s24 speed studies ltc2013

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2012 ARCADIS27 February 20131

I-10 Speed Study

Texas State Line to Mississippi State LineMultiple Parishes

Akhil Chauhan, PE, PTOE, PTP

2.19.2013

Louisiana Transportation Conference

Imagine the result


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Safety

Moment


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DOTD Jody Colvin

Ty Hampton

Darryl Mack

ARCADIS

Thomas Montz

Justin Maderia

Reza Taromi

Joshua Chatelain

Acknowledgements


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Speed & Safety

Speed Limit Policy

Project Needs & Goals

I-10 Speed Study: Approach & Analysis

Data Collection

Roadway Attributes Inventory

Crash Analysis

Speed Analysis

GIS Database

Speed Profile

Conclusions

Outline


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1. Three HSM 2010 Roadway Safety Factors

Vehicle Regulated by NHTSA

Roadway Regulated by AASHTO

Human Un-Regulated

2. Vehicle Factors

Vehicle Safety Features Not Covered in this Study

3. Roadway Factors

Roadway Geometry, Site Characteristics

4. Human Factors

Driver Attention & Information Processing (PRT)

Operating Speeds

Operating Speed Regulated by Posted Speed Limit

Speed & Safety


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1. Enhances Safety

Limiting Function

Coordinating Function

2. Limiting Function

Upper Speed Boundary

Fines/Incarceration if Exceeded

Limits Probability & Severity of Crashes

3. Coordinating Function

Uniform Operating Speeds Reduced Potential for

Conflict

Speed Limit Purpose


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Speed Limit History

1. Pre 1974 States Set Speed Limit

2. 1974 1987National Maximum Speed Limit (NMSL) = 55 mph

3. 1987 States Set Speed Limit

Interstates Increased to 65 mph

4. 1995 NMSL Repealed; States Set Maximum Speed Limit

References: 1. http://en.wikipedia.org/wiki/National_Maximum_Speed_Law


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Regional Experience

1. Louisiana:

Maximum Posted Speed Limit = 70 mph

Posted Speed Limit > 70 mph if Engineering Study Warrants

Ex: I-49 Posted at 75 mph for ~ 200 miles

Opelousas to Shreveport

2. Texas:

Some Counties

Post 80 mph

1 Facility

Post 85 mph

References: 1. http://theadvocate.com/csp/mediapool/sites/Advocate/assets/templates/FullStoryPrint.csp?cid=340351&preview=y

2. http://www.dallasnews.com/news/transportation/20110406-some-texas-speed-limits-could-be-bumped-to-85-the-fastest-in-the-nation.ece


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Nationwide Speed Limits

References: 1. http://en.wikipedia.org/wiki/Speed_limits_in_the_United_States


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Need: Develop Database:

Interstate Highways

Major & Minor Arterials

Database Includes:

Existing Speed Profiles

Roadway Attributes

Crash Statistics

Speed Analysis Results

Goal: Provide Information to Improve Safety & Mobility (3Es)

Enforcement

Education

Engineering

Project Needs & Goals

References: 1. http://blog.ub.ac.id/midcool/category/sti/

I-10

I-12 I-20 I-49

I-55

Centralized Speed

Database


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Imagine the result


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Crash & ADT from 2008 - 2010 Highway Needs Database

GIS Shape Files

Traffic Volumes, Operating Speeds &Vehicle Headway

15 Base Sites

At Least 1 Site per Parish

25 Additional Sites In Urban Areas

Data Collection


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Crash Density, ADT, Geometric Attributes


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Crashes vs Milepoint


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Highway Needs Database & GIS Shape Files

Developed GIS Tool to Create Database

Field Verified

Databases using

Specially Developed

Data Entry Form

(ArcPad)

Roadway Attributes Inventory


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Field-Verified Data Collection Sites


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I-10 Speed Data Collection Sites

#1

#2

#3

#4 #8

#5

#6

#7#9

#10

#11

#12 #14 #16 - #21

#13 #15

#22

#24

#23

#25

#26

#27

#40

#39

#37

#35

#36

#38

Gulf of Mexico

Texas/Louisiana State Line Lafayette

New Orleans

Baton Rouge

References: 1. Google Earth

N

Louisiana\Mississippi State Line

## Denotes one of 15 Base Sites

#28

#29

#30

#32 to #34

#31


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By Direction By Parish

By Segment Characteristics 54% Rural vs.

