Design Meets Reality Steve Allen Director Strategic Transportation - PowerPoint PPT Presentation

Design Meets Reality Steve Allen Director Strategic Transportation Investments Division Zane Pannell Transportation Project Specialist Strategic Transportation Investments Division

Agenda • Design Element Considerations • Post Construction Issues • Crash Statistics • Proposed Concept • Lessons Learned

Location

Alignment SB NB S.R. 109

13 Controlling Elements of Design 1. Design speed 8. Grade 2. Lane width 9. Stopping sight distance 3. Shoulder width 10. Cross slope 4. Bridge width 11. Vertical clearance 5. Horizontal 12. Lateral offset to alignment obstruction 6. Superelevation 13. Structural capacity 7. Vertical alignment

13 Controlling Elements of Design 1. Design speed 8. Grade 2. Lane width 9. Stopping sight distance 3. Shoulder width 10. Cross slope 4. Bridge width 11. Vertical clearance 5. Horizontal 12. Lateral offset to alignment obstruction 6. Superelevation 13. Structural capacity 7. Vertical alignment

Design Speed • Construction Let: April 2005 • Construction Completed: Summer 2013 • Principal Arterial • Rolling Terrain Traffic Data ADT (2003) 8,550 RDO1 ‐ TS ‐ 3A ADT (2023) 16,850 Directional Distribution 55% ‐ 45% Truck (ADT) 9% Truck (DHV) 6% V (Rural) 60 MPH

13 Controlling Elements of Design 1. Design speed 8. Grade 2. Lane width 9. Stopping sight distance 3. Shoulder width 10. Cross slope 4. Bridge width 11. Vertical clearance 5. Horizontal 12. Lateral offset to alignment obstruction 6. Superelevation 13. Structural capacity 7. Vertical alignment

Lane Width and Shoulder Width RDO1 ‐ TS ‐ 3A 48’ 4’ 24’ 10’

13 Controlling Elements of Design 1. Design speed 8. Grade 2. Lane width 9. Stopping sight distance 3. Shoulder width 10. Cross slope 4. Bridge width 11. Vertical clearance 5. Horizontal 12. Lateral offset to alignment obstruction 6. Superelevation 13. Structural capacity 7. Vertical alignment

Horizontal Alignment and Superelevation 2,440’ 1,146’ RDO1 ‐ SE ‐ 3

13 Controlling Elements of Design 1. Design speed 8. Grade 2. Lane width 9. Stopping sight distance 3. Shoulder width 10. Cross slope 4. Bridge width 11. Vertical clearance 5. Horizontal 12. Lateral offset to alignment obstruction 6. Superelevation 13. Structural capacity 7. Vertical alignment

Grade RDO1 ‐ TS ‐ 3A

13 Controlling Elements of Design 1. Design speed 8. Grade 2. Lane width 9. Stopping sight distance 3. Shoulder width 10. Cross slope 4. Bridge width 11. Vertical clearance 5. Horizontal 12. Lateral offset to alignment obstruction 6. Superelevation 13. Structural capacity 7. Vertical alignment

Stopping Sight Distance RDO1 ‐ TS ‐ 3A 2,449’ 2,449’>570’

Other Design Elements • Intersection sight distance • Offset turn lane • Turn lane storage

Other Design Elements • Intersection sight distance • Offset turn lane • Turn lane storage

Intersection Sight Distance RDO1 ‐ SD ‐ 5 Intermediate Semi ‐ Trailers Single Unit Truck 2,451’ 2,451’>750’ 2,451>1,330’

Other Design Elements • Intersection sight distance • Offset turn lane • Turn lane storage

Offset Turn Lane Design 48’ 96’ TDOT Roadway Design Section 2 Preliminary Design

Other Design Elements • Intersection sight distance • Offset turn lane • Turn lane storage

Turn Lane Storage Design TDOT Roadway Design Section 2 Preliminary Design 125’ 125’

So, What’s the Problem

Direction of Fatal Crash

Total Crashes Construction Completed

Injury Severity Construction Completed

Clearance Time V i = 0 mph V f = 22 mph S = 125 ft V= 70 mph a = ? t = 7.83 sec a = V f 2 ‐ V i 2 /2S s = ? a = 4.12ft/s 2 s = V*t s = 804 ft V= 60 mph t = 7.83 sec s = 125 ft s = ? t = 7.83 sec s = V*t s = 689 ft V i = 0 mph V f = 22 mph a = 4.12ft/s 2 t = ? t= V f ‐ V i /a

Existing Conflicts 32 Total Conflict Points

Conceptual Design

Conceptual Conflicts 14 Total Conflict Points

Lessons Learned • Visualize design • Safety considerations • Future training • Check all appropriate design vehicles

THANK YOU Quest?ons & Comments

Contact Information Steve Allen, Director Strategic Transportation Investment Division Tel: (615) 741 ‐ 2208 E ‐ mail: Steve.Allen@Tn.Gov Zane H. Pannell , E.I., Trans. Project Specialist Strategic Transportation Investments Division Tel: (615) 253 ‐ 2781 Email: Zane.Pannell@Tn.Gov

Conceptual Design