Robles and janson used loop detectors to collect the

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Unformatted text preview: collected data and developed configuration they simulated the traffic flow at I 25/HOV corridor. Using the DYMOD they simulated lane-blocking accidents and estimated the accident delays. The study showed that the simulation of 11 incidents provide an advantage to plan alternative routes for accidents and reduce delay times. In addition, the authors concluded that DYMOD could be used for planning traffic during construction projects. Schonfeld and Chien [13] developed a model to find the optimal work zone lengths for two- lane highways. They explain that highway maintenance is very expensive and the delay costs of users can actually exceed the maintenance expenditures by highway agencies. If flow exceeds the capacity of the open lanes, the n queues start forming, which increases travel times and resulting user costs. Schonfeld and Chien also note that the increase in average travel time is also proportional to the length of the work zone. As a general rule, longer work zones cause longer user delays. The study also indicates that agencies have tried to develop guidelines for sizing zones but better guidelines must be created to effectively integrate agency and user goals. Benz, Fenno, and Voigt [14] analyzed the advantages of traffic modeling in reconstruction projects. They analyzed the I-45 Pierce Elevated reconstruction in Houston. At the start of construction project the alternatives are analyzed to finish the project at minimum time. They used macroscopic simulatio n model FREFLO, a component of the CORFLO simulation model to analyze the construction zone. The alternatives are analyzed for weekdays and weekends and the results are used to determine the liquidated damage costs to be placed on the contractor. During the construction project the data are collected for evaluating and identifying the bottlenecks in the traffic. The collected data showed that there was not much traffic delays and increase on the travel time of the customers. The identification of the routes and phases in 12 the construction project before the construction started helped to prevent bottlenecks and delays. 2.2 Work Zone Simulation Program Results Evaluation Studies Rao and Owen [15] proposed a multistage validation procedure for the high- fidelity traffic simulation models. The multistage validation procedure is consisted of two approaches; conceptual validation and operational validation. In conceptual validation, model survey and model walkthrough methods are applied to the model. The operational validation is divided into two stages. The first one is qualitative approach, in which performance measures are compared graphically and by animation. The second approach is the quantitative approach. The first test in quantitative approach is comparing two means; the second test is the non-parametric approach in which Kolmogorov-Smirnov test, two dimensional two sample test, and one sample t-test are applied; the third test is the parametric approach, in which error analysis using autoregressive- integrated-movingaverage (ARIMA) is performed. The proposed analysis approach provides higher confidence level in the validation of simulation models. Rouphail and Tiwari [16] state that estimating capacity and level of service (LOS) at freeway construction zones is essential for the planning and scheduling of work zone traffic control. They conclude that traffic speed through a lane closure depends on the following features. Geometric features such as lane configuration, grades, curves, lane width, lateral clearance, sight distance, and proximity to ramps. Traffic features such as flow rates and (heavy) truck occurrence. Traffic control features such as signing, arrow 13 boards, and flaggermen. Work activity features such as location, crew size, equipment type noise, dust, and length of work zone. Carr [17] presents a model for predicting the Construction Congestion Cost (CO3 ) associated with work zones. He states that three types of delays can be present at work zones. The first one is the speed delays, which is the difference in time to travel through the work zone before and after the construction. The second one is the backup delays, which is the time that vehicles must wait to enter the work zo ne because of the reduced capacity within the area. The work zone delay is the sum of these two delay types. And the last one is the diversion delay, which is the difference in time to travel another path around the work zone. The presented model by Carr calculates these different kinds of delays, which can be observed at work zones. Carter, Rakha, and Van Aerde [18] analyzed the differences in traffic flow measures between freeway lanes. The main cause of the variability between the lanes is the requirement for passing to the left lane for faster vehicles and slower vehicles stay on the right lane. Another source of this variability is the presence of trucks. And the third factor causing the variability in the traffic flow between the lanes is the...
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