Lives Saved by FHWA Roadway Safety Programs

Forrest Council

Project Goals• Initial goal – Examine 2005-2012

changes in fatalities and crashes and estimate proportion of decrease related to FHWA programs (HSIP)

• Past studies indicate that major “causes” of crash/fatality change include not only safety programs, but also VMT and the economy.

What We Learned• It’s not just MVMT and changes in the economy,

but…• It will be difficult to tease out effects of roadway

treatment changes from vehicle changes from driver changes from economy changes…and

• New highly-rated NCHRP project will be awarded– “Identification of Factors Contributing to the Decline of

Traffic Fatalities in the United States (2014-G-17)”, – Much more money and longer time than we have.

• So we changed methods…

Experiment Methodology• Choose a couple of “popular” HSIP

treatment types• Find data on:

– Miles/locations treated in US– Before-treatment (fatal) crash rate per mile

or per location – Sound CMF giving percent decrease due

to treatment• Multiply together to estimate lives

saved in US (…simple, huh?)

HSIP Data (2009-10)Category Number of Projects 2009-2010 Total Spent 2009-2010

Intersection improvements 1290 $ 927,167,585 Pavement and shoulder widening 361 $ 653,445,225 Guardrails, barriers, attenuators 475 $ 344,807,950 Road safety audits 244 $ 241,236,409 Rumble strips 470 $ 158,094,102 Signs and markings 319 $ 116,296,550 Ped, bike, or disabled safety 96 $ 53,083,461 Skid resistance 82 $ 52,382,793 Rail crossing hazard elimination 27 $ 45,311,586 Roadside hazard removal 165 $ 40,053,227 Rail crossing safety features 41 $ 31,118,108 Traffic control at high crash locations 135 $ 31,073,714 Data improvement 58 $ 22,600,668 Wildlife crash improvement 21 $ 16,495,647 Traffic calming 13 $ 12,201,897 Safety planning 45 $ 11,657,108 Enforcement at work zones 37 $ 9,692,571 EMS priority at signals 5 $ 4,883,536 High risk rural roads 10 $ 1,811,579 Unlabeled category 9 $ 860,751 Signs at ped crossings and school zones 5 $ 612,477 Grand Total 4070 $ 3,071,205,109

Treatments Chosen• Trying to estimate lives saved due to

– Installation of new traffic signal, and/or– Installation of left-turn lanes at signalized

intersections– Shoulder rumble strips, and/or– Centerline rumble strips

Problems Encountered…• Need estimate of miles/locations treated in US

for each of these treatments.– HSIP does not have these data– Solution:

• a) Estimate percent, and thus amount, of total “intersection improvements” funds spent on new signal and left-turn lanes (and shoulder/centerline rumble strips)

• b) Estimate cost per installation and cost per mile• c) Divide a) by b) to get number of intersections treated

and number of miles of shoulder rumble strips installed– While HSIP has detailed data for some projects,

over 85% of projects had to be classified as “other” due to lack of detail in the database. …

Problems Encountered (cont)• So, where to find other data on…

– Percent of total intersection treatments funds spent on left-turn lanes and new traffic signals?

– Percent of total rumble strip treatments funds spent on shoulder or centerline rumble strips?

– National cost per location and per mile for these four treatments?

• HSIS Safety Project History files for CA, NC and OH!

Using the Safety Project Files• VHB extracted 2005 and later project data for

intersection and rumble strip treatments from each State’s project file.

• Findings:– Many of the intersection treatment entries in the OH file

are for “systems” (multiple locations), so not useful here.– No OH rumble strip entries after 2004– At times, difficulties in determining type of treatment and

whether single or multiple– Differences in categories used, spending patterns and in

cost/treatment

Example Intersection Treatment Expenditures

Subcategory NC

Percent of total costs

CA Percent of total

costs

NC Cost per Project

CA Cost per Project

Traffic signal - install new 13.5% 43.7% $ 82,455 $ 511,390 Lane addition - left-turn (signalized) 2.6% $ 461,400 Lane addition - left-turn (unsignalized) 15.9% $ 753,158 Lane additoin - left-turn (total CA) 18.4% Lane addition - left-turn (all approaches) 0.2% $ 94,375 Lane addition - left-turn (one major approach) 5.9% $ 182,650 Lane addition - left-turn (two major approaches) 3.4% $ 160,626 Lane addition - left-turn (unknown) 1.3% $ 257,000 Lane addition - left turn (total NC) 10.7% ….. Lane addition - left-turn (median openings, multiple locations) 2.4% $ 752,000 Lane addition - right-turn (one major approach) 1.6% $ 122,000 Lane addition - TWLTL 5.6% 6.3% $ 434,000 $ 1,141,000 …. Roundabout - install new 0.7% 8.6% $ 405,000 $ 3,889,000 ….

Traffic signal - general upgrade of existing 0.5% 6.7% $ 62,200 $ 334,556

Traffic signal - modify left-turn phasing of existing 0.3% 0.9% $ 22,013 $ 129,333 …. 0.0% $ 10,000 Intersection multiple treatments 56.2% 7.4% $ 202,378 $ 442,667

Other Issues to be Resolved• Find data on:

– Previous slides – just estimates of miles/locations treated in US

– Need before-treatment (fatal) crash rate per mile or per location • No such national data exists• Have some data from multi-state evaluation of shoulder

and centerline rumble strips• Still looking for before crash rates for intersections• Will need to convert total crash rates to fatal rates using

crash severity distributions – Need sound CMF giving percent decrease due to

treatment• Will have these!

Findings So Far• As expected, lots of assumptions will be

required to develop national estimates• HSIS project history data is helpful, but

does show differences between States– So re how to extrapolate differing NC and

CA data to national average – no clue yet!• “Simple” is never simple• This is still an experimental effort…

Questions?