2 comparison of arena with quickzone in the arena

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Unformatted text preview: e two lanes were simulated separately. Outputs of the ARENA simulation model were obtained both for driving lane and passing lane. The ARENA simulation model provided the desired outputs, such as queue length, transfer time, and waiting time. The animation feature of the ARENA simulation program was used. Animation showed that traffic and merging behavior reflect real world conditions observed in the field. 117 In the outputs of the ARENA simulation program, it was observed that the number of vehicles generated as a function of time of the day is very close to the actual observed data. Therefore the IAT distributions developed appears to be correct. The developed ARENA simulation model could not be fully evaluated over a wide range of traffic volumes since the actual traffic volumes which were observed and collected at I-76 Westbound were not high enough to cause queues in the lane reduction area. In their study, Maze and Kamyab [2] state that traffic volumes less than 700 vehicles/hour (total for both lanes) do not result in any queues at the taper. It is expected that the ARENA simulation model developed for the I-76 westbound construction work zone example will be very useful for future construction zone modeling efforts. 118 5 CONCLUSIONS In this study, a simulation model for a construction work zone where the number of lanes was reduced was developed using the ARENA simulation program. The cars and the trucks in this model were represented by entity – transporter pairs. However, the model has a number of limitations and therefore does not represent the lane reduction situation (especially the acceleration and deceleration dynamics) accurately. The vehicles on the driving lane do not decelerate when there is a queue formed at the lane closure taper. The simulation run time of the model in its present form also takes a considerable time since the time compression factor is about 1:62, in other words 62 real time seconds are simulated in 1 second. It roughly takes 30 minutes on a PC with 2.8 GHz processor to simulate 24 hours of 2 lane car and truck traffic. Unfortunately, the lane reduction traffic situation for which the data was collected in the real world does not appear to produce queues or delay times, thus the developed model has not been tested when considerable queues or delay times due to lane closures are present. No queues were observed during the data collection over the three day period, therefore the model output appears to be correct for traffic situations and traffic volumes observed. Similar non-queue observations were stated by Maze and Kamyab [2] for traffic volumes of 700 vehicles/hour (for both lanes) or less. 119 In order to validate the ARENA simulation model, further analysis where there are 2 lane traffic situations with a lane reduction to one lane and higher traffic volumes resulting in queues at the taper will need to be studied in the future. In addition, the model needs to be refined to include an algorithm for decreasing the speeds of the vehicles in the driving lane when there are vehicles waiting at the lane closure taper. The continuous modeling option in the ARENA simulation program can also be explored and, if possible, included in the model. The use of the templates option rather than extensive and repetitive groups of if statements could be explored and if possible included in the model. Further work will be required to model construction work zone situations where there are entrance and exit ramps in the construction work zone. The model will need to be refined to be more adaptable for different construction work zones with different sign locations indicating that there is a lane reduction ahead. The model could be extended to include the percentages of vehicles and speeds of the vehicles varying according to the time of the day. The model could be made more user friendly so that a minimum preparation work is required to run a particular simulation. 120 6 [1] REFERENCES Balci, Osman, Guidelines for Successful Simulation Studies, Proceedings of the 1990 Winter Simulation Conference, 1990, pp. 25-32. [2] Maze, Tom and Kamyab, Ali, Work Zone Simulation Model: Companion Report for Traffic Measurement Strategies for Merge Areas i Rural Interstate Work n Zones, Center for Transportation Research and Education Management Project 97-12, September 1999. [3] Gross, Donald and Harris, Carl M., Fundamentals of Queueing Theory, John Wiley & Sons, Inc., Second Edition, 1985, pp. 13-35. [4] QuickZone, Turner-Fairbank Highway Research Center, http://www.tfhrc.gov/its/quickzon.htm, accessed on 10/12/2004. [5] A l-Kaisy, A., Stewart, J.A., and Van Aerde, M., Simulation Approach for Examining Capacity and Operational Performance at Freeway Diverge Areas, Canadian Journal of Civil Engineering, Vol.26, No.6, December 1999, pp.760770. [6] Benekohal, Rahim F. and Abu-Lebdeh, Ghassan, Variability Analysis of Traffic Simulation Outputs: Practical Approach for TRAF-NETSIM, Transportation Research Record, No.1457, 1994, pp.198-207. [7] Bloomberg,...
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