compares the NETSIM and INTEGRATION car-following models applied to non-steady state conditions.
Analytical solutions are derived in order to provide a reference for comparison. The paper not only demonstrates
differences between the models, but also explains why differences in model results may occur. In both over-saturated and under-saturated deterministic, arterial environments, the models are consistent in estimates of delay and travel time. Alternatively, the models are inconsistent in estimates of vehicle stops, stopped delay, fuel consumption, and emissions. Specifically, the NETSIM model underestimates the number of vehicle stops in comparison with the analytical formulation. Likewise, the estimates of vehicle stops in the INTEGRATION model are slightly lower than the analytical formulation. The NETSIM vehicle speed and acceleration profiles can be characterized by more abrupt accelerations
than observed in INTEGRATION. This not only contributed to differences in estimates of stopped delay, but was also a
significant factor in causing differences in fuel consumption and emission estimates.
In under-saturated and over-saturated random arrivals, it was observed that the INTEGRATION model is consistent with
the analytical solution over the full range of volume-to-capacity ratios. The NETSIM model was observed to under
estimate delays, in comparison with the analytical formulation. The under-estimation was particularly evident for v/c ratios ranging from 0.9 to 1.2, where the random delay is significant. Finally, it is observed that minor differences exist between CORSIM version 4.32 and CORSIM version 5.0 in terms of estimates of the measures of effectiveness.
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