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 'Sequential Warning Light System for Work Zone Lane Closures' PowerPoint Presentation

Slide 01

Title: Sequential Warning Light System for Work Zone Lane Closures

by Melisa Finley, Gerald Ullman, & Conrad Dudek for the

Making Work Zones Work Better Workshop

From the Texas Transportation Institute

Transportation Operations Group

Slide 02

Title: Background

  • Individual flashing warning lights.
    • The 2000 MUTCD states "Flashing warning lights shall not be used for delineation, as a series of flashers fails to identify the desired vehicle path."
    • Sequential flashing warning lights.
  • Series of synchronized flashers
  • Used in Europe

Slide 03

Title: Purpose

To reduce the chance of vehicles running into a work zone lane closure
at night by increasing conspicuity and by increasing location and direction information at the closure taper


Slide 04

Title: Warning Light System

Photo of a road at night-time of traffic cones with lit with LED lights and lined along the road shoulder.

Slide 05

Title: Warning Light System

  • Wireless
  • Radio controlled
  • Up to 16 lights
  • Up to 80 ft apart
  • Components
    • LED warning light
    • Transmitter-receiver case

Slide 06

Title: Research Plan

  • Closed-course
    • Motorist comprehension
    • Earlier lane-changing
  • Field
    • Operational effects
    • Safety benefits

Slide 07

Title: Closed-Course Studies

  • Nighttime
  • 59 subjects
  • Motorist performance
  • Motorist preference

Slide 08

Title: System Designs

  • No-light background
  • Steady-burn light background

Slide 09

Title: Treatments

  • No lights
  • Steady-burn lights
  • Steady-burn light background system w/ 60 fpm
  • No-light background system w/ 17 fpm
  • No-light background system w/ 60 fpm

Slide 10

Title: Comparison of Treatments

Diagram: This graphic compares the percentage of subjects that found treatments helpful vs. those that found them confusing, displayed for each of four treatments.

  • For the first treatment Steady-Burn, 68 percent found it helpful, while 4 percent found it confusing.
  • For the second treatment Steady-Burn with 60 fpm, 79 percent found it helpful, while 10 percent found it confusing.
  • For the third treatment No-Light with 17 fpm, 56 percent found it helpful, while 29 percent found it confusing.
  • For the fourth treatment is No-Light with 60 fpm, 45 percent found it helpful, while 34 percent found it confusing.

Slide 11

Title: Motorist Preferences

Diagram: This graphic is a pie chart comparing four motorist preferences. The Steady-Burn Light Background System was preferred by 42%. The No Light Background Systems were preferred by 20%. The Steady-Burn Lights were preferred by 16%. No Warning Lights were preferred by 22%.

Slide 12

Title: Field Studies

  • Nighttime
  • Treatments
    • No lights
    • Steady-burn light background system
  • Measures of performance
    • Speeds
    • Lane choice & erratic maneuvers

Slide 13

Title: Sites

Site 1

  • Rural
  • Low volume
  • 65 mph
  • 2 lanes ® 1 lane
  • Closure 6 months old

Site 2

  • Urban
  • High volume
  • 65 mph/55 mph
  • 3 lanes ® 1 lane
  • New closure

Slide 14

Title: Results (part 1 of 2)

  • No effect on speed
  • No effect on erratic maneuvers
  • No effect on lane choice at Site 1
  • Did effect lane choice at Site 2

% of vehicles in closed lane lower with system

Slide 15

Title: Results (part 2 of 2)

Diagram: This graphic compares the percentage of Vehicles in Closed Lane 1000 feet from Taper with and without a system. The vehicles are divided into Passenger and Commercial categories.

In the case of Passenger Vehicles the result is 30 percent without the system and 23 percent with the system.

In the case of Commercial Vehicles the result is 19 percent without the system and 7 percent with the system.

Slide 16

Title: Implementation

  • Not justifiable in all cases
  • Greatest potential safety benefit
    • Short duration or intermediate-term projects
    • Low number of familiar drivers
    • Concerns about nighttime path guidance & visual clutter

Slide 17

Title: Example of Use

  • US 59 west of Houston
  • 3 month project
  • Converting existing mainlane shoulders to auxiliary lanes between access ramps
  • Majority of work at night
  • Lane closure locations change nightly

Slide 18

Title: Keep in Mind

  • Still an experimental device
  • Approval for experimentation must be granted by the FHWA
  • Section 1A.10 of the MUTCD outlines the necessary steps to apply for experimentation

Slide 19

Title: Questions?

Photo: of traffic cones in the later afternoon

Slide 20

Title: Contact Information

Melisa Finley, TTI

Jim Kennedy, Empco-Lite
800-548-5483 or 847-931-2455

Office of Operations