risk-based management of guardrails: site selection and upgrading

Center for Risk Management of Engineering Systems University of Virginia, Charlottesville

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RISK-BASED MANAGEMENT OF GUARDRAILS: SITE SELECTION

AND UPGRADINGPresented to

Project Steering Committee

Virginia Department of Transportation

by the

Center for Risk Management of Engineering Systems

April 17, 2000


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Agenda

• Introduction

• Risk-based screening of corridors

• Data representation for site screening

• Multiple objectives in the selection among candidate sites

• Software demonstrations

• Discussion


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Project TeamCenter for Risk Management of Engineering Systems

James H. Lambert, Research Assistant Professor of Systems Engineering, Center Associate Director

Yacov Y. Haimes, Quarles Professor of Systems Engineering and Civil Engineering and Center Director

Jeffrey A. Baker, BS/MS StudentChristian R. Baldwin

Irene A. JacoubMike R. Raker

Virginia Transportation Research CouncilWayne S. Ferguson, Research Manager

VDOT Richmond DistrictTravis Bridewell, District Traffic Engineer, Richmond District

Jeff Wilkinson, Transportation Engineer, Traffic Engineering Section, Richmond DistrictBaron Gissendaner


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Project Team (cont.)

Additional Steering CommitteeSteve Edwards, Transportation Engineer Senior, Traffic Engineering Division, Central Office

Paul Kelley, Transportation Engineer, Location and Design Division, Central OfficeCharlie Kilpatrick, Fredericksburg Resident Engineer, Fredericksburg District

Bob McCarty, Senior Field Operations Engineer, Federal Highway Administration - RichmondGinger Quinn, District Safety Officer, Traffic Engineering Section, Salem District

Nancy Berry, Transportation Engineering Program Supervisor, Location and Design Division, Central Office

Bill Bushman, Virginia Transportation Research CouncilAngela Tucker, Resident EngineerWillie Gentry, Resident Engineer

Alan Leatherwood, Resident Engineer


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Problem Statement

• Public and transportation-agency values concerning the location of roadway guardrails in need of clarification

• Concerns of Virginians for adequate guardrails high relative to the national norms

• VDOT Districts select locations for new guardrails based on citizen complaints, a general knowledge of roadway needs from local engineers, and accident history


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Problem Statement (cont.)

• Kentucky hazard-index point system (Kentucky Transportation Center Report KTC-89-39 "Warrants and Guidelines for Installation of Guardrail")

• Hundreds of candidate locations on the thirteen-county secondary system of Richmond District

• New Kent and Charles City County the focus of a related preliminary study in Richmond District


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Purpose and Scope

Identify attributes and develop associated cost-benefit-risk tradeoff methodology to

support screening and evaluation for guardrail site selection and upgrading with limited

available funding


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Purpose and Scope (cont.)

• Objectives– Review and evaluate what others have done– Adopt assessment methods– Develop tradeoff methodology– Specify and develop prototype databases


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Screening of Corridors

G u a rd ra ilC o vera ge

T o ta l a cc id e n tsR u n-o ff th e ro ad acc ide n ts

F ixe d O b je c t a cc ide n ts

A cc id e n tH is to ry

A D T

P o ss ib le S ea rch es


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Evaluation of Sites

C o s t H a za rd ch a ra cte ris ticsse verity, le n g th

R o a d ch a ra c te ris t icssh o u ld e r w id th ,s lo pe , cu rva tu re

P o ss ib le sea rch es


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Risk Based Screening of Corridors


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Motivation

A data-driven approach to assess accident risk and associated guardrail needs across Districts and Residencies


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Data Needs• Screening

– Guardrail inventories• Percent unprotected hazards

• Percent guardrail coverage

• Percent substandard guardrail

– Accident histories• FO accidents per DVMT

• Fatalities caused by FO accidents

– Average daily traffic

– Complaint records


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Data Needs (cont.)

• Evaluation– Cost (installation, upgrade)– Length of hazard– Severity of hazard– Shoulder width– Slope– Curvature


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Accident Statistics• Disadvantages

– Unreported accidents– Severity iceberg– First and most harmful event – Fatalities do not occur frequently enough to

be statistically predictive– Random nature of road accidents

(Adams, 1996), (Michie and Bronsted, 1994)


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Accident Statistics (cont.)

• Advantages– Available– Factual– Public interest

(Adams, 1996), (Michie and Bronsted, 1994)


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New Kent Case Study

• Initial data collection– Routes 600-608

• Corridor analysis– Collect data– Perform calculations (accidents per mile,

accidents per DVMT)– Generate tables and graphs


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Corridor Analysis

• Compare routes for frequency and severity of accidents

• Compare accident statistics with guardrail coverage

• Advantages– Reduce randomness of individual accidents– Use summary statistics available in HTRIS


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Corridor Analysis (cont.)

