vdot’s work zone research and practices

VDOT’s Work Zone Research and Practices

Ben CottrellVirginia DOT Research Council

ASSESSMENT OF ADVANCED WARNING SIGNS FOR

FLAGGING OPERATIONS

Steve Jones

Ben Cottrell

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.

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.

• 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.

Background (cont.)

• 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.

Purpose

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

Methodology

• 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

Identification of Participants & Mailing of Survey

Survey Statistics

• 3,600 delivered• 1,383 replies including 20 via web site

– 759 existing sign– 624 proposed sign

• 38% return rate

• 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

Response Codes

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

Existing Sign

no22.4%

yes77.6%

Proposed Sign

no35.2%

yes64.8%

Survey Question 2What do you think the sign means?

Existing Signsubst. correct22.3%

correct76.5%

Proposed Sign

subst. correct23.9%

incorr27.5% correct

52.3%

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

Existing Sign

correct96.4%

Proposed Sign

correct91.4%

.

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

driving?

Existing Sign

correct65.6%

substant. correct32.4%

incorrect2.0%

Proposed Sign incorrect4.2%

correct78.7%

substant correct17.1%

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

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.

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.

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

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

IMPROVING NIGHT WORK ZONE TRAFFIC CONTROL

Why Night Work?

Worker Safety

Motorists’ Safety

• 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.

METHODS

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

Traffic Control Problems

State DOTsState DOTs• Poor visibility• Impaired drivers• Higher speeds and

lower volume• Insufficient lighting

VDOT ResidenciesVDOT Residencies• Poor visibility• Higher average

speed• Motorists inattention• Inadequate lighting

Solutions

State DOTsState DOTs• Improve visibility of

workers• Use drums in taper• Detail lighting plan• Use police• Maintain devices

VDOT ResidenciesVDOT Residencies• Use police• Specify lighting

requirements• Use drums• Use heavier cones

CONCLUSIONS

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

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.

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.

RECOMMENDATIONS

• Improving Visibility of Traffic Control Devices

• Worker and Work Vehicle Visibility• Managing Traffic

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.

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.

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.

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.

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.

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.

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  

VDOT Work Area Protection Manual and Practices

Focus

• Highlight some areas where VDOT exceeds MUTCD.

• Traffic control and safety.• Tools, training and public awareness.

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.

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.

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.

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.

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.

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

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

Public Awareness Campaign

• VDOT Internet site:http://virginiadot.org/comtravel/eoc/eoc-main.asp.

• Special Internet site for major projects.• Regular daily feature in local

newspapers and radio stations identifying work zones.

QUESTIONS?