September 20th, 2011
BREAK AWAYUncategorized, by Catherine Higgins.
A project to install new welcome signs around the state also gave UDOT a chance to use a new sign base.
Welcome to Utah signs placed last year feature Utah attractions and a breakaway type base that’s new to UDOT. A similar design has been used successfully in Idaho and other states for many years. The signs were placed in or near clear zones on interstates and at Utah Welcome Centers.
Clear zones are designed to allow errant vehicles a place to safely stop or re-gain control. Signs that are installed in the clear zone are required by the Manual on Uniform Traffic Control Devices to be protected by a crash cushion or have a breakaway design – that is, in a crash, the sign post should break away from the base and go over or under the vehicle.
It’s long been known that breakaway signs are safer for drivers than rigid signs. In 1963, the Texas Highway Department, the Texas Transportation Institute and the U.S. Bureau of Public Roads cooperated when “Substantial miles of the Interstate System was under construction or scheduled for construction” and the need for safer sign supports was imperative. New sign bases were designed, tested and put into use. (Highway Research Record #174, Guardrails, Barriers and Sign Supports)
This interactive timeline on the TTI website shows that crash testing on breakaway sign bases was conducted at their facility in 1964, and the first known life saved as a result of a breakaway sign base was documented in 1965.
The new sign base has been tested according to Federal requirements, but UDOT Traffic and Safety wondered how well the sign base would hold over time. Since the signs are placed throughout the state and subject to all kinds of weather, the welcome sign project provided a good chance to find out how the base performs in high winds or heavy snow – so far, the sign bases are working well.
The posts on new base are secured to footings using couplings that break away in a crash leaving a very short stub. Joints on the posts also cause the sign to fold on impact. The design limits property damage to the road user and UDOT. After the base is damaged, repair is simple and inexpensive; posts can be re-bolted using conventional tools. “It is a matter of changing the hinge plates on the posts and couplings on the ground,” according to Customer Services Representative for the vendor. Because of the design, “usually the posts do not need to be replaced.”
Dave Skinner, Road Operations Coordinator in Region Three near the Wyoming State Line sees all kinds of extreme weather. “You name it… cold, snow, rain, and very high wind,” he says. High winds regularly damage signs in his area. “Last year, the wind got a whole bunch of them,” he reports. But the new sign base has held up under daily windy conditions that range between 20 and 50 mph.
UDOT Traffic and Safety is looking forward to working with the UDOT Regions to identify other appropriate places to use the new sign bases.