| Operating a road network involves periodical reevaluations for the Level of Service and for safety indicators. Two-lane, two-way highways require more analyzing effort because of the passing issue. The vehicles are sharing their lane with oncoming passing vehicles. A lack of sufficient gaps, needed for the passing maneuver, can cause platoon forming, low speeds, time losing and low safety levels. Nowadays, the traffic engineers can use modern tools for simulations and reduce the cost of the analyzing process. Two-lane highways traffic simulations use models that reflect road geometry, traffic flow, sight distance profile, vehicle performances and drivers characteristics. However, some of these factors vary depending the country or region of the road studied. In Quebec, the highway design is regulated trough the "Normes de conception routieres" standard and for example, the heavy vehicles performance curves provided are different from the ones used by most of the simulation models. A different social, economic or cultural environment may also influence the vehicle types used and driver characteristics. Furthermore, most of the road geometry data in Quebec is available only in the form of GPS coordinates collected on the center line of the road. Other necessary data, like sight distances or superelevations, are not available and have to be calculated (or approximated). Existing algorithms and methods can help solving these matters.;Given these issues, a software tool was developed; the main purposes are: processing the input data for the simulations, running the simulations and preparing the simulation outputs for analysis. The tool follows Guillaume's (2006) method for detecting and studying passing problems on the two-lane, two-way highways.;;The software uses the TWOPASii model, which was selected from several options. TWOPAS was modified for compatibility with the Quebec standards regarding heavy vehicles performances and types. An adjustment was also made to allow simulation for road sections longer than 10 km. The input data processing modules are assigned the following tasks: reconstituting the road geometry from the GPS coordinates measured on the center line of the road; reconstitution results validation; sight distance calculation; providing an approximation of the horizontal curves superelevation. The reconstitution algorithm is a modified version of the one proposed by Vouland (2005). The superelevation calculation uses the 5th method from AASHTO (2004) and the equations developed by Baass (2005). The sight distance is calculated using an original solution.;Another software module manages the simulation---which requires multiple runs for stabilizing the results. Random numbers, demanded by TWOPAS (for generating speeds, gaps and vehicle entering order) are provided by the same module. To the software was added a user interface to ensure an easy data manipulation---especially for input files import and simulation output file export.;Several tests were performed in order to calibrate the algorithms used (using a fictive road) and to evaluate the effects of input errors on the simulation results (real road tests). Software reliability and efficiency were proved through these tests.;iiTWOPAS---microscopic model for two-lane, two-way traffic simulation developed by Midwest Research Institute in 1978 and improved several times. Last revision was made in 2004 when it was included in a modern interface. |
PDF Full Text Request