Update on Restricted Crossing U-Turn Intersections
Transcript of Update on Restricted Crossing U-Turn Intersections
Update on Restricted Crossing U-Turn Intersections
Joseph E. Hummer, Ph.D., P.E.
Professor and Chair, Department of Civil and Environmental Engineering
Wayne State University, Detroit, MI
And
James H. Dunlop, P.E.
Congestion Management Engineer
North Carolina Department of Transportation, Garner, NC
For WTS Connecticut
October 9, 2014
Presentation Objectives
• Introduce RCUT
• Summarize recent research and
implementation progress
• Provide guidance on where RCUT might work
• Inspire you to consider RCUT
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• A.k.a. superstreet, j-turn, restricted crossing
intersection, synchronized street
RCUT
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• Three types of RCUT intersections
– Signalized
– Stop-controlled (right)
– Merge- or yield-controlled
Variations
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Conventional intersection
32 conflict points
RCUT intersection
14 conflict points
Why the RCUT Works
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• Progression
• Perfect in both directions!
• 100% bandwidth efficiency
• Any speed!
• Any signal spacing!
Why the RCUT Works
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• Pedestrians
Why the RCUT Works
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• Does not need large ROW
• Superb access to businesses and side streets
• Easy to navigate
Why the RCUT Works
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• Invented by Kramer, late-1980s
• Developed independently in MD (1990), MI
(1994), and NC (2000)
• NC currently leads
Not the same design as
median u-turn (“Michigan Left”)
History
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• Rural, four-lane divided major road, two-lane
undivided minor road
• Large sample sizes, before-and-after,
adjustments for biases
Safety Findings
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• North Carolina study
Collision Types
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Unsignalized
Site Application – US 23/74 – Sylva NC
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NC 87 at SR 1150-Peanut Plant Road
NC 87 at US 701
• NC 87 Bypass was opened in 1997
• 60 Total Crashes and 5 Fatal Crashes in
8 Years after completion
Site Application – NC 87 at Peanut Plant Rd
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NC 87-
Peanut Plant Road
Collision Diagram
Site Application – NC 87 at Peanut Plant Rd
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Traffic signals don’t
always solve the
problem, they may
just create a
different problem!
NC 87- US 701
Collision Diagram
Site Application – NC 87 at Peanut Plant Rd
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Site Application – NC 87 at Peanut Plant Rd
Previous Solution: Build an Interchange
US 17 – Shallotte NC 16
Final Superstreet Configuration
Site Application – NC 87 at Peanut Plant Rd
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Countermeasure – Relocate leg of SR 1150 – “Superstreet”
Site Application – NC 87 at Peanut Plant Rd
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Crash Summary Table – “Superstreet - Before to After”
Before (3 Yrs)
3/1/2003-2/28/2006 Total Crashes
Crashes/
Yr
24 8.00
Total Injury
Crashes
Crashes/
Yr
21 7.00
Frontal Impact
Crashes
Crashes/
Yr
22 7.33
Frontal Impact
Injury Crashes
Crashes/
Yr
19 6.33
After (1.5 year update)
9/1/2006-2/29/2008 Total Crashes
Crashes/
Yr
2 1.33
Total Injury
Crashes
Crashes/
Yr
0 0.0
Frontal Impact
Crashes
Crashes/
Yr
1 0.67
Frontal Impact
Injury Crashes
Crashes/
Yr
0 0.00
Site Application – NC 87 at Peanut Plant Rd
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20 US 1 – Lee and Moore Counties, NC
Site Application – US 1
Crashes Injuries Fatalities
Location Before After Before After Before After
1 20 31 10 17 1
2 12 25 5 13
3 12 22 7 10
4 55 49 23 17 1
5 10 15 5 7
6 6 12 4 5 1
7 9 20 4 5
8 6 10 1 6 1
9 30 33 19 11 2
10 12 23 5 13 1
11 8 37 5 17
12 17 25 12 18 2
Totals 197 302 100 139 6 3
Results 53% Increase 39% Increase 50% Decrease
Installing Traffic Signals Crashes Injuries Fatalities
Location Before After Before After Before After
1 21 8 13 5 2
2 27 4 16 1
3 36 10 23 3
4 58 16 28 10
5 20 5 3 1
6 48 20 16 0
7 28 7 15 4
8 30 14 18 4 1 1
9-1 0 2 0 0
9-2 1 2 0 0
9-3 0 2 0 0
9-4 10 12 7 5
9-5 9 3 7 1
9-6 0 1 0 0
9-7 1 1 0 0
9-8 14 8 9 4 2 1
9-9 0 1 0 0
Totals 303 116 155 38 5 2
Results 62% Decrease 75% Decrease 60% Decrease
Installing Directional Crossovers
Directional Crossover Vs. Traffic Signal
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• Planning level
• Critical lane method
• CAP-X
• Detailed level
• VISSIM or other simulation
• Has been calibrated
• Great animation
• Macroscopic level…
Capacity Analysis
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• NCDOT study used calibrated VISSIM model to show 20% overall travel time improvement
• Field study from TX:
Metric Before RCUT After RCUT
Southbound travel time
(morning rush hour)
23.3 minutes 13.9 minutes
Southbound average speed
(morning rush hour)
16 mph 20 mph
Northbound travel time
(evening rush hour)
19.2 minutes 12.7 minutes
Northbound average speed
(evening rush hour)
19 mph 29 mph
Traffic count
(vehicles per day)
60,100 – 74,000 63,600 – 81,500
Capacity Results
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Site Application – US 15-501 Chapel Hill
24 42,000 ADT on Four-Lane Expressway – 6-Phase Split Side Street Signal
2005 TSIS-Corsim Comparison Before (Traditional Intersection) vs.
After (Superstreet Intersection) T
raditio
nal
Supers
treet
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Avg.