• Disadvantages– Does not focus on individual locations– E.g., many locations of mediocre severity vs.

one location of very high severity


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Data AcquisitionC

orrid

or

Leng

th in

Mile

s

DV

MT

Tot

al

Acc

idet

s

Fat

al A

ccid

ents

Inju

ry A

ccid

ents

PD

Acc

iden

sts

Per

sons

Kill

ed

Per

sons

Inj

ured

Am

ount

of

PD

FO

Acc

iden

ts

Run

off

the

roa

d A

ccid

ents

Fat

al a

ccid

entr

s du

e to

RO

R A

ccid

nets

Inju

ry A

ccid

nets

due

to

RO

R a

ccid

ents

PD

acc

iden

ts d

ue t

o R

OR

Acc

iden

ts

Per

sons

kill

ed d

ue t

o R

OR

Acc

iden

ts

Per

sons

inju

red

due

to R

OR

Acc

iden

ts

PD

due

to

RO

R A

ccid

ents

600 5.2 1932 2 0 1 1 0 1 $1,400 1 0 0 0 0 0 0 $0601 2.58 652 2 0 2 0 0 2 $15,200 2 1 0 1 0 0 1 $4,000602 0 0 0 0 0 0 $0 0 0 0 0 0 0 0 $0603 4.24 695 3 0 3 0 0 3 $18,000 2 2 0 2 0 0 2 $14,000604 2.2 734 1 0 1 0 0 1 $1,000 1 0 0 0 0 0 0 $0605 1.16 909 1 0 0 1 0 0 $1,700 1 0 0 0 0 0 0 $0606 7.4 2374 21 0 10 11 0 16 $113,415 9 10 0 7 3 0 13 $49,700607 0 0 0 0 0 0 0 0 $0 0 0 0 0 0 0 0 $0608 7.24 1818 10 0 2 8 0 6 $46,000 6 8 0 2 6 0 6 $43,000


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Corridor Screening0.82 605, 606 2.84 606 0.00 602, 607

6080.37 601, 603 1.35 606 0.00 600, 602,

606, 608 604, 605607

0.53 601, 605 1.22 606 0.00 602, 607606, 608

0.00 none 0.00 all 0.00 all0.00 none 0.00 all 0.00 all0.42 601, 603 1.35 606 0.00 602, 605

604, 606 6070.23 601, 603 0.95 606 0.00 600, 602

606, 608 604, 605607

0.41 605, 606 1.49 606 0.00 601-604, 608 607

0.06 606, 608 0.83 608 0.00 600-606607

Accidents per mile

PD ROR accidents per mile

Total accidents per mile

ROR accidents per mile

FO accidents per mile

Fatal accidents per mileFatal ROR accidents per mile

Injury accidents per mile

Injury ROR accidents per mile

PD accidents per mile

[Similar treatment of accident counts and accidents per DVMT]


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Corridor Screening (cont.)

• Example graph– Run off the road accidents per DVMT

0.00000

0.00100

0.00200

0.00300

0.00400

0.00500

600 601 602 603 604 605 606 607 608

Corridor

Acc

iden

ts p

er D

VM

T

Total Accidents Injury Accidents PD Accidents


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Data Representation for Site Screening


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Motivation

Need to organize data on many hazards protected and unprotected by guardrail on 40,000 miles of roadway across Virginia


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Sample of Guardrail InventoryR

OU

TE

:

CO

UN

TY

:

EX

IT #

:

RA

MP

:

NO

# O

F L

AN

FLO

W D

IRE

C

RT

# O

R L

T#

BE

G M

ILE

PO

EN

D M

ILE

PO

E R

UN

-ON

E M

AIN

RU

N

E R

UN

-OF

F

E A

TT

EN

UA

T

E F

OA

# e

nd t

reatm

ents

cost

of

end t

reatm

ent

Length

length

(ft

.)

cost

of

repl.

UP

GR

AD

E R

E

249NEW KENT 2 WEST RT 2.52 2.57 GR-6 GR-2 GR-6 2 5000 0.05 264 2640 N

249NEW KENT 2 EAST RT 2.58 2.52 GR-6 GR-2 GR-6 2 5000 0.06 317 3168 N

249NEW KENT 2 WEST RT 2.63 2.74 GR-6 GR-2 GR-6 2 5000 0.11 581 5808 N

249NEW KENT 2 WEST RT 10.5 10.5 FOA GR-2 GR-6 FOA 2 5000 0 0 0 N

249NEW KENT 2 WEST RT 10.5 10.5 GR-5 GR-2 GR-5 2 5000 0.03 158 1584 Y

249NEW KENT 2 EAST RT 10.5 10.5 FOA GR-2 GR-5 FOA 2 5000 0.01 52.8 528 Y

249NEW KENT 2 EAST RT 10.5 10.6 GR-5 GR-2 FOA FOA 2 5000 0.08 422 4224 Y

risk-based management of guardrails: site selection and upgrading

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