GIS-Based Statewide Roadway and Area Risk Assessment Screening Tool

GIS-based Statewide Roadway and Area Risk Assessment Tool

By Michael Martin

2016 Traffic Safety Conference

College Station, Texas

Overview

The Concept

The Process– Defining a Common Geography

– Calculating Relative Area Crash Risk Metrics

– Creating a Composite Ranking

Statewide Area Risk Examples

To compare crash risks for a commonly identifiable geography relative to:

- Population Size

- Vehicle-Miles Travel (VMT)

- High & Very High Risk VMT

The Concept

1,024

Independent School Districts

Commonly Identifiable Geography

Fatal & Incapacitating Injuries per 1,000 inhabitants

Area Risk Relative to Population Size

Roadway Risk Assessment

Crashes Assigned2010-2014 Crashes Assigned

to Roadway Segments

Traffic Volume Ranges Defined

Area Type Functional Class

Volume Ranges

(ADT)

Low Medium High

Urban

Freeways <75,000 75,000 – 150,000 >150,000

Arterials <25,000 25,000 – 50,000 >50,000

Collectors <5,000 5,000 – 10,000 >10,000

Local* 0 – 20,000

Rural

Freeways <30,000 30,000 – 60,000 >60,000

Arterials <15,000 15,000 – 30,000 >30,000

Collectors <5,000 5,000 – 10,000 >10,000

Local* 0 – 15,000

*- Only one volume group.

Traffic Volume Ranges DefinedCrashes per Mile vs. Traffic Volume (ADT) for

Rural Freeways

Low HighMedium

0

10

20

30

40

50

60

70

80

90

100

0 20000 40000 60000 80000 100000 120000 140000 160000

Cra

she

s p

er

Mile

Traffic Volume (ADT)

Inflection points where the relationship changes.

Crash Risk Categories Assigned

Area Type Functional Class

Volume Ranges

(ADT)

Low Medium High

Urban

Freeways <75,000 75,000 – 150,000 >150,000

Arterials <25,000 25,000 – 50,000 >50,000

Collectors <5,000 5,000 – 10,000 >10,000

Local* 0 – 20,000

Rural

Freeways <30,000 30,000 – 60,000 >60,000

Arterials <15,000 15,000 – 30,000 >30,000

Collectors <5,000 5,000 – 10,000 >10,000

Local* 0 – 15,000

*- Only one volume group.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 6 7 8 9 10

Per

cen

t o

f Se

gmen

ts

Crash Rate (Crashes per Million Vehicle-Miles)

Inflection points where the relationship changes.

Low

Moderate

HighVery High

Crash Risk Categories AssignedCumulative Percent of Segment vs. Crash Rate for

Medium Traffic Volume Rural Freeways

All 20 combinations of:- Area Types- Functional Classes- Volume Ranges

Roadway Risk Assessment

Area Risk Relative to VMT

Fatal & Incapacitating Injuries per 10,000 VMT

Area Risk Relative to High & Very High Risk VMT

Percent High & Very High Risk VMT of Total VMT

Ranked #1 for Highest Risk

Metric Rankings

High Risk

Low Risk

Composite Ranking

OrderedLeast-to-Greatest

Ranked

Top 10 ISDs

Roadway Crash Risk Assessment

Fatal & Incapacitating

Injuries