Work Zone Mobility and Safety Program
Photo collage: temporary lane closure, road marking installation, cone with mounted warning light, and drum separated work zones.
Office of Operations 21st Century Operations Using 21st Century Technologies

Text from 'VDOT’s Work Zone Research and Practices' PowerPoint Presentation

Workshops > Innovative Technology

Slide 1

VDOT’s Work Zone Research and Practices

Ben Cottrell
Virginia DOT Research Council

Slide 2

Assessment of Advanced Warning Signs for Flagging Operations

Steve Jones

Ben Cottrell

Slide 3

Introduction

In 1983, MUTCD was revised to specify use of STOP/SLOW paddle as primary hand-signaling device.
Paddle has been the standard since 1987.

Slide 4

Background

ATSSA asked FHWA to adopt proposed sign.
In 1987, the two signs were included in ongoing FHWA human factors study using a driver simulator.
Study concluded that proposed sign was not understood by drivers, and request was denied.

Slide 5

Background (cont.)

Paddle gained acceptance, and its use increased in work zone traffic control.
Existing sign is not an accurate representation of traffic situation encountered by drivers.

Slide 6

Purpose

To evaluate ability of current and proposed sign to convey its intended message.
To satisfy FHWA requirement of a human factors study on understanding and acceptance of proposed sign.

Slide 7

Methodology

  • Literature review
  • Development of survey questionnaire
  • Identification of participants
  • Mailing of survey
  • Analysis of survey results
  • Development of conclusions

Slide 8

Identification of Participants & Mailing of Survey

Sample groups chosen (open ended)
Younger drivers in driver’s education classes
Older (> 50) drivers at local senior center

Survey mailed (multiple choice)
Addresses randomly selected from Internet phone books
4,500 questionnaires mailed out

Slide 9

Survey Statistics

  • 3,600 delivered
  • 1,383 replies including 20 via web site
  • 759 existing sign
  • 624 proposed sign
  • 38% return rate

Slide 10

Response Codes

  • Correct - implies clear understanding of intended sign meaning
  • Substantially correct - implies substantive understanding of intended sign meaning
  • Incorrect - implies total lack of understanding of intended sign meaning

Slide 11

Survey Question 1 Have you ever seen this sign in Virginia?

Pie Chart: Existing Sign Yes=77.6% and No=22.4%

Pie Chart: Proposed Sign Yes=64.8% and No=35.2%

Slide 12

Survey Question 2: What do you think the sign means?

Pie Chart: Existing Sign -Subst.Correct=22.3% and Correct=76.5%

Pie Chart: Proposed Sign -incorr=27.5.% , subst. correct=23.9%, and correct=52.3%

Slide 13

Survey Question 3 Where would you expect to see this sign?

Pie Chart: Existing Sign -Subst.Correct=96.4%

Pie Chart: Proposed Sign -Correct=91.4%

Slide 14

Survey Question 4 What would you do if you saw the sign while driving?

Pie Chart: Existing Sign -Subst.Correct=32.4%, incorrect=2.0%, and correct=65.6%

Pie Chart: Proposed Sign -Subst.Correct=17.1%, incorrect=4.2%, and correct=78.7%

Slide 15

Study Limitations

  • Survey approach
  • Survey Language
    • "flagger" versus traffic control person
    • influence of stop sign symbol
    • similarity in choices
    • sign meaning and driver behavior

Single sign versus sign series

Slide 16

Conclusions

  • The proposed sign accurately symbolizes what motorists will see.
  • The correct meaning of the existing sign was clearer to more respondents than the proposed sign.
  • Designation of "flagger" as the only correct response was biased in favor of the existing sign.
  • "Stop ahead" as an incorrect response was considered debatable.

Slide 17

Conclusions (cont.)

  • More respondents associated the desired driving behavior with the proposed sign than the existing sign.
  • Asking what drivers would do when they see a sign is a better measure than asking what the sign means.
  • The proposed sign performs as good as if not better than the existing sign.

Slide 18

Recommendations

The Traffic Engineering Division should seek FHWA approval to modify the Virginia Work Area Protection Manual to allow the use of the proposed sign.

VDOT, in cooperation with other state DOTs and national groups, should request that the FHWA modify the MUTCD to allow the use of the proposed sign.

STATUS: Under Review by FHWA

Slide 19

For more information:

Research Brief
http://virginiadot.org/VTRC/briefs/00-r8rb/night_work_zone_flash.htm

Final Report http://virginiadot.org/VTRC/main/online_reports/pdf/00-r8.pdf

Slide 20

Improving Night Work Zone Traffic Control

Slide 21

Why Night Work?

Photo of workzone at night

Slide 22

Worker Safety

Photo of workzone

Slide 23

Motorists’ Safety

Photo showing orange cones around an open grate

Slide 24

The objective: to examine traffic control for night work zones from the perspective of both worker and motorist.
Approach: investigate practices of other state DOTs, identify the problems associated with traffic control for night work zones, and potential strategies to resolve them.

