Superstreet Concepts & Application. Prepared by: PAPE-DAWSON ENGINEERS, INC. October 16, 2012

Transcription

1 Superstreet Concepts & Application Prepared by: PAPE-DAWSON ENGINEERS, INC. October 16,

2 Purpose of a Superstreet Improve Traffic Flow Increased Safety Economical Solution

3 What is a Superstreet? Innovative intersection improvement Also referred to as a Restricted Crossing U-Turn Intersection (RCUT) Minor street traffic turn right Minor street left-turns and through required to U-turn downstream

4 Vehicle Movements

5 Pedestrian Movements

6 Safety Benefits Reduction in Conflict Points

7 Operational Benefits of Superstreets Per FHWA: Superstreets can provide up to a 30% increase in throughput (vehicles exiting intersection per hour) Superstreets can provide up to a 40% reduction in network travel time reductions

8 Capacity Benefits of Superstreets Loop 337, New Braunfles (Simulation Results)

9 Where Are They Deployed? Michigan - Median U-Turn (Michigan Left) intersections common; one RCUT intersection at Big Beaver Rd in Troy, MI Maryland Deployed primarily as a rural unsignalized safety treatment, called a J-Turn North Carolina: US 17 in Leland US 17 in Pender County SU at Erwin/Europa Drive, Chapel Hill US 1 near VASS, Moore County US 74 west of Waynesville, Haywood County Source: Google Maps Source: Google Maps Source: Google Maps

10 Where Are They Deployed? US 281 North, San Antonio Encino Rio to Marshall Rd Loop 1604 West, San Antonio New Guilbeau to Shaenfield Rd SH 71 at FM 973, Austin (Under Construction

11 When Are They Appropriate? High Major Street Volume Low Cross Street Through Volume For High Cross Street Volumes a Median U-Turn or (MUT) intersection may be applicable FHWA: Alternative Intersections & Interchanges: Informational Report (AIIR) Minor Road Total Volume (MRTV)/Total Intersection Volume (TIV) Ratio RCUT Throughput 15 to 30 percent higher than Conventional when MRTV/TIV Ratio is 0.1 to 0.2 Conventional Throughput 5 to 17 percent higher than RCUT when MRTV/TIV ratio greater than 0.25

12 Design Parameters Turnaround Location 400 1,200 ft from intersection AASHTO: ft spacing for Median U-Turn MDOT: 660 ft as standard spacing NCDOT: 800 ft minimum Considerations in Placement U-turn Queue Storage Signal Timing Driveways Travel Time

13 Design Parameters Channelization Left-Turn Lanes and Central Islands Triple Right-Turn Lanes

14 Median U-Turn Intersection: US 281 at Encino Rio Triple left-turn from Encino Rio

15 Design Parameters Turnarounds Two-Lane Turnaround Design Vehicles P WB-62 Accommodates truck off-tracking

16 Design Parameters Turnarounds Minimum Median Width: (Including turnaround lanes) 4-Lane: 62 ft 6-Lane: 40 ft Minimum ROW required at Turnarounds for WB Lane: 155 ft (nominal) 6-Lane: 165 ft (nominal)

17 Design Parameters Turnarounds MIN

18 Signalization Source: Alternative Intersection/Interchange Report 18

19 Signalization Signal Control One Controller Both major street approaches and turnarounds Two Controllers One for each direction on major street, controls intersection and turnaround for same direction Four Controllers Each direction of major street and turnaround operated by a separate controller Simple Operation

20 Signalization Vehicle Detection High Speed Major Roadway Advanced Radar Detection Presence Detection Radar Video

21 Signalization Pedestrian Considerations ADA Path Audible Pedestrian Signals Navigate complex intersection

22 Signalization Turnarounds Turnarounds treated like left-turn phases Under lower volume conditions, turnarounds could be unsignalized

23 Need for Additional Through Capacity Approximate Major Street Capacities: 700 to 900 veh per hour per lane (conventional) 1,250 to 1,350 veh per hour per lane (superstreet) Efficient signal phasing leads to increased green time. 1,800 veh per hour per lane uninterrupted flow Throughput at intersections can be increased with Auxiliary Through Lanes (ATL) A four lane road with an ATL in each direction could conceivably carry 3,750 veh per hour (1,250 x 3) in one direction through a superstreet intersection Used on Loop 1604 at Shaenfield ATL utilization can be improved with increased upstream storage length and downstream merge distance (Not supported by NCHRP 707)

24 Need for Additional Through Capacity Loop 1604 Auxiliary Through Lanes at Shaenfield Rd 1,000 Merge 2,200 1,000 1,400

25 Questions