Murray Boulevard and Farmington Road

Intersection

Sirisha Kothuri

Wei Feng

Ping Guo

Meead Saberi

CEE 550 Transportation Safety Analysis

Outline• Introduction

• Site Description

• Crash Data Analysis

• Literature Review

• Countermeasures

• Cost/Benefit Analysis

• Recommendations

Introduction

Map of Intersection

Murray Boulevard•2 lane undivided•Runs N-S

Farmington Road•2 lane undivided •Runs E-W

Intersection•City of Beaverton •4-leg signalized•Slight skew•High Volume

Aerial View of the Intersection

Site Description - I

Murray Blvd

Farmington Road

Apt7-Eleven

AptApt

Site Description - II

Signal at Intersection Illumination at Intersection

Barrier at Intersection Pavement Markings at Intersection

Site Description - III

Speed Limit Sign on Farmington Speed Limit Sign on Murray

Driveways near Intersection School Zone Signs

Site Description - IV

Heavy Vehicles

Queue Spillover to Adjacent Intersection

Volume

Source: City of Beaverton

Crash Data Analysis

• Oregon Transportation Safety Data Archive (ortsda)• Crash File

• Crashes for 4 Years (2003 -2006) at intersection

• Vehicle File• Information about vehicles involved in crashes at intersection

• Participant File• Information about drivers involved in crashes at intersection

• Crash Patterns at the Intersection • Time of Day• Type of Crash• Severity• Weather• Light Conditions

• Driver Characteristics

• Residence Status

• Gender• Age

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Time of the day

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ANGL-OTH O-STRGHT S-1STOP S-1TURN S-OTHER S-STRGHT

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FAT INJA INJB INJC PDO

Severity

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Crash Cause

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Crash Cause

Collision Diagram

Murray Blvd

Farmington Rd

Literature Review

• Rear End Crashes– Most common type at signalized intersections– Account for one-third of all reported crashes in US– Mostly PDO, sometimes severe injuries and fatalities occur

• Causes– Driver Behavior – Inattentive driving, smaller headways– Driver Age and Gender– Heavy Traffic Volumes– Dilemma Zone

Dilemma (Indecision) Zone

Source: Heng Wei, Characterize Dynamic Dilemma Zone and Minimize its Effect at

Signalized Intersections, Ohio Transportation Consortium (OTC), 2008

Dilemma (Indecision) Zone

Countermeasures1. Reduce speed limit on

approaches• 35 mph on Murray Blvd• 30 on Farmington Road

• Pros• Reduction in all types of crashes

• Cons• Increase in delay• Diversion of vehicles to other streets

Countermeasures

2. Advance Signal Warning Signs

• Murray Blvd & Farmington Rd

• Pros• Reduction in Rear End Crashes• Low cost• Easy Implementation

• Cons

Countermeasures3. Improve Signal Timing

• Optimize to ITE Standards

• Pros• Reduces Rear End PDO crashes

• Cons• Increases Fatal and Injury crashes

Countermeasures

4. Coordinated Signals• Coordinate adjacent intersections

• Pros• Allows progression of vehicles• Reduces all types of crashes

• Cons• Hard to implement

Cost Benefit Analysis

• Select Countermeasures– For each countermeasure, extract CRF– Calculate reduction in crashes– Calculate annual benefits and costs– Assume discount rate of 4%– Calculate NPV = NPVB – NPVC– Rank countermeasures in decreasing order of NPV

Cost Benefit Analysis

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

PDO INJC INJB INJA FATAL

Crash Type

Co

st (

$)

Cost of All Crashes at Intersection

Cost Benefit Analysis

1. Reduce vehicle’s approach speed limit

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

PDO INJC INJB INJA FATAL

Crash Type

Co

st (

$)

Before

After

Cost Benefit Analysis

2. Advance Signal Warning Signs

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

PDO INJ FATAL

Crash Type

Cos

t ($

)

Before

After

Conclusions & Recommendations

• Rear-end crashes are common at signalized intersections.

• Typical causes• Driver Behavior• Driver Age & Gender• Heavy Traffic Volumes• Dilemma Zone

• Countermeasures Ranking Based on B/C Analysis1. Install Advance Signal Warning Signs2. Reduce vehicle’s approach speed limit3. Signal Coordination

Acknowledgements

• Dr. Chris Monsere, PSU

• Jabra Khasho, City of Beaverton

• Baotu Ho, City of Beaverton