Traffic flow rate estimation is very important in the planning and design process for all aspects of the road network. Flow rates are most commonly estimated using a ‘stationary count’ that requires specialised equipment and is expensive to set up. In the 1950’s a method utilising a moving observer was suggested. Basically, it involves an observer in a moving vehicle counting the number of oncoming vehicles passed in a specified length of road. If the average speed of the moving vehicle, length of road and trip time is known, then the flow rate can be calculated. This study investigated the feasibility and accuracy of using this method for rural roads in New Zealand, many of which have low flow rates. A risk analysis approach was used to simulate moving observer surveys on roads with low flow rates. Results show that this method does not give accurate flow estimates for roads with a balanced two-way flow rate less than about 1000 vehicle per hour, unless one undertakes an impracticably large number of moving observer runs. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E213852.
Abstract