AASHTO Subcommittee on Design MeetingJune 10, 2004

NCHRP Project 3-69

Design of Construction Work Zones on High-Speed Highways

Kevin M. MahoneyPenn State University

Project Objective

Develop a comprehensive design-decision methodology

for construction work zones on high-speed highways.

Panel

James Kladianos, WY DOTRussel Lenz, TX DOTHerbert Roy, NYS DOTRobert Schlicht, FHWAJohn Smith, MS DOT

Xiaoduan Sun, U of LAJ. Richard Young, PBSJKenneth Opiela, FHWAFrank Lisle, TRBCharles Niessner, NCHRP

Michael Christensen, Mn DOT (Retired) - Chair

Schedule

Started: August 2003

First Interim Report: March 2004

Second Interim Report: August 2005

Completion: February 2006

What we learned: from literature

1. Crash rates: generally higher in work zones than outside (studies vary)

2. Dominant work zone crash type: rear-end (same dominant type as outside of work zones)

3. Dominant work zone crash location: activity area

What we learned: from literature

Studies of design variables/decisions effect on safety:

• Work zone length: number of crashes increases with length

• Reduction of lane width: crash rates increase

• Diversion strategy: small effect on crash rates

• Freeway entrance ramp: effect of ramps not found; accel lane elimination or significant reduction may have negative effect

What we learned: from survey of state DOTs

1. Current practice: substance and variety

2. Priorities for research and guidance development under this project

State DOT Priorities

• Bridge width

• Clear zone *

• Cross slope rollover

• Horizontal clearance

• Median slope

• Normal cross slope

• Normal shoulder slope

• Traveled way width *• Shoulder type

• Shoulder width

• Sideslope

Scope of design-decision methodology: Cross Section

Scope of design-decision methodology: Horizontal Alignment

• Compound curve ratio

• Radius of curve *

• Superelevation

• Superelevation transition

Scope of design-decision methodology: Vertical Alignment

• Critical length of grade

• Maximum grade

• Minimum grade

• Vertical curve

Scope of design-decision methodology: Other

• Barrier placement *

• Contractor traffic control plans *

• Design speed *

• Decision sight distance

• Stopping sight distance *

Development Methodology: Ideal

Expected:• Safety• Mobility

Performance Model

Prevailing conditions

Design variables

Development Methodology: Realistic

Candidate Focused Studies

• Statistical analysis of median crossover radii and paved roadway width

• Work zone speed profile model• Performance of heavy trucks in work zones• Roadside design and barrier placement guidance• Influence of design features on driver performance • Analyzing work zones using microsimulation

TYPICAL APPLICATION 34 (SAMPLE OUTPUT)

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

DISTANCE

SP

EE

D (

MP

H)

LANE A

LANE B

C AB L

Sample ANN output for speed profile model

Recovery distance (feet)

Di r

ect i

onal

Tra

ffic

Vol

ume

(tho

usan

ds p

er d

ay)

Barrier StudyWarranted

Barrier Recommended

Barrier Study Optional

Possible format for roadside barrier placement design guidance

Challenges

Performance measures

Data• Median crossover, radii and paved roadway width• Crash locations while crossover in place

QUESTIONS?