4.10. SR 01-20-2015 - Laserfiche WebLink

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Spack Consulting 3 of 6 1715` Ave & Twin Lakes Rd Traffic Analysis Alternatives Evaluation With three alternatives developed, several measures of effectiveness were developed for comparison purposes. Each measure is described briefly below: Level of Service — Using the methodology presented in the Highway Capacity Manual, intersections are assigned a "Level of Service" letter grade for the peak hour of traffic based on the number of lanes at the intersection, traffic volumes, traffic control, and other characteristics. Level of Service A (LOS A) represents light traffic flow (free flow conditions) while Level of Service F (LOS F) represents heavy traffic flow (over capacity conditions). Generally, a LOS D is considered acceptable by most public agencies. Individual movements are also assigned LOS grades. For this memorandum, the p.m. peak hour was analyzed since it has the highest overall traffic volumes. Vehicle Stacking — Along with LOS results, the Highway Capacity Manual methodology can calculate the number of vehicles that will stack, or queue, while waiting to proceed through an intersection. Shorter queues are generally consistent with shorter delays and less congestion. As with the Level of Service, the vehicle stacking measure of effectiveness was based upon the p.m. peak hour with the highest overall traffic volumes. Ability to Accommodate Over -sized Trucks — Given the industrial nature of the surrounding area and conversations that occurred when the roundabout alternative was presented, any alternative must be able to satisfactorily accommodate over -sized semi - trucks. In this case, accommodation generally refers to limiting roadway curves, providing wide intersection radii, and the ability to provide wide travel lanes. Safety — Safety can be measured in many different ways. For the purposes of this memorandum, safety refers to the potential for vehicle conflicts, and thus crashes, at the intersection or surrounding corridor. For instance, a four -lane corridor has a greater potential for conflicts due to the potential for sideswipes on the corridor and more vehicle conflict points at an intersection. Right -of -Way Needs — Sufficient Right -of -Way has already been reserved for a four -lane section and a roundabout for the new intersection if that is the chosen configuration. Therefore, this evaluation refers to the ability to return some Right -of -Way to the surrounding private property owners if not needed. Future Flexibility — The Scenario 2 traffic volumes are projections of what may occur in the future based on many assumptions. A change in one or more assumptions that went into the projections could alter those traffic volumes. This measure of effectiveness therefore refers to the ability to accommodate geometric changes if the traffic volumes are different than expected. Cost — Although detailed cost estimates were not developed for each alternative, the relative cost between alternatives can be compared for this measure of effectiveness. Table 1 presents the results of the alternative comparison based upon the measures of effectiveness discussed above. Each alternative was compared against the others for the purposes of this summary table and given a ranking of one to five. A ranking of one represents the best option for a particular measure while a ranking of five represents the worst option. Ties, or the same ranking, were given to alternatives with relatively similar results.