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

4

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

6

• Pedestrians

Why the RCUT Works

7

• 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

10

• 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

joseph.hummer@wayne.edu

• Jim Dunlop

jdunlop@ncdot.gov

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