Wirtgen Slipform Paver SP 15i with AutoPilot 3D control
Stringline-free paving for bridge parapets
Winter was coming in the northern US state of Illinois and Sangamo Construction had to build 1.5km of bridge parapets just before the end of the construction season.
Sangamo Construction was contracted to work on five bridges where some parapets needed to be 1m high x 48cm thick at the bottom, tapering to a width of just under 27cm at the top, and with a perpendicular rear wall.
As much as 26m3 of concrete were processed just for the construction of the four 150m-long parapets on the twin bridges on Interstate Highway 55 near the small town of Lincoln.
To accomplish the stringline-free construction of the monolithic profiles Sangamo used a
In the past, a small team constructed the sidewalks, curbs and gutters. But then Sangamo won a contract for a number of smaller repair jobs in urban areas. "Once we knew that we would be carrying out these tasks in addition to our bridge construction work – which always includes safety barriers in the form of bridge parapets – we decided to purchase an offset slipform paver," said Jilg.
The smallest model in Wirtgen's concrete paver fleet was best, he explained, because of its flexible range of applications. "The three crawler tracks and the possibility of mounting the molds on either side of the machine are huge benefits."
A larger model with four crawler tracks would not have been ideal for Sangamo’s work which is mainly on narrow urban roads obstructed by parked cars. But with its SP 15i, Sangamo is always flexible. "We have used the slipform paver to construct curbs and gutters in Springfield, but we can also use it to build 1m-high parapets," said Jilg.
The possibility of stringline-free paving was another key aspect. Developed by Wirtgen, the AutoPilot is a user-friendly, cost-effective 3D control system for offset applications and the construction of monolithic profiles such as concrete safety barriers, curbs, gutters and channels. The GPS ensures maximum precision and efficiency for creating straight or complex curved concrete profiles and closed configurations. There is no need for a digital terrain model, as the profile path or configuration is programmed on the spot.
The AutoPilot permits fully automated top-quality paving in radii down to as small as 600mm, and without stringlines, now a thing of the past for Sangamo.
