04-15-2020 PC - Laserfiche WebLink

Home Browse Search

February 28, 2020 Page 5 K:\014908-000\Traffic\Traffic Study\Lake Valentine Road Study.docx ANALYSIS PROCESS The purpose of this analysis is to determine the existing and build year traffic operations for the roadway network within the vicinity of the proposed development. The following summarizes the study process and evaluation results. Analysis Tool Synchro/SimTraffic analysis software was used to analyze the Build Condition scenarios. Synchro10 is a traffic operations analysis software package that implements the methodologies of the Highway Capacity Manual (HCM). Data from Synchro10 is transferred to SimTraffic10, a detailed microscopic model that considers vehicle driver behavior, detailed interaction of vehicles with each other and the roadway between adjacent intersections, random behavior of drivers, and the delay for individual vehicles throughout the peak hour. Synchro10 uses the HCM methodology to analyze intersection operations through one cycle of a traffic signal while SimTraffic10 simulates the operation of the network of traffic signals through multiple cycles over a specif ied period of time (e.g., 60 minutes). Intersection Level of Service The ability of an intersection to process traffic is affected by the number and type of vehicles, desired turning movements, intersection geometrics, and traffic control devices. Inters ection level of service (LOS) differs from segment LOS in that the quality of traffic operations is defined as the delay to vehicles caused by the intersection’s traffic control rather than the ratio of vehicle volumes to roadway capacity. Intersection LOS typically focuses on operations during the periods of the day with the highest traffic volumes whereas segment LOS is based on traffic volumes over an average 24-hour period. Thus, the intersection LOS analysis gives a “worst-case” result for each intersection and more clearly identifies operational problems at the intersections. Because traffic signal timing is optimized in order to provide the best overall intersection delay, while still keeping minor movement delay tolerable, movements with very low volumes may experience higher delays than some high volume movements. In a coord inated system, priority is given to the largest volume movements (usually through movements), and when a traffic signal has a long cycle length, the majority of green time is allotted to the high volume movements. Because of this, lower volume movements may experience LOS E or F simply because of the long duration between green phases provided that movement. For example, if the northbound movement during the PM peak hour is the primary movement, a small volume of southbound left turning vehicles may suffer prolonged delay even with a very short average queue. The intersection operational analysis process includes determining the LOS for the key intersections under the existing peak hour traffic conditions. The City of Arden Hills has identified that if a roadway operates at a Level of Service C or better during peak hours, it is generally considered acceptable. If a roadway operates with a LOS D or worse during peak hours, improvements should be considered (City of Arden Hills 2040 Comprehensive Plan). Figure 3 presents the intersection LOS thresholds, in terms of seconds of vehicle delay, as defined in the HCM.