American Traffic Safety Services Association
8
The scenic Coronado Bridge, a five-lane structure rising 200 feet above the water to connect San Diego and
Coronado, is an example of how The Road Zipper was the best solution to reconfigure the bridge lanes—
and eliminate the possibility of crossover accidents.
When the bridge opened in 1969, about 11,000 vehicles per day crossed it, but by 1993 the number of vehicles
had tripled and head-on accidents were growing out of control. From 1990 to 1992, there were 21 cross-median
accidents with two fatalities. The original design had included a managed lane system to reconfigure the five
lanes multiple times a day to provide three lanes to the peak traffic direction at all times. Plastic stanchions were
placed and moved by hand to reconfigure the lanes—giving adequate delineation for drivers, but no positive
protection between traffic lanes.
Caltrans installed a concrete moveable median barrier—The Road Zipper—to help prevent crossover accidents.
This concrete, moveable median barrier was able to reconfigure the bridge lanes in the same manner as the plastic
stanchions while eliminating crossover accidents. Caltrans reported no crossover accidents since The Road
Zipper’s installation of the moveable barrier system. Another benefit has been the increased use of the center
lanes, which had been underused due to the possibility of head-on collisions.
After 18 years, Caltrans decided the system should be retired and researched new, modern options for managing the
bridge lanes. Again, The Road Zipper was still the best way to reconfigure the roadway without crossover accidents.
The new Reactive Tension barrier from Lindsay Transportation Solutions was installed on the bridge with significant
upgrades from the old system. Eighteen-inches-wide, it gives the most space possible to drivers. When impacted, the
new barrier has half the deflection of the original—from 52 inches down to 27 inches at NCHRP 350 Test Level 3.
The new Road Zipper system has a life expectancy of 20 or more years. Caltrans has invested in preventing
congestion and saving lives into 2030 and beyond on the Coronado Bridge.
The eastbound McClugage Bridge in Illinois needed major rehabilitation, meaning that the newer, westbound bridge
would have to carry two-way traffic while the older bridge was being repaired. Built in 1949, the steel through-truss
bridge needed complete replacement of the floor beams and stringers (which span the beams and support the deck)
and also repairs to the trusses above and below—a monumental job that couldn’t be done with traffic on the bridge.
The Illinois Department of Transportation (IDOT) District Four had a challenge: to place both eastbound and
westbound traffic on the adjacent, newer structure would require a positive separation of traffic, providing a
maximum of three lanes. The question for IDOT was how to best accommodate traffic—either morning or
afternoon rush hour or a scheme with reversible lanes. The decision was made to use the Quickchange Moveable
Barrier (QMB
™
), a product of Barrier Systems Inc. (Lindsay Transportation Solutions). QMB
™
is moved laterally
by a transfer machine without disrupting traffic to allow for two lanes in the direction of the rush hour traffic.
The product consists of connected, one-meter sections of safety-shaped concrete barrier with a T-shaped top to
accommodate the lifting rollers on the barrier transfer machine.
The Delaware River Port Authority (DRPA) is now operating with QMB
®
technology on the Walt Whitman,
Ben Franklin and Commodore Barry bridges, which link New Jersey and Pennsylvania in and around
Philadelphia. Moveable barriers were installed to reduce congestion and improve safety, and the project was one
of many moveable barrier sites in the Northeast Corridor.
Both the Walt Whitman and Ben Franklin bridges previously had been restricted to a maximum of six lanes with
the seventh lane used as a buffer. Paul Drayton, DRPA’s executive director said in the
Philadelphia Inquirer
,
“Effectively, we’re adding a seventh lane…it gives us tremendous flexibility. It will significantly improve traffic
flow in one of the most congested traffic areas in the region.”
In 2010, the DRPA upgraded the moveable barrier on the Walt Whitman Bridge to a Steel Reactive Tension
system that has a steel-shelled barrier only 13 inches wide and extremely low deflection characteristics.
Drivers crossing the Walt Whitman Bridge can rest assured they are even safer than before.
> > >
For more information about the The Road Zipper System™ by Lindsay Transportation Solutions,
visit
.
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