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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4. 1995 NMSL Repealed; States Set Maximum Speed Limit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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2. Crash Analysis (Continued)
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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2. Crash Analysis (Continued)
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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2. Crash Analysis (Continued)
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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6. Corridor Analysis (Continued) - Westbound
I-10 EB Corridor Analysis
I 10 WB Corridor Analysis
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6. Corridor Analysis (Continued) - Westbound
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
85th % Speeds 10 mph > Posted Speed Limit
95th % Speeds 15 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
akhil.chauhan@arcadis-us.com
T. (225)-292-1004
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