April 7, 2009 Presented by: Tom Welch State Transportation Safety Engineer
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Transcript of April 7, 2009 Presented by: Tom Welch State Transportation Safety Engineer
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April 7, 2009Presented by:
Tom WelchState Transportation Safety Engineer
Prepared with the Assistance of:
Dr. Tom Maze & Joshua Hochstein – Iowa State University
Iowa State University’s Center for Transportation Research and Education (CTRE) administers the following programs: Bridge Engineering Center • Center for Portland Cement Concrete Pavement Technology • Construction Management & Technology • Iowa Local Technical Assistance Program • Iowa Statewide Urban Design and Specifications• Iowa Traffic Safety Data Service • Midwest Transportation Consortium • Partnership for Geotechnical Advancement • Roadway Infrastructure Management Systems
IA-330/US-65/IA-117 & IA-330/F-17 Jasper County Intersections
Discussion of Design Alternatives
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DEFINING THE PROBLEMWith Traditional Expressway Intersection Design
• Typical Problem: Far-Side Right-Angle Collisions
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Typical Far-Side Right-Angle Collision
* Courtesy of University of Minnesota Intersection Surveillance System Test Bed at US-52 & CSAH-9, Goodhue County, MN
DEFINING THE PROBLEMWith Traditional Expressway Intersection Design
6:42 AM CDT
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Fatal Crash at US-151 & X-20, Springville, IA (Feb. 4, 2009)
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Locations:
IA-330 at County Road F-17 &
IA-330/US-65/IA-117
Jasper County
F-17
US
-65
IA-3
30
US-
65
IA-3
30
IA-1
17
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Fatalities:
Major Injuries:Sheridan, Wyoming84Betty SpanglerColfax, Iowa74Norma SmithChariton, Iowa82Walton CainNewton, Iowa34Christopher Carver
Broken Arrow, Oklahoma66Louise YoderMarshalltown, Iowa55Catherine LeonardColo, Iowa20Jennifer KnissMarshalltown, Iowa56Becky DeimerlyMarshalltown, Iowa78John MeadMarshalltown, Iowa66Mary MullIndianola, Iowa31Tiffany CooperChariton, Iowa77Betty CainWhitten, Iowa44Leslie HobsonEldora, Iowa46Lori Ledger
IA-330/US-65/IA-117
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IA-330/US-65 & US-65/IA-117Collision Diagram
2003 - 2008
Total = 43 or 7.17/year
4 Fatal
22 Injury
17 PDO
38 Right-Angle (88%)
36 Far-Side
2 Near-Side
2 Left-Turn Leaving (5%)
3 Rear-End (7%)
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CRASH TYPES: IA-330/US-65 & US-65/IA-117
Far-Side Right-Angle Crashes ARE a Problem!
95% of Right-Angle are “Far-Side” at IA-330/US-65 & US-65/IA-117
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CRASH SEVERITY: IA-330/US-65 & US-65/IA-117
Maze et al., 2004
[page 79]
More Fatal & Major Injury Crashes Occur at IA-330/US-65 & US-65/IA-117 Than on
Average
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MINOR ROAD DRIVER AGE IN RIGHT-ANGLE CRASHES AT IA-330/US-65 & US-65/IA-117
Elderly Drivers More Involved in these Collisions
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Fatalities:
Major Injuries:
Indianola, Iowa47Brian Cole
Nevada, Iowa79Opal Kassel*
Collins, Iowa16Craig Hudson
Kamrar, Iowa73Dorothy Donahue
Kamrar, Iowa78Walter Donahue
IA-330 and Co Rd F-17
* Driver was former DOT Director
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IA-330 & F-17Collision Diagram
2003 - 2008
Total = 15 or 2.50/year
2 Fatal
8 Injury
5 PDO
15 Right-Angle (100%)
11 Far-Side
4 Near-Side
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CRASH TYPES: IA-330 & F-17
Far-Side Right-Angle Crashes ARE a Problem!
73% of Right-Angle are “Far-Side” at IA-330 & F-17
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CRASH SEVERITY: IA-330 & F-17
Maze et al., 2004
[page 79]
More Fatal & Major Injury Crashes Occur at IA-330 & F-17 Than on Average
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MINOR ROAD DRIVER AGE IN RIGHT-ANGLE CRASHES AT IA-330 & F-17
Elderly Drivers More Involved in these Collisions
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Highway Crashes are Complex
Driver conditions and behavior A contributing factor in 95 percent of crashes Primary factor in 67 percent of crashes
Roadway design and environment A contributing factor in 28 percent of crashes Primary factor in 4 percent of crashes
Vehicle A contributing factor in 8 percent of crashes Primary factor in 4 percent of crashes
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YOUNG & ELDERLY DRIVERS Vision and Cognition
Challenges
Peripheral Vision is important to making judgements about placement, speed, and gaps in moving traffic– Young drivers are still developing peripheral
vision– Along with other vision changes, older drivers
also begin to lose peripheral vision
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The Teen Brain Is Still Under Construction
• Recent Scientific studies reveal that the teen brain is still under construction until about age 25.
