University of Twente Student Theses


Vehicle classification in traffic models

Vink, J.J. (2020) Vehicle classification in traffic models.

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Abstract:For traffic simulation it is necessary to know a lot of parameters. One of these is the vehicle classification. In order to be able to model a certain situation the composition of the traffic needs to be known to create a well-functioning model. There are a lot of different types and sizes of vehicles on the road, which makes it necessary for traffic simulation software to distinguish different vehicle types. The first step for determining the correct vehicle type is by collecting the data in the first place. In the Netherlands there is a public database for traffic on most national roads, the NDW. The data that is shared by them is already classified in three or five different classifications. Whether it is three or five categories depends on the accuracy of the measurement with higher accuracy measurements being represented by the five classifications system. For urban roads the NDW does not provide that much information, but this problem is sorted by companies like Sweco performing the needed traffic measurements themselves. Sweco also uses a classification system, but that has 13 vehicle classifications. To get the optimal representation of reality by a model it is ideal that individual vehicle data is available so that the traffic simulation software can have a tailor-made vehicle classification. Most of the vehicles are easy to determine a fitting vehicle category for in traffic simulation software. However, especially vans are a problematic vehicle category, because of the fact that they fall somewhat in between passenger cars and trucks, which are the most common vehicle categories in traffic simulation software. To determine the influence of the vehicle classification on the capacity of a road network some simulations are run. Because urban traffic is much different from highway traffic both of these two situations are considered. The highway situation is represented by an on-ramp on a highway and the urban situation by a signalled intersection. Three of the most used traffic simulation programs used by Sweco are used to determine the effect of vehicle classification on the capacity. Fosim and Vissim are used for the highway situation and Vissim and Paramics are used for the urban situation. Not only is there looked at the maximum capacity of these situations for multiple factors of freight traffic, but also the passenger car equivalent values for the capacity is considered. All the results show a linear correlation in the decrease of the capacity when there is an increase in the freight traffic factor. For the highways this is a decrease of around 70 vehicles per hour per percent and for the urban situation this is only around 5 vehicles per hour per percent less. The PCE-values for the highways also show a slight decrease in capacity, but only by around 20 vehicles per hour per percent less. However, the PCE-values for the capacity of the urban situation show an increase in capacity for additional freight traffic with an increase of around 3 vehicles per hour per percent freight traffic. If the PCE-values would remain the same for each freight traffic factor it does not matter in which category vans are placed. However, because this is not the case there are slight changes in capacity possible for classifying vans in a different category. These changes are up to two percent for highways and up to three percent for the urban situation when it is known that vans make up almost seven percent of all Dutch vehicles.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Programme:Civil Engineering BSc (56952)
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