Reducing Engineering standards: GOOD OR Bad?

1. AASHTO Subcommittee on Design July 14, 2008 David C. O’Hagan, PE Florida DOT State Roadway Design Engineer Reducing Engineering standards: GOOD OR Bad?

2. SITUATION AASHTO ”Greenbook” FDOT Plans Preparation Manual (PPM) GOAL To reduce the cost of DOT projects without sacrificing safety and operational/functional characteristics. ANALYSIS DOT’s Costs: Pre-construction, right of way, construction, maintenance. Maintenance: Insignificant differential. User Costs: Safety AASHTO vsppm

3. AASHTO VS PPM OPTIONS • Maintain Status Quo: Use Variations Process to justify reduced criteria • Reduce PPM Criteria: Eliminates need for some Variation submittals • Revise Variation Requirements: Include a safety analysis to quantify impacts of reduced criteria.

4. AASHTO VS PPM RECOMMENDATION Option 3: Require a safety analysis with Design Variations for all new and reconstruction projects when reductions in critical design elements are being considered. JUSTIFICATION • Variations Process already working well. • Means to quantify safety impacts of cross-section decisions. • Consistent with including non-DOT costs in our decisions (user costs in pavement-type selection).

5. AASHTO vs. PPM • 2007 Study by Roadway Design Office • Construction Cost Differences Only • Interstate Widening (1.2%) • New Rural Freeway (8%) • New Rural Arterial (7%) • New Urban Arterial (10%) • New Overpass (21%)

6. AASHTO vs. PPM • 2008 Study by Roadway Design Office: Include right of way and maintenance costs with construction costs. • Rural Arterial Widening • Urban Arterial Widening • Interstate Widening • New Overpass Construction

7. SR 43 (US 301): Balm Rd to Gibsonton Dr. • Hillsborough County, 6.16 miles • Currently: Two-lane rural • New Design: Six-lane rural with sidewalk and shared-use path. • Design at 90% Complete when studied • Several Variations to eliminate ROW acquisition for typical section

9. SR 43 (US 301): Balm Rd to Gibsonton Dr. As designed PPM Design • Construction: $82,200,000 • Right of Way: $10,200,000 (Ponds) • DOT Costs: $92,400,000 • Crash (20 yr): $95,600,000 • DOT+User Costs (20 yr): $188,200,000 • Construction: $82,800,000 (+0.7%) • Right of Way: $26,300,000 (+158%) • DOT Costs: $109,100,000 (+18%) • Crash (20 yr): $88,000,000 (-8%) • DOT+User Costs (20 yr): $197,300,000 (+5%)

10. SR 50: US 19 TO CR 587 • Hernando County, 3.73 miles • Currently: Four-lane rural • New Design: Six-lane rural with sidewalk and shared-use path. • Design at 30% Complete when studied • Several Variations to eliminate ROW acquisition for typical section • Closed conveyance drainage system

12. SR 50: US 19 TO CR 587 AS DESIGNED PPM DESIGN • Construction: $49,200,000 • Right of Way: $0 • DOT Costs: $49,200,000 • Crash(20 yr): $85,600,000 • DOT+User Costs (20yr): $134, 800,000 • Construction Cost: $58,100,000 (+18%) (Walls were +17%) • Right of Way: $0* • DOT Costs: $58,100,000 • Crash(20 yr): $79,100,000 (-8%) • DOT+User Costs (20yr): $137,200,000 (+2%) * $32,800,000 if open conveyance & excluding business damages.

13. SAFETY IMPACT DIFFERENCES • SR 43 (Hillsborough) Side Slope: • HSM: +$6.6M • RSAP: +$9.4M Median Width: • HSM: +$1.0M • DOT Research: +$3.0M Combined: • HSM: +$7.6M SR 50 (Hernando) Side Slope: • HSM: +$6.0M • RSAP: +$9.7M Median Width: • HSM: +$0.5M • DOT Research: +$0.5M Combined: • HSM: +$6.5M

14. Accident Modification Factors • Undivided Divided

15. CONCLUSIONS Rural Widening: • Cost Savings are in ROW not construction. • Variations procedure working well. • AASHTO minimum criteria has significant safety impacts. • Recommend including typical section safety analysis in Variation process for non-3R projects. Additional Work: • Study Urban & Interstate Widenings • Study Overpasses • Review crash data of AASHTO-only states & compare to Florida