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.

Thank You.Questions?

Bryan Wilsonb-wilson@tti.tamu.edu

Pavement Analytics, LLC