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NCHRP Project 17-35: Evaluation of Safety Strategies at Signalized Intersections

 

 

Evaluations of Low Cost Safety Improvements Pooled Fund Study

 

PPT version for Printing

Low Cost Evaluations

Shawn A. Troy, PE
North Carolina DOT – Traffic Engineering Branch

Low Cost Pooled Fund TAC Meeting
June 20, 2007

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Low Cost Evaluations Traffic Safety System View alternative text
Low Cost Evaluations Low Cost Evaluations
Low Cost Evaluations Low Cost Evaluations
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Low Cost Evaluations Low Cost Evaluations

Directional Crossover – 1

  • Problem Statement:
    High volume of traffic on mainline
    Vehicles attempt left turns from the side road
    Resulting in high number of crashes at the location
    Signal not considered due to signals on either side of intersection within 600’
  • Countermeasure:
    Installation of a Directional Crossover
    Cost: $55,000
    Project completion – June 30, 2000
    5 Years and 7 Months – Before and After Data


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Picture 1 Looking East on Main Picture 2 Looking East on Main
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Picture 3 Looking East on Main Picture 4 Looking West on Main
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Before Collision Diagram
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After Collision Diagram
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Results

Treatment Information
  Before After Percent Reduction (–)
Percent Increase (+)
Total crashes 45 70 55.6
Total Severity Index 3.1 4.5 42.3
Frontal Impact Crashes 33 43 30.3
Frontal Severity Index 3.4 5.5 62.5
Volume 13400 17000 26.9
 
 
Treatment Injury Crashes
  Before After Percent Reduction (–)
Percent Increase (+)
Fatal 0 1 N/A
Class A 0 0 N/A
Class B 5 4 –20.0
Class C 8 19 137.5
Property Damage Only 32 46 43.8
 
 
Frontal Injury Crashes
  Before After Percent Reduction (–)
Percent Increase (+)
Fatal 0 1 N/A
Class A 0 0 N/A
Class B 5 3 –40.0
Class C 6 13 116.7
Property Damage Only 22 26 18.2
 
 
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Directional Crossover – 2

  • Problem Statement:
    Congestion and high volume of traffic at the intersection
    Vehicles attempt left turns from the side road
    Resulting in high number of crashes at the location
  • Countermeasure:
    Installation of a Directional Crossover
    Cost: $30,000
    Project completion – April 9, 1999
    6 Years and 10 Months – Before and After Data
 
 
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Looking South on US 158 Picture 1 Looking South on US 158 Picture 2
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Looking South on US 158 Picture 3 Looking South on US 158 Picture 4
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Looking North on US 158 Picture 1 Looking North on US 158 Picture 2
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Looking North on US 158 Picture 3 Looking North on US 158 Picture 4
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Before Collision Diagram  
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After Collision Diagram  
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Results

Treatment Information
  Before After Percent Reduction (–)
Percent Increase (+)
Total crashes 37 26 –29.7
Total Severity Index 12.2 3.8 –68.5
Frontal Impact Crashes 33 4 –87.9
Frontal Severity Index 11.3 6.6 –41.8
Volume 22000 29400 33.6
 
 
Treatment Injury Crashes
  Before After Percent Reduction (–)
Percent Increase (+)
Fatal 1 0 –100.0
Class A 3 0 –100.0
Class B 5 2 –60.0
Class C 10 8 –20.0
Property Damage Only 18 16 –11.1
 
 
Frontal Injury Crashes
  Before After Percent Reduction (–)
Percent Increase (+)
Fatal 1 0 –100.0
Class A 2 0 –100.0
Class B 5 0 –100.0
Class C 10 3 –70.0
Property Damage Only 15 1 –93.3
 
 
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Before Collision Diagram
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After Collision Diagram
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Results

Frontis St Influence Information
  Before After Percent Reduction (–)
Percent Increase (+)
Total crashes 5 29 –29.7
Total Severity Index 4.0 3.0 –23.2
Frontal Impact Crashes 3 22 633.3
Frontal Severity Index 1.0 3.0 201.0
Volume 20850 27650 32.6
 
 
Influence Injury Crashes
  Before After Percent Reduction (–)
Percent Increase (+)
Fatal 0 0 N/A
Class A 0 0 N/A
Class B 0 2 N/A
Class C 2 6 200.0
Property Damage Only 3 21 600.0
 
 
Influence Injury Crashes
  Before After Percent Reduction (–)
Percent Increase (+)
Fatal 0 0 N/A
Class A 0 0 N/A
Class B 0 2 N/A
Class C 0 4 N/A
Property Damage Only 3 16 433.3
 
 
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Centerline Rumble Strips

  • Problem Statement:
    11.5 mile segment of rural 2–lane roadway
    Section bordered on North and South by 4–lane divided roadway segments
    North is a 65 mph full control access segment
    South is a 55 mph partial control access segment
    Construction began in December 4, 2004 to convert 2–lane segment to 4–lane divided roadway to match North and South segments
    During first 6 months of construction – 4 Fatal Head–On Crashes occurred


