geometric design elements to reduce wrong-way (ww)...
TRANSCRIPT
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Hugo Zhou, Ph.D., P.E.
Department of Civil Engineering Auburn University
March, 2017
Geometric Design Elements to Reduce Wrong-Way (WW) Entry
at Freeway Interchanges
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2017/3/24
(Image: Google Earth)
WW Entry: Gas Station
U.S.280 & North College St. Auburn, AL
48h video
4:30 p.m., October 27-29, 2016
15 WW movements
Gas Station
Why People Drive Wrong-way?
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https://www.youtube.com/watch?v=AU5KH7jKrU4
15 WW movements
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1. Wrong-Way Driving(WWD) Crash History
2. Existing Design Guidelines
3. Wrong-Way(WW) Movements at Different Interchanges
4. Effect of Geometric Elements on WWD
WWD Crash Analysis
Field Study of GPS Devices
5. Proven Geometric Design Elements
Presentation Outline
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Wrong-Way Driving(WWD) Crash History 01
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- 4 %
+0.2%
National Trend of WWD Fatal Crashes (2004-2011)
WWD is rare
but very
severe!!!
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2% or higher 1% - 2% Below 1%
Average and Percentage of WWD Fatalities in Each State (2004-2011)
2.5%
(IDOT WWD Guideline)
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Number of WWD Crashes in Alabama
Year
2009 2010 2011 2012 2013 Total
Freeway Crashes 11,023 11,433 11,967 11,258 11,358 57,039
WWD Crashes 17 16 25 16 19 93
Percent 0.15% 0.13% 0.20% 0.14% 0.16% 0.16%
No. of Persons
Killed 4 2 6 2 4 18
A-Injury 7 4 18 7 11 47
B-Injury 2 10 6 7 3 28
C-Injury 3 1 6 1 5 16
PDO 22 27 44 38 25 156
No. of Crashes
Freeway Fatal Crashes 77 93 88 86 83 427
WWD Fatal Crashes 4 2 4 2 2 14
Percent 5.2% 2.2% 4.5% 2.3% 2.4% 3.3%
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Top Counties in Number of WWD
Ranking County No. of WWD Crashes Percent
1 Jefferson 31 33.3%
2 Mobile 14 15.1%
3 Baldwin 5 5.4%
3 Madison 5 5.4%
5 Montgomery 4 4.3%
5 St Clair 4 4.3%
7 Butler 3 3.2%
7 Macon 3 3.2%
7 Tuscaloosa 3 3.2%
Total 72 77.4%
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Top Five Routes in terms of WWD
Route Frequency Percent Length (mi) Percent of Total Mileage
I-65 29 31.2% 367.0 35.4%
I-59 25 26.9% 241.4 23.3%
I-10 10 10.8% 66.3 6.4%
I-20 7 7.5% 214.7 20.7%
I-85 6 6.5% 80.0 7.7%
Total 77 82.8% 969.4 93.6%
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Area Type
Image: Google Earth
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Temporal Distribution: Month
4
8
13
4
15
5 6
4
6 6
13
9
0
2
4
6
8
10
12
14
16
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Cra
sh F
req
uen
cy
Month
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13
Temporal Distribution: Day
15
6 7
5
16
20
24
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Cra
sh F
req
uen
cy
Days of the Week
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Temporal Distribution: Hour
18
25
6 6 4
3
12
19
0
5
10
15
20
25
30
12:00-2:59 3:00-5:59 6:00-8:59 9:00-11:59 12:00-14:59 15:00-17:59 18:00-20:59 21:00-23:59
Cra
sh F
req
uen
cy
Hour
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WW Driver Characteristics: Age
Age Group No. of Drivers Percentage of Total
Less than 24 17 18.3%
25-34 21 22.6%
35-44 14 16.1%
45-54 8 8.6%
55-64 4 4.3%
Over 65 24 25.8%
Unknown 5 5.4%
Total 93 100.0%
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WW Driver Characteristics: Condition
Apparently Normal
25%
Asleep, fainted, fatigued, etc.
