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RESEARCH TRIANGLE LOGISTICS PARK TRAFFIC IMPACT ANALYSIS <br />Capacity Analysis <br />June 4, 2020 <br /> 23 <br /> <br />6.0 TRAFFIC ANALYSIS <br />Capacity analyses were performed for the roadway network in the project study area. The traffic analysis program <br />Synchro Version 10 was used to analyze all signalized and stop-controlled intersections according to methods put <br />forth by the Transportation Research Board’s Highway Capacity Manual (HCM)4. The Highway Capacity Manual <br />defines capacity as “the maximum rate of flow at which persons or vehicles can be reasonably expected to traverse a <br />point or uniform section of a lane or roadway during a specified time period under prevailing roadway, traffic, and <br />control conditions, usually expressed as vehicles per lane per hour.” <br />Level of service (LOS) is a term used to describe different traffic conditions and is defined as a “qualitative measure <br />describing operational conditions within a traffic stream, and their perception by motorists/ or passengers.” LOS <br />varies from Level A, representing free flow, to Level F where traffic breakdown conditions are evident. At an <br />unsignalized intersection, the primary traffic on the main roadway is virtually uninterrupted. Therefore, the overall <br />delay for the intersection is usually less than what is calculated for the minor street movements. The overall <br />intersection delay and the delay for the intersection’s minor movement(s) are reported in the summary tables of this <br />report. Generally, LOS D is acceptable for signalized intersections in suburban areas during peak periods. With the <br />current method of reporting LOS for unsignalized intersections, it is not uncommon for some of the minor street <br />movements to be operating at a LOS F during peak hour conditions and that is not necessarily indicative of an area <br />that requires improvements. <br />Capacity analyses were completed in accordance with NCDOT Congestion Management Capacity Analysis <br />Guidelines5 . It should be noted that the analyses includes permitted + protected signal phasing in-addition to right- <br />turn-on-red at the intersection of Old NC 86 at Waterstone Drive / Rippy Lane. This provided results more indicative <br />of field conditions as the signal currently operates with a flashing yellow arrow. Table 3 presents the criteria of each <br />LOS as indicated in the HCM 5. <br />Table 3: Level of Service Criteria <br />Level of Service <br />(LOS) <br />Signalized Intersection <br />Control Delay <br />(seconds / vehicle) <br />Unsignalized Intersection <br />Control Delay <br />(seconds / vehicle) <br />A ” ” <br />B !DQG” !DQG” <br />C !DQG” !DQG” <br />D !DQG” !DQG” <br />E !DQG” !DQG” <br />F >80 >50 <br /> <br /> <br />146