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  • Fatal Crash History:
    January 1999 through June 2005
Left of Center Fatal Crashes on US 421 Chatham County from 1999–2005
Date Time Vehicle Type of Accident Speed Driver Direction Age Driver's Local/Out of State # Killed Comments
1 10/10/99 8:15 PM Car/Tractor Trailer Crossed center line 55 mph NB 21 from Cameron, NC 1 Alcohol
2 5/18/01 3:40 PM Car/Tractor Trailer Crossed center line 55 mph SB 70 from Fletcher, NC 1  
3 10/5/01 8:45 PM Car/Tractor Trailer Crossed center line 60 mph SB 49 from Greensboro 1  
4 11/23/01 8:30 PM Single Car Crossed center line 70 mph NB 19 Fort Bragg 2 Driver Charged with DWI
5 5/16/03 8:45 AM Car/Tractor Trailer Crossed center line 55 mph NB 52 Pennsylvania 1  
6 8/24/04 1:43 AM Car/Tractor Trailer Crossed center line 70 mph NB 46 Siler City 2 Driver Charged with DWI
7 10/30/04 3:15 AM Car /Car Crossed center line 55 mph SB 19 Sanford 3  
8 2/22/05 6:30 AM Car/Tractor Trailer Crossed center line 55 mph NB 24 Siler City 1  
9 3/16/05 ####### Car/Tractor Trailer Crossed center line 50 mph NB 46 from Greensboro 1  
10 5/3/05 ####### Car/Tractor Trailer Crossed center line 55 mph NB 31 Washington 1 Vehicle unable to stop for slowed traffic
11 5/26/05 ####### Car/Tractor Trailer Crossed center line unk NB 73 Sanford 1  
  • Countermeasure:
      Installation of Centerline Rumble Strips for the remainder of the construction project
      Centerline rumble strips were installed in 5 days between July 19–28, 2005
      Total cost for the installation of milled rumble strips, traffic control and motorcyclist signing was $ 34,388
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Before period(3 Yrs)
7/1/2002 – 6/30/2005
After period(1.5 Yr)
8/1/2005 – 1/31/2007
 
Total Crashes Crashes/ Yr Total Crashes Crashes/ Yr Percent Change
193 64.3 58 38.7 –39.9
Lane Departure Crashes* Crashes/ Yr Lane Departure Crashes* Crashes/ Yr  
102 34.0 15 10.0 –70.6
Correctable Crashes** Crashes/ Yr Correctable Crashes** Crashes/ Yr  
31 10.3 3 2.0 –80.6
Correctable Crashes
Crash Severity
Crashes Per Year
Before
Crashes Per Year
After
Percent Change  
Fatal 2.0 0.7 –66.7  
Class A Injury 1.0 0.0 –100.0  
Class B Injury 0.7 0.7 0.0  
Class C Injury 1.0 0.0 –100.0  
PDO 5.7 0.7 –88.2  


* Lane Departure Crashesinclude the following crash types
Ran Off Road – Right, Ran Off Road – Left, Ran Off Road – Straight, Overturn/Rollover, Other Non–Collision,
Fixed Object, Parked Motor Vehicle, Head On, Sideswipe – Same Direction, and Sideswipe – Opposite Direction.

** Correctable crashes involve at least one vehicle crossing the centerline.
Note that avoidance, weather, and passing related crashes were not included.
Avoidance Crashes consist of the following: Other vehicles, movable objects, deer, pedestrians,
mechanical problems, flat tires, blown tires, and medical problems.
Also, only crashes where the first vehicle maneuver involves veering left are included.


Safety Evaluations

  • Safety Evaluation Group
    2004 15 projects 15
    2005 95 projects (10 to be complete) 105
    2006 102 projects (5 to be complete) 107
    2007 41 projects (145 to be complete) 186
    Above are projects completed through 2002 102
    projects will be assigned from the 2003 completions
    190 Spot Safety project evaluations are on the web that
    were completed through December 31, 2006:


 






AASHTO TIG–CMB

  • Key Topic Areas
    – Contact Information
    – Background and Problem Identification
    – Roadway Design Issues
    – Maintenance Issues
    – Benefits and Evaluation
    – System Threats
    – Barrier Design

AASHTO TECHNOLOGY
IMPLEMENTATION GROUP(TIG)
CABLE MEDIAN BARRIER(CMB)
WEBSITE LAUNCH

Please visit http://tig.transportation.org then click on CMB to find answer to your state’s key question about Cable Median Barriar.
AASHTO TIG–CMB AASHTO TIG–CMB

Contact Information

SHAWN A.TROY, PE
(919)–2897
stroy@dot.state.nc.us
Contact Information
Traffic Safety Unit Website:http://www.ncdot.org/doh/preconstruct/traffic/TSU/default.html

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