1% Illness
1% Physical
Impairment 4%
Under the Influence of
Alcohol/Drugs 46%
Other/unknown 23%
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Roadway Lighting Condition
31
35
2
22
2 1
0
5
10
15
20
25
30
35
40
Darkness-RoadLit
Darkness-RoadNot Lit
Dawn Daylight Dusk NA
Cra
sh F
req
uen
cy
Lighting Condition
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General Issues with Geometric Design
Driveways Close to Exit Ramp
Channelizing Island and Angular Break
30% Locations with Raised Median
Exit Ramp Driveway
Flush Median
Image: Google Earth
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Existing Design Guidelines 02
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AASHTO
Green Book
Chapter 10.9.5: Genera Design Consideration of Interchanges – WW Entry
ATSSA
Emerging Safety Countermeasures for Wrong-Way Driving
IDOT
Chapter 2: Signs,
Pavement Markings, and
Traffic Signals
Chapter 3: Geometric
Design Elements
Chapter 4: Advanced
Technologies,
Enforcement, and
Education
Other
DOTs
WSDOT
TxDOT
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Geometric Design Examples
Geometric Elements
• Raised Median
• Control Radius
• Channelizing Island
Geometric Design Examples of Conventional Diamond
Interchanges
Geometric Design Examples of Partial Cloverleaf Interchanges
21
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Geometric Elements
22
Raised Medians: Wherever left-turn wrong-way maneuvers from a crossroad onto exit ramps are a
major of concern.
Exit Ramp
Entrance Ramp
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Geometric Elements
23
Median Barrier: When the proximity of exit and entrance ramps can cause confusion to
drivers (e.g. Trumpet interchanges).
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Geometric Elements
24
NOTE: Concrete barriers or guardrails as median barriers can cause a sight
distance problem for drivers on the crossroad if used to separate adjacent
entrance and exit ramps at partial cloverleaf interchanges.
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Geometric Elements
25
Note: If a curve is used as the control radius, the crossroad centerline, and not
the edge of the crossroad, should be considered as the tangent line.
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Geometric Elements
26
Channelizing Island: An effective way to reduce wrong-way movements,
especially among older drivers. This element can reduce the width of the exit
ramp throat.
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Geometric Design Examples of Conventional Diamond Interchanges
27 Two-Lane Crossroad Design Divided Crossroad Design
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28
Geometric Design Examples of Conventional Diamond Interchanges
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Wrong-Way(WW) Movements at Different Interchanges 03
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Wrong-Way Entry
Common entry points
Entering from the exit ramp – the most prevalent one!
Cross the median
U-turn on freeway
Partial cloverleaf (Parclo) interchanges among most susceptible interchanges in terms of WWD entry
Close exit and entrance ramp (two-way ramp)
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Geometric Design Examples of Partial Cloverleaf Interchanges
32
Typical Ramp-Crossroad Design for a Two-Quadrant Partial Cloverleaf Interchange Proposed by IDOT
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Geometric Design Examples of Partial Cloverleaf Interchanges
33
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Effect of Geometric Elements on WWD 04 WWD Crash Analysis
Field Study of GPS Devices
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1) Control Radius
2) Median Type on Crossroads
3) Median Width on Two-way Ramps
4) Intersection Balance
5) Distance to Access Point in the Vicinity of the Interchange
6) Intersection Angle
7) Channelizing Island
Potential Geometric Design Elements
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IDOT Design Guidelines
Radius from Crossroad
Radius to Crossroad
Channelizing Island
Median on Crossroad
Median on Two-way Ramp
