The image is familiar from countless cowboy films. Early pioneers travelled west across the USA, following the route through the Platte River Valley in Nebraska, in trains of covered wagons to set up homesteads on unclaimed land. Those journeys have now been commemorated with the erection of the Great Platte River Road Archway Monument over Interstate 80 at Kearney, Nebraska.
The $60m project was funded by municipal revenue bonds which sold out in less than three hours when offered in June 1998.
The monument is a covered steel bridge – Madison County style – which spans 100m and weighs 1,500t. The bridge was prefabricated alongside the highway by Kiewit Construction between March and August and was lifted in during a 10pm to 7am closure of the highway on 16/17 August. During the closure, traffic was diverted through Kearney.
The Archway Monument was moved across I-80 on a 72-axle self-propelled modular transporter (SPMT), featuring 288 double width tyres and remote-controlled, omni-directional steering. The transporter was supplied by Davenport Mammoet.
Kiewit began by hydraulically jacking the bridge 6.7m and resting it on temporary cribbing and a horizontal jacking beam. It was then jacked horizontally onto the SPMT. Kiewit engineers designed the jacking system that ratcheted the monument horizontally from its cribbing onto the transporter.
Weeks of planning and testing were required to ensure everything went to plan on the big night.
It took two hours to drive the transporter across the highway. They were then connected to pavilion buildings on either side of the highway.
When the Great Platte River Road Archway Monument opens next April, it will house two floors of interactive exhibits about one of the most celebrated human migrations in history – the pioneers who travelled west, guided by the Platte River Valley.
