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Desktop RSA Activity

Desktop RSA Activity. 4-52. Desktop RSA Activity. Follow the RSA Process:. Step 1: Identify project or existing road to be reviewed. Step 2: Select an independent, multi-disciplinary RSA team. 4-53. Desktop RSA Activity. Step 3: Conduct a start-up meeting.

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Desktop RSA Activity

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  1. Desktop RSA Activity 4-52

  2. Desktop RSA Activity Follow the RSA Process: Step 1: Identify project or existing road to be reviewed. Step 2: Select an independent, multi-disciplinary RSA team. 4-53

  3. Desktop RSA Activity Step 3: Conduct a start-up meeting. The Virginia Ave. and Ward St. intersection is the meeting of two busy roadways in an urban residential area. 4-54

  4. Desktop RSA Activity Step 3: Conduct a start-up meeting. In the last three years, there have been 47 crashes with a 17% fatality rate. 4-55

  5. Desktop RSA Activity The intersection experiences a variety of environmental conditions including some winter icing. Step 3: Conduct a start-up meeting. 4-56

  6. Desktop RSA Activity Getting Started • Learn about your teammates to appreciate multi-disciplinary potential. • Agree on spokesman, and secretary. • Begin analyzing materials. 4-57

  7. Desktop RSA Activity Present Findings • Use PowerPoint or flip chart. • Select a single team member to make presentation. • Use FHWA internet resources. 4-58

  8. Virginia Ave. and Ward St. - 1 • Virginia Ave. and Ward St. are both minor arterials. • All approaches have speed limits of 25 mph. • A substantial proportion of drivers exceed the speed limit on Virginia Ave. by about 10 mph. A long straight alignment and infrequent signals along Virginia Ave. may encourage drivers to speed. • Left turns are prohibited only on westbound Virginia Ave. (turning south onto Ward St.). • The intersection geometry is skewed and offset. 4-59

  9. Virginia Ave. and Ward St. - 2 • Stop bars and pedestrian crosswalks are quite worn. No stop bar or crosswalk is provided on the east leg. • The absence of a crosswalk on the east leg may be due to the perceived need to align it with the southeast corner of the intersection, which would position it about 85 feet from the northeast corner of the intersection. The resulting intersection configuration would be confusing for westbound drivers, and would require an unusually long signal clearance interval. 4-60

  10. Ward St. - Looking North • The northbound Ward Street approach splits close to the intersection: drivers turning right continue straight ahead, and drivers turning left or continuing north on Ward Street follow a curved alignment to the left. • The intersection is in a residential area, with private homes on all corners. • Laning on the northbound and southbound legs is marked with overhead lane-use signs (yellow box). 4-61

  11. Ward St.- Looking North • Closer view from previous angle • Pavement markings supplement overhead lane use signs for the left turn lane • Through drivers on Ward St. must steer an S-shaped path through the intersection. No guiding lines are provided in the intersection. Drivers turning left from Ward St. must be aware of these paths steered by adjacent and opposing through vehicles to avoid interfering with them. 4-62

  12. Ward St. - Looking South • Overhead lane use signs are supplemented with pavement markings for the left turn lane. 4-63

  13. Virginia Ave. - Looking West - 1 • Virginia Ave. has one wide marked approach lane in each direction. Drivers typically use the single wide approach lane as two lanes, both on the midblock approaches to the intersection and at the intersection itself. • The curb-to-curb width is about 42 feet. Using the single wide approach lanes as two lanes creates an effective lane width of about 10.5 feet (depending on the location of the painted centerline). Lanes of this width are considered acceptable on low-speed roads in a constrained environment. 4-64

  14. Virginia Ave.- Looking West - 2 • Parking is prohibited near the intersection. • Left turns are prohibited on this approach. • No stop bar or pedestrian crosswalk is provided over this approach. 4-65

  15. Virginia Ave. - Looking East • The approach lanes are wide. • Left turns are permitted from this approach. • No stop bar or pedestrian crosswalk is provided over this approach. 4-66

