A Few Good Counting Stations

Many cities use traffic counting stations. These stations sometimes do more than just count volumes – they can be used to measure vehicle speeds as well. Some large jurisdictions use these traffic monitoring stations to get congestion information, and use this data as part of a Traveller Information System. Calgary uses traffic monitoring stations as well, but at this time has only three monitoring stations that can measure both speed and volume. Calgary also has an Advanced Traveller Information System, and would like to be able to provide congestion information through it. This paper collects and analyses data from some of Calgary’s traffic monitoring stations, in order to determine what information can be provided by the stations to a Traveller Information System, with a focus on providing congestion information. Many days worth of data has been collected and analysed in order to assess trends and find useful information. The research done for this paper indicates that the best indication of congestion is the mean speed of traffic passing a monitoring station. As congestion grows, the mean speed will decrease. Several causes of congestion (peak period, weather and incident related) were analysed and all show a decrease in mean speed. Additionally, the standard deviation of the speed can also be used as an indicator of the reason for congestion, since accidents often cause a different distribution of speeds compared to a typical peak period.