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WWD Crash Analysis
WWD crash data from Alabama(5 years) and Illinois(10 years)
172 two-way ramps at 97 parclo interchanges
65 WWD crashes originating from 54 locations
Binary logistic regression analysis, significant level p=0.05
Odds Ratio (OR) as the relative measure of effect
Crash data and study method
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Logistic Regression Analysis Results
Variable Category OR
Control/Corner Radius from Crossroad
50 ft and less Reference
51 to 60 ft 1.76 61 to 70 ft 1.55
71 to 80 ft 1.97 81 to 90 ft 4.67 91 to 100 ft 3.39 More than 100 ft 2.27
Type of Median on Crossroad
Non-traversable Reference
Traversable 1.94 Median between Exit and Entrance Ramps
10 ft and less Reference
11 to 20 ft 1.13 21 to 30 ft 1.89 31 to 40 ft 0.25
41 to 50 ft 0.79 51 to 60 ft 0.28 More than 60 ft 0.19
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Logistic Regression Analysis Results (continued)
Variable Category OR
Distance to Access Point in the Vicinity of the Interchange
300 ft and less Reference
301 to 600 ft 1.16
601 to 900 ft 0.68
901 to 1,200 ft 0.69
1,201 to 1,500 ft 0.60
More than 1,500 ft 0.63
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WSDOT Design Guideline
Intersection Balance
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A Real-World Example of Intersection Balance
>60% L
(Google Earth)
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Impact of Intersection Balance on WW Crashes
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Objective: To determine the minimum spacing between exit ramps and access
points based on the accuracy of common GPS devices
5 GPS Devices (Apple map, Google map, Garmin nuvi 2557/ 2797/ 40)
10 Interchanges with Close Side Streets
Field Study of GPS Devices
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Field Experiment Scenario Design
a: Spacing between side streets and exit ramps b: Field test driving routes
(Google Earth)
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% of Wrong Announcement by GPS VS. Access Spacing
Cumulative percentage of “Turn Right” statements by GPS devices/navigation
600 ft
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Proven Geometric Design Elements Can Reduce WWD 05
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Small Crossroad
Corner Radius
> 30ft Ramp
Median Width
< 60% L Intersection
balance
< 600ft
Access point
Control/Corner Radius
less than 80ft from
Crossroad will be less
likely to cause WWD.
Traversable median
are twice more
prone to WWD
entries.
Median width of 30+ft
between ramps was found
to be less vulnerable to
WWD entries.
Intersection balance can
affect drivers’ view of
entrance ramps, resulting
in more WWD crashes.
Access points located
less than 600ft to the
exit ramps increase the
likelihood of WWD
crashes.
Proven Geometric Design Elements (WWD Crash Analysis)
Non-Traversable
Crossroad Median
![Page 48: Geometric Design Elements to Reduce Wrong-Way (WW) …conferences.dot.state.al.us/.../Geometric_Design.pdfProven Geometric Design Elements (WWD Crash Analysis) Non-Traversable Crossroad](https://reader035.vdocuments.site/reader035/viewer/2022071113/5fe9e09fd7b7d22a0b4d8abd/html5/thumbnails/48.jpg)
1. All study GPS devices gave “wrong message” when destination
access points were located less than 100ft from exit ramps.
2. The likelihood of WWD incidents increased significantly when
the access points were located less than 600ft from exit ramps.
This result is consistent with WWD crash data analysis.
Proven Geometric Design Elements (GPS Study)
![Page 49: Geometric Design Elements to Reduce Wrong-Way (WW) …conferences.dot.state.al.us/.../Geometric_Design.pdfProven Geometric Design Elements (WWD Crash Analysis) Non-Traversable Crossroad](https://reader035.vdocuments.site/reader035/viewer/2022071113/5fe9e09fd7b7d22a0b4d8abd/html5/thumbnails/49.jpg)
Contact Information
Dr. H. Hugo Zhou, Ph.D., P.E. Associate Professor
204 Harbert Engineering Center Department of Civil Engineering
Auburn, AL 36849-5337 Email: [email protected]
Phone: 334-844-1239 http://eng.auburn.edu/resumes/hhz0001