Lommen Bridge, spanning new ground in rural trestle design

Lommen bridge is set to undergo a traffic-control change in order to move Miami-Foley motorists to the new bridge while the old one undergoes demolition. Aiming for July 19 to make the change.

By Brian Cameron

With construction that began work in the Fall of 2015 the span-way is now nearly to the point where it will be able to handle the loads it was designed for.

“Here in the next week we’ll begin our demolition process which will essentially move cars from the old bridge to the new bridge,” said Andy Brentano with Farline Bridge Inc.

Over the last two years the crew has carefully started the process of creating the newly designed approach ramps and panels, cross girders, parapets, deck slabs, piers and expansion joints which all go into making a new, modern structure, capable of withstanding a variety of situations including a massive subduction style earthquake.

“The Miami-Foley Road is a major lifeline for Tillamook County and a major bypass for Highway 101,” said Tillamook County Public Works Engineering Technician Gregory Cickavage. “The bridge needs to be sturdy and ready to go in the event of an unforeseen situation.”

What makes the new Lommen Bridge so unique is the inclusion of the specific technology that enables the superstructure to withstand the flexing capacities required for a subduction style earthquake. They’re called Isolation Bearings and they essentially act as large-scale shock absorbers, when the earth shakes, the bridge stands still.

In fact Lommen Bridge is only the second in the entire State of Oregon to receive such retrofitting and only a handful of bridges in the region or even the country are equipped with it.

“You’d find more technology like this on new structures in places like southern California where seismic activity is more frequent,” said Cickavage. “It was the newest technology and it seemed the way to go.”
The project was initially started during the time that Liane Welch, former Tillamook County Public Works Director, was holding the management position and according to Cickavage she pushed hard to get the project going under the idea that Tillamook County was uniquely threatened during a catastrophic earthquake and tsunami.

“One great thing about this new design is the fact that the piers are further up on shore and embedded into the riverbank,” said Brentano, Farline Bridge Inc. representative. “That means that during a flood you won’t have logs jamming up and creating a disastrous backflow problem.”

According to company representatives the project is set to complete by the end of the summer, though they did admit there was still quite a bit to do before they could call it complete. The traffic change should occur around July 19 but that date is still tentative, as a number of unforeseen issues have arisen since the last update from County Public Works.