IRRIGATION & INTERSECTION AMENDMENTS

Wollam Construction installed Utah’s first mechanical runaway truck escape ramp on U.S. 89 in Logan Canyon, below the final grade prior to entering Garden City. The truck escape ramp uses an innovative design with a concrete chute to guide runaway trucks into cable restraints. When the runaway truck hits the cable net system, the nets will wrap around the vehicle, initiating a controlled deceleration and stop. It is the first ramp of its kind in Utah.

date
October 2020
location
Garden City, Utah
client
Utah Department of Transportation

PROJECT OVERVIEW

project brief

This vehicle arresting barrier (VAB) is first of its kind in bringing errant vehicles to a safe, controlled stop as they impact a series of energy absorbing nets that are strategically located along its length. This system incorporates three primary new design improvements that serve to overcome the challenges posed by existing vehicle arresting technologies.

The first design improvement is the use of innovative tapered throat sections that occur at multiple locations along the length of the VAB. These sections were formed by the barrier’s walls and served to continuously “choke” the errant vehicle toward the middle of the VAB. They ensure that errant vehicles properly engage each net in the most efficient manner, serve to protect the energy absorbing mechanisms from a direct impact, and serve to maximize safety and stability of the errant vehicle as it traverses the VAB.

The second design improvement is a new connection for the net’s energy absorber housings. This connection allows the energy absorber to follow the net in both the vertical and horizontal plane as the errant vehicle traverses the VAB. In addition, this connection limits the initial shock load applied immediately upon impact by an errant vehicle.

The third design improvement incorporates a heavy-duty, high-force energy absorbing net that is located at the end of the trap. The design features inset pockets, each located on the sides of the VAB’s concrete walls, that house high-force energy absorbing units. These units consume an errant vehicle’s energy through the deformation of a 50 ft long stainless-steel flat bar that is housed in a tube located inside of the concrete walls. When an errant vehicle impacts the heavy-duty net, these stainless-steel flat bars are pulled out of the wall tubes, through the high-force energy absorbing units and bring the vehicle to a complete stop.

deliverables
  • Heavy Civil
  • Underground Utilities
  • Concrete

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