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Lane Width Reallocations Based on 5-Year Crash Data

Lane Width Reallocations Based on 5-Year Crash Data. Richard C. Moeur, PE ADOT Traffic Design March 2007 edition. Flagstaff. Business Route 40 is primary east-west arterial street in Flagstaff Also known as “Route 66” Was US 66 from 1920s-1980s Currently signed as Historic US 66

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Lane Width Reallocations Based on 5-Year Crash Data

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  1. Lane Width ReallocationsBased on 5-Year Crash Data Richard C. Moeur, PE ADOT Traffic Design March 2007 edition

  2. Flagstaff • Business Route 40 is primary east-west arterial street in Flagstaff • Also known as “Route 66” • Was US 66 from 1920s-1980s • Currently signed as Historic US 66 • Currently owned & managed by ADOT • Will transfer to City of Flagstaff in future

  3. Crash Analysis • Part of design exception analysis for two B-40 paving projects in Flagstaff • Looked at all reported crashes from MP 195 - 200 • Jan 00 - Dec 04 (5 years) • Bike-MV crashes make up nearly 25% of all reported crashes in corridor • (75 out of 300+ total crashes)

  4. Bike-MV Crashes By Type

  5. Bike-MV Crash Severity

  6. Findings • 60% of bicycle-motor vehicle crashes involved wrong-way bicyclists • 50% of crashes involved wrong-way sidewalk or path riding • 63% of bike-MV crashes involved sidewalk or path bicyclists • 34% on north sidewalk BNSF OP - E Flg • 10% on south side path downtown - E Flg • 19% on other sidewalks (Milton, W 66)

  7. Findings • Only 1 crash involved an overtaking motorist colliding with a cyclist traveling in the roadway • Motorist cited for 28-735 • Only 1 fatal crash • at B-40 onramp at East Flag TI • Bicyclist at fault in 72% of crashes • Only 15% resulting in citation

  8. Hot Spots • 6bicycle-MV crashes at Milton / B-40 • 83% wrong way riding on sidewalk • 6bicycle-MV crashes at US 180 / B-40 • 83% sidewalk riding • 8bicycle-MV crashes at Enterprise / B-40 • 100% non-roadway cyclists • 62% involving pathway users (south side) • 75% involved wrong way riding

  9. Critical Issues • Wrong-way riding • Bicyclist approaches conflict points from unseen and unexpected direction • Sidewalk / path operation • Perceived as safer, but has higher crash risk • Bicyclists enter intersections unexpectedly

  10. Sidewalk/Path Conflicts -Left Turn From Parallel Road

  11. Sidewalk/Path Conflicts -Left Turn From Cross Road

  12. Sidewalk/Path Conflicts -Right Turn From Cross Road

  13. Critical Issues • Low apparent percentage of bicyclists riding in roadway • Outside lane widths not sharable per 28-815 • Drivers must change lanes to pass • Bicyclists may be uncomfortable occupying lane • Relatively high traffic volumes • Speeds consistent with urban arterial • apx. 40 MPH through much of corridor

  14. Lane Widths • AASHTO Green Book & ADOT Roadway Design Guide allow wide variety of lane widths • 12 ft is ‘basic’ width • But is “worst-case” situation for sharing • Looks sharable, but really isn’t • 10’ - 11’ are fully endorsed by AASHTO • 14’ is minimum sharable width • ARS 28-735 requires 3 ft passing distance for bicyclists

  15. Recommendations • Discourage wrong-way riding • Encourage on-street riding

  16. Recommendations • 60 ft roadway • (plus 2’ curb & gutter each side) • Old lane widths • 2 x 12’ lanes each direction + 12’ TWLTL • Revised lane widths • 10’ TWLTL • 11’ inside travel lanes • 14’ sharable outside travel lanes

  17. Existing Lane Configuration

  18. Recommended Lane Width Adjustments

  19. ADOT Bike Policy • ADOT will allow bike lanes or other facilities on state highways • However, ADOT requires local agency responsibility for bike-specific signs & markings • No agreement reached on B-40 (yet…?)

  20. Possible Bike Lane or Shoulder Configuration

  21. Questions? • Presentation can be downloaded from: • http://www.richardcmoeur.com/pres/b40flag.ppt

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