• The Prefrontal Cortex is the last part to develop. It also controls: – risk-taking– judgment– impulse control– speed assessment– distance assessment– ability to handle distractions
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Medical Factors - Aging Drivers
Eye Lens
• The lens of the eye becomes cloudy and yellow with age, giving faulty information for driving decisions.
Depth Perception • With age, people lose depth perception and peripheral
vision making it harder to judge distance and speed
Needed Light
• A 50-year-old needs 5 times more light to read than a 20-year old.
• At 60 he’ll need 10 times more light
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ALTERNATIVES:
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National Academies of Science Transportation Research Board
Project 15-30 Median Intersection Design for Rural High-
Speed Divided Highways 2009
Principal Investigator:Dr. Thomas Maze PHD, P.E.
Joshua Hochstein, Ph.D. StudentIowa State University
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SIGNALIZATION
1) Creates Expressway Traffic Delay
2) Not Expected by Expressway Drivers
3) Don’t Necessarily Improve Safety (Change Crash Types, Not Severity)
4) Signals at the bottom of a hill are not desirable
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DRIVER EDUCATION:
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Does Driver Education Reduce Crashes?... No.
“The DeKalb County project-conducted in the U.S. in the late 1970s and early 1980s to evaluate the effectiveness of a comprehensive driver education program-stands as the most large scale, well-designed and ambitious effort to assess the impact of formal instruction.
Despite the different methods and statistical procedures that have been applied to the data, however, the findings have been extremely consistent and disappointing to the driver education community- driver education was not associated with reliable or significant decreases in crash involvement.”
Effectiveness And Role Of Driver Education And Training In A Graduated Licensing System:D. R. Mayhew and H. M. Simpson; • Date: 1996-09-09
Supported by the Insurance Institute for Highway Safety
The full report at www.Drivers.com
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Why Doesn’t Driver Education Reduce Crashes?
The studies conclude that typical driver training does not change behavior.
For example it: • does not motivate drivers to use what they have learned;• does not offset inherent risk behaviors;• does not address lifestyle and related psychosocial factors;• does not carry a sustained knowledge or performance expectation
that the driver will be tested or held accountable. (“Study only for the test and forget the rest.”)
Even worse, instruction• may encourage some drivers to feel over-competent enough to take
more risks, off-setting the value of learning safety tactics.
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Drivers Reality Check
• Knowledge doesn’t always translate to correct actions
• There is no substitute for experience
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INCREASED ENFORCEMENT:
“It is generally considered that fear of arrest and punishment causes drivers to conform better to traffic laws and regulations and thus reduces accidents. On the other hand, there is evidence to suggest that enforcement crusades have little lasting effect. For example, in several experiments vehicle speeds and driver behavior were recorded before and after an intensive enforcement effort. No significant changes were found either in speeds or in the number of law violations. Other studies have shown that many drivers ignore speed limit and speed zone signs that do not conform with their usual driving habits.”
Dr. Clarkson H. OglesbyStanford University
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Jasper Co. Sherriff Department Comments
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Failure To Yield Right-of-Way Crashes2004 -2008
5-year average per/year
Vehicle Type that got pulled in front of Average annual crashes reported
This depicts crashes involving a causal driver who failed to yield the right-of-way to another vehicle at an
intersection
8 ft
16ft
16 ft
17 ft
18 ft
66 ft
149 Motorcycle
738 Van or mini-van
1224 Pickup, van, small bus
4742 Passenger car
815 Sport utility vehicle
269 Large Trucks
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Cost Estimate: ≈ $7-10 Million
Safety Effectiveness Estimate:
≈ 60 – 80%
Diamond Interchang
e
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(Right-Left Configuration)
Cost Estimate: ≈ $3 Million ±
Safety Effectiveness Estimate: ≈ 40% Reduction
OFFSET T-INTERSECTION
Reduces Conflict Points from 42 to 26
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OFFSET T-INTERSECTIONS
26 Conflict Points
10 Crossing 16 Merge/Diverge
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OFFSET T-INTERSECTIONS
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J-TURN ALTERNATIVES
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THE J-TURN INTERSECTION
The J-Turn Intersection utilizes a directional median opening which closes the median to minor road traffic, but still allows all maneuvers (including left-turns) from the expressway.
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Closing the median eliminates direct crossing and left-turn maneuvers from the minor road, thus preventing far-side right-angle collisions. Emergency vehicles can still cross median.
THE J-TURN INTERSECTION
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All minor road traffic must turn right at the main intersection. Minor road drivers who wish to cross or turn left must do so indirectly via a downstream U-turn.
THE J-TURN INTERSECTION
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Out-of-the-way travel distance depends on spacing of U-turns, but 1500 to 5000 feet extra travel can be expected for a J-Turn Intersection.
However, because the movements involved are less complex, the total delay time for indirect left-turn & crossing maneuvers may be equivalent to that of direct maneuvers at a traditional at-grade intersection.
