University of Twente Student Theses


Network Effects of Target Group Prioritisation by iTLC's

Hal, T.A.J. van (2021) Network Effects of Target Group Prioritisation by iTLC's.

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Abstract:This study assesses the effects of target group prioritisation on a network with multiple intersections controlled by intelligent traffic light control systems (iTLC’s). When target group prioritisation is applied, a specific group gets (or keeps) a green light and can cross therefore (almost) unhindered the intersection. Current studies on target group prioritisation focus on the effects on a single intersection, but little knowledge is yet available on the effects of this measure when applying it on a specific route, corridor or city area. Since policy choices on implementing this measure are not limited to a single intersection and it is expected that target group prioritisation will influence the traffic distribution and flows in the network, it is important that policy makers can make well-founded decisions based on the effects of target group prioritisation on network level. Therefore, this study assesses the effects of target group prioritisation by granting priority to freight traffic on a route with 7 TLC-controlled intersections, using an already existing macroscopic dynamic transport model of the Voorne-Putten region. To implement target group prioritisation in the macroscopic model, a trade-off is made between the different possibilities, which resulted in extending the green time for one direction on the chosen route. This does bring a limitation, since all the traffic on the route is prioritised instead of only one target group. However, the research still provide insight on the effects on all traffic, when one target group is prioritised. The effects of target group prioritisation are assessed for two different prioritisation scenarios. For the first scenario, the green times are extended with 30%, which should be feasible and realistic according to previous research. For the second scenario, the green times are extended with 60%, to see what the effects are in a more extreme case. For the assessment, both the travel time and number of vehicle kilometres are used as key performance indicators, to indicate if prioritised traffic benefits from the measure and if a shift in traffic distribution occurs. The KPI’s are used to assess the route as a whole, the route in parts and for two non-prioritised routes (side streets). In this way, it can be assessed if the desired beneficial effects occurs, and if not where on the route possible bottlenecks occur, and in addition the impact on non-prioritised traffic can be analysed. The analysis shows that applying target group prioritisation does not automatically result in travel time benefit for the prioritised direction as expected. Under normal traffic conditions (little/no congestion in the reference situation), the extension of green time results in a reduction of the travel time. However, an increase of traffic intensities resulted in bottlenecks on the prioritised route, mainly caused by the increase of turn delays for non-prioritised directions. Since for several junctions in the network the demand for a non-prioritised direction is high and capacity of this direction is reduced as a result of target group prioritisation, congestion and a blocking back effect occurs on the route. In addition, the increase in travel time for non-prioritised traffic resulted in a shift of the traffic distribution, including a decrease of traffic on the prioritised route. This indicates that for many origin-destination pairs (OD-pairs) in the network, for which one of the route alternatives drives partly over the prioritised route, the travel time benefit does not outweigh the increase in turn delay when entering/exiting the route. Therefore, the traffic of these routes choose an alternative, competitive route. However, the route part analysis showed that some parts of the route are more attractive as a result of target group prioritisation. This research shows that target group prioritisation does result in a shift of the traffic distribution and that it can be both beneficial or detrimental for prioritised and non-prioritised traffic, depending on the traffic conditions of the network. However, for a well-founded policy choice, more research on the network effects is needed. The results of this research only shows the effects of target group prioritisation on all traffic and does not distinguish between the different target groups. Besides, an extensive analysis on the traffic flows of the network is essential to identify a suitable trajectory to apply target group prioritisation on, so at least the prioritised target group does not experience detrimental effects.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Programme:Civil Engineering BSc (56952)
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