Slide 25

Methods

  • Literature Review
  • Survey of State DOTs
  • Survey of VDOT Residencies
  • Review of Night Work Zones
  • Motorists Survey
  • Inventory of Strategies for Improvement

Slide 26

Traffic Control Problems

  • State DOTs
  • Poor visibility
  • Impaired drivers
  • Higher speeds and lower volume
  • Insufficient lighting
  • VDOT Residencies
  • Poor visibility
  • Higher average speed
  • Motorists inattention
  • Inadequate lighting

Slide 27

Solutions

  • State DOTs
  • Improve visibility of workers
  • Use drums in taper
  • Detail lighting plan
  • Use police
  • Maintain devices
  • VDOT Residencies
  • Use police
  • Specify lighting requirements
  • Use drums
  • Use heavier cones

Slide 28

Conclusions

  • Reduced visibility, driver impairment or inattention, inadequate lighting, and lack of maintenance of traffic control devices are common problems.

Slide 29

Conclusions

  • Traffic control for night work zones, in general, is adequate. Common problem areas: properly establishing work zones, maintaining the traffic control devices, and proper aiming and alignment of lighting to avoid glare.

Slide 30

Conclusions

  • Despite the perception that night work zones are less safe, evidence for this was not available. Based on a limited amount of data, there was no evidence of the perceived higher speeds at night.

Slide 31

Recommendations

  • Improving Visibility of Traffic Control Devices
  • Worker and Work Vehicle Visibility
  • Managing Traffic

Slide 32

Improving Visibility of Traffic Control Devices

  • Drums should be used in the transition area for lane closures.
  • Consider requiring the contractor to have full-time traffic control staff. This staff and VDOT staff should ensure that the traffic control complies with the VWAPM, work lights are not creating glare and work vehicle lights are not a distraction.

Slide 33

Improving Visibility of Traffic Control Devices

  • Under conditions of limited sight distance, the transition area should be shifted upstream to improve the visibility of the taper. Similarly, when a lane closure merge point is near an entry ramp, the transition area should be shifted upstream to separate the two merge points.

Slide 34

Worker and Work Vehicle Visibility

  • All workers should wear hard hats that have retroreflective material that is visible from all sides.
  • Ways to make retroreflective clothing visible through the full range of body motions should be considered.
  • The NY DOT guidelines for use of work vehicle flashing and warning lights should be used.

Slide 35

Managing Traffic

  • PCMS messages should be appropriate for the road conditions present. A PCMS should be considered for end-of-queue warnings in the early hours when traffic volumes may result in queues and as special attention getters later at night.

Slide 36

Managing Traffic

  • When appropriate, the message "TROOPER ON SITE, SPEED LIMIT ENFORCED" should be used. The use of radar controlled PCMS should be considered as a countermeasure for speeding.
  • The police vehicle should be positioned to maximize its visibility.

Slide 37

Implementation Plan

  • Recommendations should be presented to the Work Zone Safety roundtable for review, revisions, and implementation.
  • Employee Safety and Health Division should have lead responsibility in the areas of worker safety clothing such as hard hats.

Slide 38

For more information:

Research Brief
http://virginiadot.org/VTRC/briefs/00-r8rb/night_work_zone_flash.htm
 
Final Report http://virginiadot.org/VTRC/main/online_reports/pdf/00-r8.pdf

Slide 39

VDOT Work Area Protection Manual and Practices

Slide 40

Focus

  • Highlight some areas where VDOT exceeds MUTCD.
  • Traffic control and safety.
  • Tools, training and public awareness.

Slide 41

Cones and Signs

  • standard size cone is 36 in.
  • warning signs
  • 48 in. standard size
  • Fluorescent orange prismatic sheeting

One size only minimize errors in size and simplifies inventory.

Slide 42

Pavement Markings

  • Objective: to have pavement markings as good as or better than the original markings.
  • Use a lot temporary tape.
  • Raised pavement markers used in transition area.

Slide 43

Lane Closures

  • Extensive use of Truck Mounted Attenuators
    • TMAs shall be used on multilane highways with speed limit >45 mph
    • VDOT has >500 TMAs; contractors have 500-800 TMAs.
    • Use two additional signs not in MUTCD: Lane ends and Keep Left/Right.

Slide 44

This diagram shows the progression of road signage as traffic approaches a workzone. The signs read 'Road Work Ahead', 'Right Lane Closed', 'Lane Ends Merge Left', and 'Merge Left' as traffic approaches the orange cones.

Slide 45

Portable Changeable Message Signs

  • Extensive use of PCMSs for lane closures and lane shifts especially when queues are expected.
  • Experimenting with 12 small PCMSs mounted on pick up and dump trucks for pavement marking and environmental operations.

Slide 46

State Police in Work Zones

  • Used in just about any interstate work zones especially in urbanized areas.
  • Used on some primary and major secondary routes with high speeds.
  • Police actively pursue speeders.

Slide 47

Work Zone Safety Tools

  • Work Zone Safety Pocket Guide
  • Work Zone Safety Checklist
  • Two page carbonless four copy form or electronic copy
  • Completed by district safety officers during reviews and weekly by inspectors
  • District Safety Officers have video recording system tied to DMI in vehicles

Slide 48

Training

  • Flagger Certification
  • Now: self administered program on videotape
  • By late summer: PC based testing at local DMV with photo id card
  • Work Zone Training with VRTBA
  • 1 day course; 6-8/yr
  • 300-400 Contractor and VDOT staff /yr

Slide 49

Public Awareness Campaign

Slide 50

Questions?
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