Improving the method of forecasting traffic design volume


Project abstract:

This project aimed to improve the method of measuring the traffic design volume for new construction projects: The old approach – based on the analysis of past data collected via automated traffic counters – was adapted into an approach which can reflect changes in future transport demand (forecasting ability), e.g. due to demographic change, and thus improves the profitability of planned infrastructure (out-of-town roads). In order to do so, the variables influencing the structure, purpose, amount, and temporal distribution of passenger transport were analysed. Possible scenarios for one forecasting year were derived from the results. Individual hydrographs were calculated for each stretch of road in the model networks using dynamic route assignment. Using statistical methods, standardized hydrographs for stretches of roads were determined on the basis of the criteria type of road, load (cars, trucks), function within the network, spatial category etc. to process the large statistical population. The hydrographs were then assigned duration curves. The results were presented practically and adhering to the guidelines as an addition to the 2001 HBS. In doing so, assignment rules were provided so that the hydrograph, duration curve, and the traffic design volume can be derived from the load forecast for a stretch of road.

Working plan:

The research project was divided into the following steps:

WP 1 Sample survey road authorities:

  • Conducting a survey of the road authorities of the federal states regarding the practice of measuring the traffic design volume

WP 2 Variables influencing the amount and structure of road passenger transport:

  • Evaluating research on possible development scenarios
  • Causes of the temporal and purpose-specific distribution of the traffic volume
  • Spatial-structural influences etc.
  • Providing a data basis for the simulation

WP 3 Forecasting the temporal distribution of the transport demand (hydrograph) based on the model calculations:

  • Deciding on the conditions for one forecasting year.
  • Nationwide demand calculation for road transport for an analysis situation and the forecasting year
  • Dynamic road assignment of traffic for both reference situations and calculation of load values per hour for each stretch of road of the model networks.

WP 4 Determining the impact of forecast hydrographs on duration curves:

  • Determining standardized hydrographs based on the criteria:
    • Type of road, load (cars, trucks), function within the network, spatial category etc. using statistical methods.
  • Assigning duration curves to the hydrograph types by projecting the frequency of types of day (work days, days during holiday seasons, holidays etc.).

WP 5 Developing a procedure to derive forecasted traffic design volumes:

  • Practical presentation of the results of the study as an addition to the 2001 HBS
  • Assigning hydrographs, duration curves and traffic design volume to types of roads at a given load (ADT)

WP 6 Reports:

  • Detailing the methods, meetings with the client

Project duration:

January 2006 – July 2008

Project partners:

PTV Planung Transport Verkehr AG

Bauhaus Universität Weimar, Professur für Verkehrsplanung und Verkehrstechnik, Univ.-Prof. Dr.-Ing. Brannolte

Contact at the ISB:

Dipl.-Ing. Katja Johänning