THE J-TURN INTERSECTION
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Interchanges also involve out-of-the-way travel
Typical Diamond = approximately 750 feet extra
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Typical loop ramp = approx. 2200 feet extra
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The J-Turn Intersection reduces the total number of intersection conflict points from 42 to 24, reduces the crossing conflicts from 24 to 4, and spreads out the conflict points over a larger area.
THE J-TURN INTERSECTION
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J-TURN INTERSECTION SIGNAGE EXAMPLE
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J-TURN ALTERNATIVE (IA-330/US-65/IA-117)
≈ 2250 feet ≈ 1100 feet
Approximate Proposed U-Turn Spacing From Main Intersection:
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J-TURN ALTERNATIVE (IA-330/F-17)
Approximate Proposed U-Turn Spacing From Main Intersection:
≈ 900 feet ≈ 1600 feet
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J-TURN INTERSECTION MARYLAND TESTIMONY
• City Council Members Initially Opposed to the J-Turn Design Option (Wanted Overpass/Interchange)
Couldn’t imagine how it could possibly work
Thought it would be too complex for elderly
• After J-Turn was constructed, it became obvious safety was improved
“Can’t deny that it was a measure important for safety”
U-Turn improves sight lines (provides a better visibility angle for viewing oncoming traffic in both lanes)
• J-Turn cheaper than an Overpass/Interchange
$800,000 vs $8,000,000 (Allows DOT to spend same $ on more projects across the state – Approximately 10 J-Turn Intersections can be built for the price of 1 interchange).
Video Clip
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J-TURN INTERSECTION SAFETY EVALUATION
All statistically significant reductions (90% confidence).
MARYLAND (US-301 & MD-313) 4 Years Before, 6 Years After
• 92% crash reduction overall (8.25 to 0.67 crashes/year)
• 100% reduction in right-angle collisions (22 to 0)
• 100% reduction in fatal/injury crashes (23 to 0)
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4 YEARS BEFORE
1/1/1997 – 10/31/2000
MARYLAND EVALUATION
33 Crashes Total
Right-Angle = 22 (67%)
FS = 18
NS = 4
In Median = 6 (18%)
Single-Vehicle = 4 (12%)
Mainline Rear-End = 1 (3%)
Fatal/Injury = 23 (70%)
85% “Preventable”
Includes 22/23 Fatal/Injury
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6 YEARS AFTER
1/1/2001 – 12/31/2006
MARYLAND
EVALUATION
4 Crashes Total
Right-Angle = 0
FS = 0, NS = 0
In Median = 0
Single-Vehicle = 3
Mainline Rear-End = 1
Fatal/Injury = 0
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Site #1 6 years before & after
Sites #2 & #3 3 years before & after
J-TURN INTERSECTION SAFETY EVALUATION
North Carolina (3 Site Average)
• 57% Crash reduction overall
• 97% reduction in right-angle collisions
• 100% reduction in far-side right-angle collisions
• 55% reduction in fatal/injury crashes
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J-Turn Intersection at IA-330/US-65 & US-65/IA-117 could…
Prevent 93% (40/43) of the collisions which occurred there over the last 6 years (38 right-angle & 2 left-turn leaving).
These collisions include the MOST SEVERE CRASHES (all fatal and minor injury as well as 4/5 major injury and 11/12 possible/unknown injury collisions).
THE J-TURN INTERSECTION
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J-Turn Intersection at IA-330 & F-17 could…
Prevent 100% of the collisions which occurred there over the last 6 years.
THE J-TURN INTERSECTION
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OTHER IOWA PROPOSED J-TURNS
US-151 & X-20, Springville, IA – Linn County
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US-151 & Springville Rd.
Janesville
Cedar Falls
US-218 & C-57 (W. Cedar Wapsi Road)
Black Hawk County
OTHER IOWA PROPOSED J-TURNS
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QUESTIONS?
Iowa State University’s Center for Transportation Research and Education (CTRE) administers the following programs: Bridge Engineering Center • Center for Portland Cement Concrete Pavement Technology • Construction Management & Technology • Iowa Local Technical Assistance Program • Iowa Statewide Urban Design and Specifications• Iowa Traffic Safety Data Service • Midwest Transportation Consortium • Partnership for Geotechnical Advancement • Roadway Infrastructure Management Systems
IA-330/US-65/IA-117 & IA-330/F-17 Jasper County Intersections
Discussion of Design Alternatives
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OTHER OPTIONS
Offset T-Intersection at
IA-330/US-65/ IA-117
(Right-Left Configuration)
(Alternative 1b)
US-
65
US
-65
IA-3
30
IA-3
30
IA-1
17
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OTHER OPTIONS
(Alternative 2a)
One Quadrant Interchange with T-
Intersection at IA-330/US-65/IA-117
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OTHER OPTIONS
(Alternative 2b)
One Quadrant Interchange with
Roundabout & T-Intersection at IA-330/US-65/IA-117
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OTHER OPTIONS
Two Quadrant Interchange at IA-330/US-65/IA-117
with Right-In, Right-Out Access
(Alternative 2c)
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OTHER OPTIONS
(Alternative 3b)
Folded Diamond Interchange at
IA-330/US-65/IA-117