This is the first of two papers on the simulation of traffic on the A9 autobahn in Germany. It covers the data acquisition and calibration of the FREQ computer model, whose 11th version was used. The second paper will cover the model's applications to traffic management investigations. The model predicts traffic performance measures for each subsection along the corridor facility in every time slice. Then traffic performance measures are aggregated over time for each subsection and for the whole facility, for each time slice, and for the whole study period. The model includes a menu-driven interactive interface with comprehensive input checking and various output options. It can be used to study a wide variety of traffic control strategies, such as the effect of traffic demand changes, maintenance and construction, optimised ramp metering, and many integrated improvement schemes. The data include supply side and demand side input and field-measured traffic performance data. The stages of the calibration process are: (1) using the initial input; (2) modifications of subsection capacities; (3) modifications of speed-flow relationships; and (4) additional calibrations. The paper emphasises the need for high-quality performance data, and a multi-stage iterative calibration process.
Samenvatting