  16. Traffic Control - 1 • A raised concrete island at the intersection divides the northbound Ward St. approach. • Traffic turning right passes to the right of the island and is controlled by a STOP sign. • Through and left-turn traffic passes to the left of the island and is controlled by a signal. • Four signal heads are suspended from diagonal span wires over the intersection, such that two signals are displayed for each direction as shown in the slide. 4-67

  17. Traffic Control - 2 • The signal is pre-timed with two phases: all east/west movements followed by all north/south movements. • The diagonal span wires place the signal heads directly over or behind drivers who have advanced into the intersection to turn left. These drivers cannot see the signal when they are waiting in the intersection to turn. As a result, left-turning drivers sometimes remain in the intersection past the amber and all-red signal phases. 4-68

  18. Signal Display • All signal lenses are eight inches (200 millimetres) in diameter. • Pedestrian signal heads are present on the north leg only. • The signal has a 55- to 65-second cycle length, depending on the time of day. • Clearance intervals are: amber phases of 4.0 seconds (all approaches) followed by all-red phases of 2.5 seconds (east and west approaches) and 2.0 seconds (north and south approaches). 4-69

  19. Afternoon Peak Hour Traffic Volumes - 1 • The afternoon traffic counts show substantial southbound left turns onto Virginia Ave. and westbound right turns onto Ward St. • Small turning volumes were observed on the eastbound left turn onto Ward St., and the northbound right turn onto Virginia Ave. 4-70

  20. Afternoon Peak Hour Traffic Volumes - 1 • Pedestrian signal heads are present on the north leg only. • The signal has a 55- to 65-second cycle length, depending on the time of day. • Clearance intervals are: amber phases of 4.0 seconds (all approaches) followed by all-red phases of 2.5 seconds (east and west approaches) and 2.0 seconds (north and south approaches). 4-71

  21. Crash History • Over the three years for which crash data was available, 47 collisions were recorded at or near the intersection of Virginia Ave. and Ward St., of which 17 percent resulted in at least one non-fatal injury. 4-72

  22. Crash History • The collision diagram indicates the following trends: • A cluster of sideswipe collisions on the eastbound Virginia Ave. approach may result from drivers’ frequent use of the single wide lane as two lanes, especially to bypass a vehicle waiting to turn left. Sideswipe collisions may occur when one driver is unaware of another driver’s intention to pass. 4-73

  23. Crash History • A cluster of rear-end and sideswipe collisions on the southbound Ward St. approach appears to reflect drivers’ confusion regarding the appropriate path to steer once they have entered this large, skewed, offset intersection. • Southbound drivers turning left are at particular risk, since they must avoid interfering with adjacent through traffic, opposing through traffic, and opposing left-turn traffic. 4-74

  24. Collision Distribution: Type • Sideswipe, rear-end, and left-turn head-on collisions dominate statistically, though no collision types are over-represented relative to the regional proportions for signalized intersections of this size. 4-75

  25. Collision Distribution: Month • A chart of temporal trends shows varying monthly peaks. 4-76

  26. Collision Distribution: Hour • The hourly collision distribution reflects a typical afternoon commuter volume peak. However, no corresponding collision peak occurs during the morning commuter peak. 4-77

  27. Collision Distribution: Road Surface • The proportions reflected in these environmental collision trends reflect typical weather and road conditions throughout the year. 4-78

  28. Collision Distribution: Lighting Conditions • These proportions may simply reflect exposure -- in other words, about three-quarters of traffic volume occurs during daylight hours. 4-79

  29. Safety Issues - 1 4-80

  30. Safety Issues - 2 4-81

  31. Suggested Mitigation 4-82

  32. Suggested Mitigation 4-83

  33. Desktop RSA Activity Present Findings • Encourage positive discussion with project owner. • Alter mitigation suggestions as necessary. 4-84

  34. Day 2 Preparations and Wrap-up Day 2 Practice RSA plans include: • Transportation • Materials • Safety precautions • Comfortable clothing • Cameras • Road user assignments Questions about Day 1? 4-85

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