Benefit-Cost Analysis of Florida High-Friction Surface TreatmentsBryan Wilson ,Brad Brimley, Jun Zhang, Anol MukhopadhyayTexas A&M Transportation Institute
Jim MillsPavement Analytics, LLC
Charles HolzschuherFlorida Department of Transportation
TRB 95th Annual MeetingJanuary 11, 2016Pavement Analytics, LLC
High-Friction Surface Treatments• Reduces horizontal curve road departures• Maintenance treatment for bridge decks• Polish resistant aggregate in polymer resin binder
HFST Crash Reduction Effectiveness
HFST > Roadway geometry correction (time intensive, costly)
Our ResearchObjectives• Evaluate the crash rates on different roadway section
types before and after HFST construction.• Compare benefit-cost ratios of different HFST
applications.
Scope• Identify all HFST projects in Florida.• Collect project data and before/after crash histories.• Calculate benefit-cost ratios by section type.
Procedures
Data Collection• Project location• Contract and bidding documents• Roadway geometry• Traffic characteristics• Construction duration• Crash statistics
Crash data• 5-yrs before HFST, and after HFST up to present• Exclude crashes outside HFST limits• Exclude crashes during construction period• KABCO coding• Crash rate:
Data Analysis• HFST Section Cost
• Actual project cost• Normalized project cost
• Bid unit HFST cost• Comprehensive unit HFST cost
Data Analysis• Benefit Calculation (3 methods)
• Total Crashes by KABCO (FDOT version)
• Total Crashes by average crash cost ($195,000)• Wet Weather by average crash cost ($195,000)
• Benefit-Cost per section type
Cost Type Cost Per Crash By Type (Thousands $) K A B C O
Lost Quality of Life $7,750 $919 $252 $108 $31.8 Economic $1,400 $82.0 $23.7 $19.5 $10.4 Societal Impact (Total Cost) $9,140 $1,001 $276 $128 $42.3 FDOT Societal Impact (Total Cost) $10,000 $819 $163 $100 $6.50
Results
Project Data• 23 total HFST projects
• Mainline and bridge deckapplications
• 47 unique HFST sections• 38 sections w/ data
• 16 tight curves• 16 wide curves/tangents• 6 intersections/ intersection
approaches
Mainline (Dev 333) Bridge deck (TSP 403)
Radius
Section Length
Traffic Volume
Existing Surface Type
HFST Aggregate Type
Crash Rates (Total Crashes)
Crash Rates (Wet Weather Crashes)
Change in Crash Rate
HFST Unit Cost
Normalized HFST Project Cost
Benefit-Cost
Benefit-Cost
Conclusion
Findings SummaryCrash reduction with HFST • Most effective on tight curves:
• Average 32% reduction of total crashes.• Average 75% reduction of wet weather crashes.
• Wide curves / tangents:• No crash history = no change in crash rate.
• Intersections/intersection approaches:• Effectiveness undetermined. • In some cases, total crashes were reduced (41%)• and increased in others (151%).
Findings SummaryHFST Cost• Average bid unit cost: $34/yd2.• Average comprehensive unit cost: $59/yd2
• Average normalized HFST project costs:• Tight curves - $172,000• Wide curves / tangents - $560,000• Intersections / int. approaches - $476,000
Findings SummaryBenefit-Cost Ratios (crash reduction perspective)• Most cost-effective on tight curves:
• 24.5 for total crashes (KABCO weighting).• 26.0 for total crashes (avg. weighting).• 18.0 for wet weather crashes (avg. weighting).• Individual projects with HIGH ratios of 118, 65, 56, and 30.
• Wide curves / tangents:• No benefit on average.
• Intersections / intersection approaches:• Avg. benefit-cost ratio undetermined. • Positive B-C ratio in some cases (50, 33, 20) • Negative B-C ratio in other cases (-66, -32, -23)
Recommendations• Continue promoting HFST for crash reduction around tight
curves with a history of crashes.• Reduce emphasis of safety benefits when considering
HFST on wide curve/tangent sections that have no history of crashes.
• Evaluate benefit-cost of HFST as a maintenance treatment of concrete bridge decks.
• Evaluate in-detail the nature of crashes at intersection/ intersection approach sections and how the crashes may relate to the installation of HFST.
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