10.1 SR 08-01-2022 - Laserfiche WebLink

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HIGHWAY 10 CORRIDOR STUDY - FINAL REPORT Roadway Capacity A volume to capacity analysis was completed for the Highway 10 corridor to identify the existing level of congestion. Congestion on an existing roadway system is judged to exist when the ratio of traffic volume to roadway capacity approaches or exceeds 1.0. The ratio of volume to capacity (V/C) provides a measure of congestion for a roadway that can help determine if roadway improvements, access management, or travel demand management strategies are necessary. As noted, the existing AADT on Highway 10 is about 34,000 vpd. The typical planning level capacity for a four -lane divided rural roadway is 35,000 to 38,000 vpd. Given the existing volume to capacity ratio (V/Q is ranges from 0.89 to 0.97, the Highway 10 corridor is approaching capacity. Intersection Capacity To determine the capacity of key intersections along Highway 10, a Level of Service (LOS) analysis was conducted. Traffic volumes for a typical weekday (i.e., Tuesday/Wednesday) during the summer months were utilized for the intersection capacity analysis. The LOS is defined by a letter grade (A through F), which is determined by the calculated delay and/or the density of the roadway. Intersections are quantified from LOS A through LOS F based on these factors, in accordance with the Highway Capacity Manual (HCM). Current local guidance indicates overall intersection LOS D operations or better are considered acceptable. The capacity analysis utilized VISSIM, a traffic microsimulation software. This software allows the creation of existing roadway and intersection geometries, and inputs traffic volumes and signal timing information to replicate the existing traffic conditions within the project area. VISSIM provides an average delay experienced by drivers at each intersection and approach. The average approach delay and intersection delay determines the LOS (see Table 3). Table 3. Level of Service Criteria A <_ 10 <_ 10 B > 10-20 > 10-15 C > 20-35 > 15-25 D > 35 - 55 > 25 - 35 The analysis was completed for both the a.m. and p.m. peak hours, which represent 7:00 to 8:00 during the a.m. and 4:15 to 5:15 during the p.m. A summary of the existing study intersection levels of services during the a.m. and p.m. peak hours are illustrated in Figurel3and Figurel4, respectively and detailed results are in AppendixB. In general, all study intersections currently operate at an overall LOS C or better during the peak hours. However, access from the cross -streets onto or across Highway 10 is challenging, with several side -street approaches operating at LOS E or worse. These findings are consistent with field observations conducted as part of this study, as well as from feedback with key agency partners. a GHW4�, ■ _ �RRIOOR��