Driving lane speed 35 fts no yes lag gap in driving

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Unformatted text preview: /s >= Driving Lane Speed > 55 ft/s NO NO 55 ft/s >= Driving Lane Speed > 35 ft/s NO NO 35 ft/s >= Driving Lane Speed > 10 ft/s NO NO Lag Gap in Driving Lane >= 75 ft Hold until finding available Gap YES NO Lag Gap in Driving Lane >= 155 ft YES NO YES NO Lag Gap in Driving Lane >= 120 ft YES NO YES NO YES 55 ft/s >= Driving Lane Speed > 35 ft/s NO YES Lag Gap in Driving Lane >= 90 ft 75 ft/s >= Driving Lane Speed > 55 ft/s NO YES Lag Gap in Driving Lane >= 110 ft Driving Lane Speed > 75 ft/s YES 35 ft/s >= Driving Lane Speed > 10 ft/s NO NO Lead Gap in Driving Lane >= 30 ft YES Lead Gap in Driving Lane >= 110 ft YES YES Lead Gap in Driving Lane >= 75 ft YES YES Lead Gap in Driving Lane >= 65 ft YES YES Lead Gap in Driving Lane >= 45 ft YES YES Merge to Next Station on Driving Lane Figure 23: Flowchart of the ARENA Traffic Simulation Model (continued) If more than 10 entities with transporters are waiting at the taper, check for the speeds and when the specified gap is available in the driving lane, merge to the driving lane; else wait in the queue until finding available gap for lane changing. 89 DRIVING LANE Assumptions Truck PASSING LANE Car First Station After the Left Lane Closure Taper Transport to the Last Station, 800 ft after the Lane Closure Taper Free Transporters Car First Station After the Left Lane Closure Taper Transport to the Last Station, 800 ft after the Lane Closure Taper Truck Free Transporters Record Entity Statistics Dispose Entities Record Entity Statistics Dispose Entities Figure 23: Flowchart of the ARENA Traffic Simulation Model (continued) Explanations: After the lane closure taper ends all entities on the driving lanes shift to the shoulder, and continue in the onelane section of the construction zone Entities arrive to the last location in the simulation Entity statistics are recorded and entities are disposed. 90 3.2.2.3 Output Variables In this study as it was stated in the objectives, delay times and the queue lengths were investigated. This information is the most important outputs of the ARENA simulation model. The simulation run length was assigned as 24 hours. The model was run for 72 replications in order to get independent and random outputs for the simulation. 900 seconds of warm- up period was also specified in the simulation run parameters. Statistics for each entity was recorded into a text file by the model. Entity number, entity type (passing lane car, passing lane truck, driving lane car, driving lane car), entity create time, wait time, total times were recorded. In addition, the queue length at the taper and the waiting time at the passing lane closure taper were recorded as the output of the system. 3.2.2.4 Limitations During the development of the simulation model, some limitations of the ARENA simulation program were observed. In the ARENA simulation program, some limitations with respect to transporters were observed. After the guided vehicle transporters are freed, released by the entity, they remain at the location where they are freed. When there are many numbers of transporters in the system, the user of the program has to assign greater distances for the locations where the transporters are released. Another limitation observed with respect to transporters was, not being able to specify acceleration and deceleration rates explicitly 91 for the transporters. Initially variable speed cannot be assigned to the transporters in the program. Velocity of the transporters can be assigned with a probabilistic distribution only after the transporters are requested and active. In the design of the model, intersections and links were used for simulating road. Intersections were paired with the stations defined in the model. Events occur at the intersections and the vehicle characteristics such as lane changing behavior can only be incorporated at these intersections. In this traffic simulation model in some cases, intersections which are 50 feet apart were created in order to allow the integration of vehicle characteristics in a continuous manner to the system. Some of the entity output variables were created with the statistics model in order to use the ARENA output analyzer function for the analysis. The output analyzer did not function with the model, resulting in an error that the model size is too big even when it was a research version. 3.3 Description and Design of QuickZone Delay Estimation Progra m The QuickZone work zone delay estimation program was developed by The Federal Highway Administration (FHWA) in cooperation with Mitretek Systems [4]. It uses a deterministic queueing model to simulate traffic going through work zones to determine when there would be traffic backups. It is a tool intended for highway engineers to determine how to set up a work zone to minimize traffic disruption [27]. MD-QuickZone Version 1.01 was used for the simulation of the same construction work zone used in the ARENA simulation model. MD-QuickZone Version 92 1.01 was developed by University of Maryland [29] starting from a regional QuickZone developed by the FHWA. 3.3.1 Inputs of QuickZone...
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This document was uploaded on 02/26/2014 for the course E 515 at University of Louisiana at Lafayette.

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