46% Urban

By Crash Type By Crash Frequency - Plotted by Mile Point

Rate Comparison - Crash, Fatality & Injury Rates

vs. Statewide Average Rates

Crash Analysis

I 10 EB C h T b P i h


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2. Crash Analysis (Continued)

Crashes by Type - Eastbound

4. Project AnalysisI-10 EB Crash Types, by Parish

I 10 WB C h T b P i h


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Crashes by Type - Westbound

4. Project AnalysisI-10 WB Crash Types, by Parish


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Crash Analysis by Parish


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Crash Rates by Parish Urban, EB


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Crash Rates by Parish Rural, WB


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Crash Rates by Parish Urban, WB

I 10 EB C h R t S


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Crash Frequency & Rate Comparison - Eastbound

4. Project AnalysisI-10 EB Crash Rates Summary

I 10 WB C h R t S


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Crash Frequency & Rate Comparison - Westbound

4. Project AnalysisI-10 WB Crash Rates Summary


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Completed 40 Sites 80 Locations Wednesday 10 am to 2 pm

By Parish

Cumulative Speed Frequency Curve 50th/85th/95th Percentile Speeds

10 mph Pace

Speed Variance % Free-Flowing Vehicles

Speed Analysis


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Cumulative & Vehicles per Speed Interval

Speed Frequency Curves


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Speed Frequency Tables


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Operating Speed Maps


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Speed Frequency and Summary, by Site


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GIS Database

GIS D t b


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GIS Database


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1. Three Corridors Identified:

Uniform Crash Frequency & Severity

Uniform Roadway Attributes

> 60% Vehicles Traveling within 10 mph Pace

2. EB & WB 18 Miles Calcasieu Parish

3. EB 67 Miles Jefferson Davis, Acadia, Lafayette, St. Martin

WB 98 Miles Jefferson Davis, Acadia, Lafayette, St. Martin,

Iberville

4. EB & WB 44 Miles Ascension, St. James, St. John

Speed Profile

I 10 EB Corridor Analysis


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6. Corridor Analysis (Continued) - Eastbound

4. Project AnalysisI-10 EB Corridor Analysis

I 10 WB Corridor Analysis


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6. Corridor Analysis (Continued) - Westbound

4. Project AnalysisI-10 WB Corridor Analysis

I 10 EB Corridor Analysis


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I-10 EB Corridor Analysis

I 10 WB Corridor Analysis


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I-10 WB Corridor Analysis


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Crash Type

Rear-End, Side Swipe & Single Vehicle Crashes

80% to 90% of Crashes in each Parish

Crash Frequency

East Baton Rouge Parish

24% Crashes in 5% Study Length

Fatalities

Calcasieu Parish & Orleans Parish

28% of Fatalities in 17% Study Length

Injuries Orleans Parish

20% of Injuries in 11% Study Length

Crash Analysis Conclusions


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In General

50th % Speeds 5 mph > Posted Speed Limit



Lower Limit 10 mph Pace = Posted Speed Limit

Speed Analysis Conclusions

Over of I-10 traffic (51% to 75%) approximatelymatches or exceeds the posted speed limit.


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Determine how to improve safety and efficiency.

Enforcement

Promote Benefits of Limiting Function Promote Benefits of Coordinating Function

Education

Promote Importance of Posted Speed

Limit

Engineering

Update Posted Speed Limit

Corridor Analysis ConclusionsProper combination of 3 Es may be analyzed for

any corridor identified along I-10.


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Appropriate Posted Speed Limit Balances Safety & Mobility

85th Percentile Speeds

6 mph - 10 mph > Posted Speed Limit Across I-10

Database Summarizes Information to determine best way to

improve safety

Enforcement Education

Engineering

I-10 Speed Study Conclusions

This speed study provides database ofinformation to determine how safety &

efficiency of I-10 corridor can be optimized.


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Imagine the result

Questions or Comments?

Akhil Chauhan, PE, PTOE, PTP

[email protected]

T. (225)-292-1004

s24 speed studies ltc2013

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