TULSA, Oklahoma -- The Oklahoma Department of Transportation is installing a new type of structure to support signs on major highways around the state.
They're called monotubes. As the name implies, monotubes utilize one large steel tube to suspend signs over the roadway, instead of the old truss-type structures that have been used for decades.
ODOT installed the first monotubes in the state on I-35 in Norman in 2009. Right now they're being installed at I-44 and 193rd Street in Tulsa/Catoosa, along I-44 from Riverside to Harvard in Tulsa and on the new I-40 Crosstown in Oklahoma City.
They offer numerous advantages over the older structures. Because each monotube consists of multiple smaller sections of pipe that are bolted together at the job site, they're easier to transport and can be hauled by a pickup pulling a small trailer. ODOT says they're also relatively easy to install.
ODOT spokeswoman Kenna Mitchell said monotube structures also do not require as much maintenance, are more wind-resistant and -- possibly the biggest advantage of all -- are much harder to vandalize because they're practically impossible to climb.
Mitchell says the monotubes installed in Norman last year were built by a company in Missouri. "Other manufacturers are Pelco Structural in Claremore and Ziese Manufacturing in Oklahoma City," she said.
The transportation departments in Arizona, New Mexico and Colorado have been using them for years. Mitchell said ODOT conducted a lengthy review process then adopted a set of standards for monotube structures here in Oklahoma.
According to ODOT monotubes cost about the same as the old style. There are 550 of the old truss-style structures around the state. ODOT has no plans to replace them all, but it will switch to monotubes on any new roadway construction as the project permits.