PD-17-00001 Marian Meadows Full Record with Index (2)

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Marian Meadows Rezone and Subdivision Final Environmental Impact Statement 3-91 Westbound approach vehicles experience increased delays as a result of higher through-movement volumes at the I-90 westbound ramps/Railroad Street intersection. At the Sparks Road/Railroad Street intersection, both the eastbound and westbound approaches (Sparks Road) are stop-controlled while Railroad Street is a free movement. The high-volume (478 vph) westbound left movement is the primary cause of delays. At Pit Way, high delays are associated with the northbound left movements (67 vph) that are unable to find adequate gaps in the traffic stream due to relatively high through-movement volumes. 24 Would the cumulative effects change collision frequencies and/or hazardous roadway conditions? Increased traffic volumes inherently increase the collision potential and existing hazardous roadway conditions can become exacerbated. Because the recent collision history indicates that traffic safety is not a concern (approximately 0.66 collisions/year compared to a 5.0 collisions/year guiding criterion), it is difficult to conclude if traffic safety is expected to be problematic in the future. All of the intersections in the study area are one-way/two-way stop-controlled. At these types of unsignalized intersections, the most common collisions occur between vehicles turning into and out of the minor approach with vehicles traveling through the intersection (versus rear-end collisions, sideswipes, or head-on). Conflicts between these vehicles generally arise as the result of aggressive driver behavior due to long minor street delays. Because the LOS of one-way/two-way stop-controlled intersections is defined by the minor street, a loose correlation can be drawn between the amount of minor street delay and collision potential. Although operating conditions may degrade beyond the LOS standards, five of the study intersections are not expected to experience excessive delays and the increases in traffic volumes associated with the cumulative effects are not expected to increase the collision potential to a level of concern. At the I-90 eastbound ramps/Railroad Street intersection, the eastbound left-turning movement would experience high delays, with a moderate level of traffic volume (275 vph). This eastbound left movement conflicts with three other movements that have moderate volumes, including the southbound left (188 vph), southbound through (185 vph), and northbound through (287 vph). Based on the high minor street delays and moderate traffic volumes of several conflicting movements, this intersection could experience a collision frequency at a level of concern. Additionally, the type of likely collisions (at- angle) could result in severe injuries. At the Sparks Road/Railroad Street intersection, which is expected to operate at LOS F, the collision potential would increase; however, approximately 96 percent of the total traffic entering the intersection reflect non-conflicting movements (781 northbound right turns and 478 westbound left turns). Therefore, while the collision potential at the Sparks Road/Railroad Street intersection would increase, it is not likely that the increase would be substantial.