Development of traffic micro-simulation model for motorway merges with ramp metering
Al-Obaedi, J 2011, Development of traffic micro-simulation model for motorway merges with ramp metering , PhD thesis, Salford : University of Salford.
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This thesis focuses on the development of a micro-simulation model for motorway merge sections. The aim is to study the effectiveness of applying some traffic management controls and particularly focuses on applying ramp metering (RM) systems. The new model has been developed based on car-following, lane changing and gap acceptance rules. The model considered the multi-decisions undertaken by merging traffic when a driver, for example, accepts the lead gap and rejects the lag gap. The cooperative nature of drivers is also considered where motorway drivers allow others to merge in front of them either by decelerating or shifting to other lanes (yielding) in the vicinity of motorway merge sections. Video recordings, as well as data from the Motorway Incident Detection and Automatic Signalling (MIDAS) were obtained from a selection of sites. The data was used in the verification, calibration and validation processes of the developed model. Other main sources of information include more than 4 million cases of successive vehicles taken from UK motorway sites. These cases were analysed to study the effect of vehicle types on the following behaviour for drivers. The main finding is that there is no evidence that the average spacing between successive vehicles is significantly affected by the type of leading vehicle. Different RM algorithms have been integrated within the developed model. The results of testing the effectiveness of RM controls using the developed model reveal the benefits of RM in reducing time spent by motorway traffic (TTSM) but it significantly increases the time spent by the merging traffic (TTSM). The overall benefits of implementing RM in reducing total time spent (TTS) is limited to situations where the sum of motorway and merge flows exceeds the capacity of the downstream section. Other issues related to RM design and effectiveness have been tested such as the effects of having different durations for peak periods, finding the optimum parameters for each algorithm, the effect of ramp length (storage area) and the effect of RM signals position. The results suggest that RM is very efficient when implemented for short peak periods (e.g. less than 30 minutes). The effectiveness of RM in decreasing the travel time for motorway traffic is increased with an increasing ramp length but with a significant increase in ramp traffic delay. No significant effect is obtained from altering the ramp signals' position. Other tests include the use of other types of traffic management controls (e.g. applying different speed limits and lane changing restrictions (LCR) at the approach to merge sections). No significant improvements were obtained from testing different speed limit values. The results suggest that LCR could reduce travel time for motorway traffic. However, there are other practical considerations which need to be addressed before this could be recommended.
|Item Type:||Thesis (PhD)|
|Schools:||Colleges and Schools > College of Science & Technology|
Colleges and Schools > College of Science & Technology > School of Computing, Science and Engineering
|Depositing User:||Institutional Repository|
|Date Deposited:||03 Oct 2012 14:34|
|Last Modified:||20 Aug 2013 18:32|
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