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SW 8 th Avenue at SW 91 st Street Intersection Modification PowerPoint Presentation
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SW 8 th Avenue at SW 91 st Street Intersection Modification

SW 8 th Avenue at SW 91 st Street Intersection Modification

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SW 8 th Avenue at SW 91 st Street Intersection Modification

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  1. SW 8th Avenue atSW 91st StreetIntersection Modification Board of County Commissioners November 8, 2011

  2. Outline • Recommendation • Project Background and Location • Traffic Analysis • Comparison of Alternatives • Public Meeting • Recommendation

  3. Recommendation • Direct staff to proceed with the design of a signal with left turn lanes at the intersection of SW 8th Avenue at SW 91st Street and proceed with the bid phase when design is complete

  4. Project Background • 2005 Tower Road Network Study • Examined intersection capacities on Tower Road and surrounding network • Analysis based on Comprehensive Plan Policy 1.1.4 which adopts LOS D for motor vehicles as the minimum standard for collector and arterial roads • Recommended intersection modifications on Tower Road and at six other locations on the network • SW 8th Avenue at SW 91st Street included in the six network modifications • Design and construction funded with $500,000 of Impact Fees

  5. Project Background • Alachua County Mobility Plan • Adopted in April 2011 • Places emphasis on an interconnected roadway network • Extends SW 8th Avenue to SW 143rd Street and to SW 20th Avenue to serve as an east-west alternative to Newberry Road

  6. 8th Avenue Connector 8th Avenue Extension Tower Road From Archer Road to 8th Avenue 8th Avenue and 91st Street Intersection Improvements I-75 Overpass Widening

  7. Project Location SW 8th Avenue SW 91st Street Scenic Road Protection Area

  8. Traffic Data

  9. Roundabout Justification • Based on Florida Department of Transportation Roundabout Guide • Evaluates intersection in seven categories • Community enhancement • Traffic calming • Safety improvement • All-way stop control alternative • Low volume signal alternative • Medium volume signal alternative • Special conditions

  10. Roundabout Justification • Evaluation of contraindications (emergency response, right-of-way, etc.) • Results of roundabout justification • Roundabout justified as safety improvement, AWSC alternative and low volume signal alternative • Determined two possible contraindications • Emergency response route • Limited right-of-way • All contraindicating factors can be mitigated

  11. Comparison of Alternatives • Compared five alternatives • Existing stop control • Traffic signal with left turn lanes

  12. Signal Layout

  13. Comparison of Alternatives • Compared five alternatives • Existing stop control • Traffic signal with left turn lanes • Single lane roundabout with full right turn slip lane

  14. Roundabout 1 Layout

  15. Comparison of Alternatives • Compared five alternatives • Existing stop control • Traffic signal with left turn lanes • Single lane roundabout with full right turn slip lane • Single lane roundabout with modified slip lane

  16. Roundabout 2 Layout

  17. Comparison of Alternatives • Compared five alternatives • Existing stop control • Traffic signal with left turn lanes • Single lane roundabout with full right turn slip lane • Single lane roundabout with modified slip lane • Single lane roundabout without slip lane

  18. Roundabout 3 Layout

  19. Comparison of Alternatives • Compared five alternatives • Existing stop control • Traffic signal with left turn lanes • Single lane roundabout with full right turn slip lane • Single lane roundabout with modified slip lane • Single lane roundabout without slip lane • Compared alternatives in four areas • Operational efficiency • Environmental impacts • Safety • Costs

  20. Operational Impacts • Performed capacity analysis based on Comprehensive Plan Policy 1.1.4 • Based on Highway Capacity Manual methodolgies • Analyzed all options during the AM and PM peak hours in the current year and design year • Reviewed anticipated capacity of SW 24th Avenue at 91st Street roundabout vs. actual

  21. SW 24th Avenue at SW 91st Street

  22. Environmental Impacts • Evaluated three areas of environmental impacts • Potential tree impacts • Stormwater runoff • Gasoline consumption

  23. Tree Impacts - Signal

  24. Tree Impacts – Roundabout 1

  25. Tree Impacts – Roundabout 2

  26. Tree Impacts – Roundabout 3

  27. Tree Impact Summary

  28. Stormwater Impacts – Signal Stormwater - Signal

  29. Stormwater Impacts – Roundabout 1

  30. Stormwater Impacts – Roundabout 2

  31. Stormwater Impacts – Roundabout 3

  32. Stormwater Summary

  33. Gasoline Consumption

  34. Safety • Safety benefits of signals • Potential to reduce head-on, angle and left turn crashes • Positive direction to motorists, bicyclists and pedestrians • Alerts visually-impaired pedestrians • Safety benefits of roundabouts • Lower speeds through intersection • Provides pedestrian refuge • Reduces conflict points • Safety benefits decrease as more lanes are added

  35. Comparison of Intersections

  36. Costs • Evaluated total life-cycle costs taking into account: • Right-of-way acquisition • Design • Construction • Operation and maintenance

  37. Right-of-Way - Signal Existing Right-of-way

  38. Right-of-Way – Roundabout 1 Existing Right-of-way Proposed Right-of-way

  39. Right- of Way – Roundabout 2 Existing Right-of-way Proposed Right-of-way

  40. Right-of-Way – Roundabout 3 Existing Right-of-way Proposed Right-of-way

  41. Right-of-way Needs Summary

  42. Operation and Maintenance Summary

  43. * Assumes steel mast arm construction

  44. Public Meeting • Held on August 18, 2011 • Noticed through e-mail, mailouts, press release • Over 60 people in attendance • Received written comments from 26 individuals • Primary concerns included • Preserving scenic quality of 91st Street • Increased runoff • Costs • Right-of-way aquisition • Split preference between keeping AWSC and roundabout

  45. Recommendation • Direct staff to proceed with the design of a signal with left turn lanes at the intersection of SW 8th Avenue at SW 91st Street and proceed with the bid phase when design is complete

  46. Questions ?