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Within a very tight schedules, a

1.5 km of bridge parapets had

to be constructed, but, using

advanced equipment, this was

no problem for the Sangamo

Construction Company.

Stringless

Construction

Of Parapets

Based in Springfield, Illinois,

Sangamo Construction

had

been contracted to build several bridges including the

parapets required: five bridges in central Illinois with a

combined length of some 850 m plus another 700 m in

the southern part of the state.

The parapets were 1 m high, 48 cm thick at the bot-

tom, tapering to a width of just under 27 cm at the top,

and had a perpendicular rear wall. As much as 260 m

3

of concrete were processed just for the construction of

the four 150 m long parapets on the twin bridges on

Interstate Highway 55 near the small town of Lincoln.

The paving work was performed by a

Wirtgen

Slipform Paver

SP 15i with AutoPilot which Sangamo

had purchased from the North American Wirtgen Group

along with an extra mould for parapets and another for

curb and gutter profiles.

“We have been in the concrete construction

business for a long time and are particularly

experienced in the field of

bridge construction,”

reports John

Jilg, Project

Manager at

the Sangamo

Construction

Company.

In the past,

a small team

constructed the sidewalks, curbs and gutters and then

Sangamo concluded 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 a slipform paver,”

“The three crawler tracks and the possibil-

ity of mounting the moulds on either side of the

machine are huge benefits,”

explains the Project Manager.

He felt that a larger model with four crawler tracks

would not have been the right choice, particularly for

work on narrow roads, which are often obstructed by

parked cars in urban areas. This would disrupt the flow

of traffic too much. 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 1 m high parapets,” adds Jilg.

Stringline-Free Paving Technology

The possibility of stringline-free paving was another key

aspect in plant selection Developed by Wirtgen, the

AutoPilot is a 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 based system ensures maximum precision

and efficiency, not only when creating straight or com-

plex curved concrete profiles,

but also when constructing

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 600

mm. The time-consuming and

labour-intensive surveying, in-

stallation and removal of string-

lines can now be completely

dispensed with.

Sangamo Construction Co

Wirtgen America

Contractors World International Vol 7 No 3

19

Contractors World International