Give Workers a Brake

Can variable-message signs control speed through work zones?

by Jim LaFontaine, Dufferin Construction Company, and
Jim Zaichkowski, P.Eng., Project Coordinator, CSAO

 

Recent years have seen a tragic increase in deaths and injuries to construction workers on highway projects.

Along with other initiatives, CSAO has funded a study to determine how effectively portable variable-message signs (PVMSs) can control traffic speeds through highway work zones.

CSAO’s Jim Zaichkowski has been working with the Ontario Road Builders’ Association (ORBA) to line up highway project sites around the province.

To be useful for the study, a site must have

• a traffic protection plan that remains in place and unchanged for at least three weeks
• traffic lanes that are narrowed, or one lane that is closed, to accommodate the work under way
• a problem with traffic speeding through the zone.

It’s preferable, though not necessary, that the site also have the work zone speed reduced from the normally posted speed.

One site being used for the study is Dufferin Construction’s bridge rehabilitation project on Highway 416 near Kemptville, where northbound lanes are reduced from two to one and speed from 100 km/h to 80 km/h.

 

“Three-phase testing will help determine protective measures.”

The first phase of testing involves regular traffic control signage with no additional PVMSs. Data collectors are set out at various locations on the highway surface. Traffic speed data is collected for use as a baseline against which the effectiveness of the PVMS will be measured.

In the second phase of testing, a PVMS is set up near the reduced-speed zone. The two-part flashing message consists of HIGHWAY WORK ZONE and 80 km/h. Each message illuminates for two seconds. The messages cycle 24/7 through the test period.

For the third and final phase of testing, the PVMS is equipped with a radar detection system to activate a change in the message displayed.

When the system detects a vehicle travelling 8 km/h or more above the reduced speed limit, the message changes to MAXIMUM 80 km/h and continues to repeat at one-second intervals until the vehicle slows down.

The study would be impossible without cooperation from the Ministry of Transportation, the Ontario Road Builders’ Association, Dufferin Construction Company, and the Ontario Provincial Police. CSAO would also like to thank Battlefield Equipment Rentals for the Ver-Mac PVMSs, and Lecol Company Limited, distributor of the Hi-Star NC-97 data collectors, for substantial technical assistance.

Results from the first two test sites will be released in 2003. Jim Zaichkowski is interested in locating additional sites for testing: 416-679-4052 or jimza@csao.org.