"Get In, Get Out, and Stay Out"
Editorial by Cliff Freyermuth, Manager, ASBI
The title of this editorial is a short form of an AASHTO goal or mission of reducing project construction time and reducing the need for project maintenance activities following construction. As part of this effort, AASHTO has established a Technology Implementation Group (TIG) Implementation Panel on “Prefabricated Bridge Elements and Systems.” The Chairperson of this TIG Implementation Panel is Mary Lou Ralls, P.E., State Bridge Engineer, Texas Department of Transportation.
To illustrate the speed of construction advantages for precast segmental bridges, this edition of the newsletter includes project reports on the “Big I Interchange” in Albuquerque by Jimmy D. Camp, P.E., New Mexico State Bridge Engineer, and the “Spaghetti Bowl Interchange” in Las Vegas by William C. Crawford, Jr., Chief Bridge Engineer, Nevada Department of Transportation. In both cases, these were the first precast segmental projects in these states. Both projects were very successful in reducing construction time and the related inconvenience to the traveling public. Segmental construction was also considered to be cost competitive, and to offer aesthetic advantages for these projects.
The AASHTO-PCI-ASBI Standard Segments for bridge spans of 100 to 200 ft make the construction speed advantages of precast segmental construction economically accessible for smaller bridge projects. These segments are now being used in the construction of the Ft. Lauderdale-Hollywood International Airport Interchange in Florida designed by Beiswenger Hoch and Associates, Inc. (a large project containing 551 segments). As an example of use of precast segmental construction for smaller projects, the Whitehurst Freeway Ramp in Washington D.C., designed by Figg Engineering Group, was selected as a Value Engineering option after the bid at a lower cost than the original bid. The Whitehurst Freeway Ramp is only 744 ft. long, and it was erected over three busy urban streets with minimal traffic disruption.
In regard to the “Stay Out” aspect of the AASHTO goal, there are no segmental bridges included in the NBI listing of deficient bridges in the U.S. The NBI data shows that significant percentages of bridges constructed with other materials or methods 20 years of age (or less) are listed as deficient. There are considered to be no bridge construction alternatives available with conventional cast-in-place concrete decks that provide the deck durability advantages of longitudinal and transverse prestressing, as well as the reduced construction time achievable with precast segmental construction