Speed LOS
Avg.
Speed LOS
Avg.
Speed LOS
Avg.
Speed LOS
Avg.
Speed LOS
Avg.
Speed LOS
2005 11.0 F 9.4 F 14.1 F 11.9 F 29.1 C 26.7 D
2006 27.0 C 24.0 D
2007 25.0 D 22.0 D
2008 23.0 D 21.0 D
2009 21.0 D 19.0 E
2010 29.1 C 17.9 E
2011 19.0 E 17.0 E
2012 18.7 E 15.5 F
2013 18.5 E
2014 19.3 E
2015 17.7 E
2016 18.2 E
2017 16.9 E
2018 17.1 E
2019
2020
2021
2022
2023
2024
2025
Lifespan by
Peak (years) 13 70 1 0 1
Ye
ar
"No Build" Proposed Superstreet
AM PM AM PM AM PM
Preliminary Level of Service Analysis
Site Application – US 15-501 Chapel Hill
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Site Application – US 15-501 Chapel Hill
Pedestrian Crossing Movements
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Superstreet Project Visualization - 2002
Site Application – US 15-501 Chapel Hill
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US 15-501 – Chapel Hill, NC During construction – 2007
Site Application – US 15-501 Chapel Hill
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Site Application – US 15-501 Chapel Hill
US 15-501 – Chapel Hill, NC After construction – 2010
• Capacity – Extend Life of Corridor 7-12+ years
• 60% reduction in Travel Time
• 220,000 kg Emissions Reduced Annually
Site Application – US 15-501 Chapel Hill
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• Four-lane divided expressway
corridor
• Before: no signals, little side street
traffic
• After: Large residential
developments, three commercial
centers
• Improvements paid for by three
developments in one construction
project
• 28-42% travel time savings on US 17
through movements
• Extended from 3 to 5 intersections
Site Application – US 17 Leland
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Site Application – US 17 Leland
Comparison of Superstreet and Traditional Intersection
Corridors
US 64 Cary US 17 Leland Percent
Traditional Superstreet Difference
7/1/2006-6/30/2009 +/-
Total Crash Rate 308.5 180.0 -41.7%
Total Crashes/Mile 125.1 84.8 -32.2%
Intersection Crashes 177.0 95.0 -46.3%
Total Crash Severity Index 4.6 5.0 8.2%
Fatal Injury Crashes/Mile 0.9 0.8 -11.1%
Class A Injury Crashes/Mile 1.8 0.8 -55.6%
Class B Injury Crashes/Mile 6.0 9.8 63.3%
Class C Injury Crashes/Mile 27.2 19.6 -27.9%
PDO Crashes/Mile 89.1 53.8 -39.6%
Frontal Impact Crashes/Mile 25.4 25.3 -0.4%
Rear End Crashes/Mile 80.3 40.0 -50.2%
AADT 37,000 43,000 16.2%
Intersection Density (/Mile) 3.7 3.3 n/a
Length (Miles) 2.2 1.2 n/a
Superstreet vs. Traditional Intersection Corridors
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• Analysis procedure for RCUTs
• Six types of RCUTs
• Can extend logic to other geometries
• HCS implementation
• Turning movement translator
• Key is estimation of extra travel time
• Includes control delay at all points plus time
spent traveling extra distance
Proposed HCM 2015
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• RTOR
• UTOR
• Critical headway
• Critical follow-up time
• Lane utilization
• U-turn saturation flow adjustment
• Arrival types
Considering Unique RCUT Features
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• 2013 NCDOT study
• Good ped options
• Bikes fine on main
street
• Crossing bikes
• As peds
• As vehicles
• Proposed direct link
Ped and Bike Research
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• FHWA “Every Day Counts”
• RCUT, median u-turn, displaced left turn, and DDI
• Planning, ped/bike, safety, operations, geometrics,
TCDs, construction
Informational Guide
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• Several states have developed materials
• FHWA new material
• Professional quality videos
http://www.youtube.com/watch?v=BLwl01NCp9I for the RCUT
http://www.youtube.com/watch?v=fshW_O_XggI for the MUT
http://www.youtube.com/watch?v=eLAwwl3EtN4 for the DDI
• Video "case studies" for these designs as well
• Brochures
Public Information Material
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Brochures
FHWA Brochures/Informational Guides
Presentations
Public Information Material
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Advantage Urban Rural
Safety Likely √
Progression √
Capacity √
Pedestrians √
Superstreet Advantages
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• Urban or rural
• Signalized or unsignalized
• Narrow or wide
• Peds or no peds, …
• Main restriction is light
minor street demand
• Ideal corridor treatment
RCUT Niche
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Demands, vph
EB left 480 120 60
WB left 120 60 110
NB left & th 210 310 140
SB left & th 70 90 100
1600’ 1000’ 1400’ 1300’
0.96 1.00 0.91 0.64 0.59 Conventional v/c
Proposed 8-lane divided street, downtown, 3000+ vph WB,
1500+ vph EB, heavy pedestrian crossing demand
Result: long cycle, high lost time, no EB progression
Example
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1600’ 1000’ 1400’ 1300’
0.96 0.78 0.91 0.54 0.59 Proposed v/c
RCUT at second and fourth intersections, others remain conventional
Result: Low lost time, great progression both directions,
additional signalized midblock ped crossing opportunities
Crossovers
120-sec cycle, 30 mph progression speed
Proposed Solution
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• At least consider RCUTs
• Safer
• Better traffic operations
• Good for peds
• Good for business
We Hope You’re Inspired To…
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Thank You!
• Joe Hummer
• Jim Dunlop
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