reference line – "virtual stringlines in the project coordinate
system" – a reference point and a steering offset. Similar to a
stringline, using a rectangular grid with stringless paving is
suggested, but surveying is not necessary. The project can be
modeled with as many or few details as needed for vertical,
horizontal curves, transitions and super elevations. The model
can represent existing stringline data, slab edges – i.e. "virtual
slabs" – or any arbitrary offset (position and/or height).
The future of stringless paving
Steeves says eliminating the wire line on a jobsite creates
safer working conditions for crews because they do not have
to constantly step over it or manage the gates for the truck
entrances, conventionally set up about every 600 to 800 feet.
"Wireless technology allows trucks to come in ahead of the
paver safety and back up a minimal distance," Steeves says.
Minimizing backup increases paving efﬁciency, Steeves says.
Using stringless technology increases the efﬁciency because
the contractor can start paving as soon as the subgrade is veriﬁed instead of waiting for the paving pins to be set and for
their own crews to set the stringlines. Such was the case with
the Utah 1-15 Corridor Expansion project.
Progressive contractors are more often than not asking
counties and DOTs to create 3-D digital designs of their projects to be entered into the paving machine control systems,
Steeves says. "In the future, most design work will be done
on these digital programs," he says. "The way technology is
advancing so rapidly, contractors are pushing DOTs to provide
Stringless Paving: How it works
back to total stations, giving them X, Y, Z positions.
stations to computer on the paving machine.
position in relation to a computer model of the new
each of the four corners of the pan to achieve the correct pavement thickness, crossfall (cross-slope control
monitored by sensor) and mainfall (forward and back
slope control monitored by sensor).
Smooth as glass.
Better Roads January 2014 19