|
Austrian
hydrodemolition specialist contractor Röhsler & Co is using an Aqua Cutter
HVD-6000 to remove more than 300 m³ of concrete to expose rebar for
installation of new impact barriers on a 300 m elevated live highway in Vienna.
Vienna’s
North Bridge
is considered to be one of the busiest bridges in Central Europe
with approximately 100,000 vehicles a day.
Much
of this traffic, from the northern suburbs, is causing major traffic congestion
with more than 42,000 vehicles daily using the A22 junction in the area of the
city’s B7, B3 and Brünner Strasse in the suburb of Floridsdorf.
As
a result construction is underway constructing an elevated 1.2 km extension of
the A22 at Prager Strasse to alleviate the heavy traffic away from the suburb
centre and improve access to the nearby shopping centre and industrial area.
Construction
work started on the new extension project by German contractor Dywidag at the
beginning of the year in a 20-month contract and a contract value of €100
million.
As
part of the project, the opportunity was taken by the city’s Highway Authority
to upgrade the impact barriers along the existing 300 m long elevated section of
the A22.
Hydrodemolition
techniques were the specified preferred option to expose the bridge rebar by the
contractor with Austrian specialist Röhsler & Co appointed as the main
sub-contractor responsible for the work.
Röhsler
& Co opted to use its HVD-6000 Aqua Cutter to cut an 80 cm wide channel to a
depth of 25 cm to expose the rebar, removing all the concrete along the outer
edge of the highway platform.
Using
a high pressure jet of water, the diesel-powered Aqua Cutter robot ‘blasts’
the concrete without causing any damage to the structure or the reinforcement
bars.
In
a second adjacent cut, Röhsler & Co prepared a further channel 1 m x 5 cm
to expose the top rebar without causing any damage.
New rebar was then embedded into the 1 m section and across to the new
extended bridge edge, further reinforcing the exposed rebar.
|
A
new 1.4 m – 1.6 m wide concrete platform was formed with a 20 – 30 cm
thickness and supported by temporary formwork scaffolding.
By
the completion of the project, Röhsler & Co expect to have cleared more
than 2,500 m2 without any damage to the rebar or adjacent concrete.
Crossing
over the Prager Strasse interchange presented several problems for the
contractor, not least the height of tramlines below the bridge.
According
to Project Manager, Herr B L Ludwig, “Working with a maximum heading of just
15 cm – almost nothing – was a particular concern.”
He
continued, “We could not close the road or halt the trams.”
A
special steel gantry designed by Röhsler & Co in collaboration with Dywidag,
solved the problem protecting the passing traffic and pedestrians, and enclosing
the Aqua Cutter robot.
Röhsler
maintained a working section of 12 m/day determined by the repeated
repositioning of the rail-mounted covered steel gantry over the edge of the
highway, with live traffic including cars, trams and pedestrians below.
Impact
barriers
The
new improved steel impact barrier meets with the latest EU regulations and an
outer steel and fibreglass infill canopy provides an aesthetic finish and noise
damping.
The
HVD-6000 robot from Swedish specialist manufacturer Aquajet Systems AB was
coupled to a 800 hp Woma pump
supplying water at a pressure with 1200 bar and a flow rate of 200 litres/min.
Röhsler
Austrian
hydrodemolition contractor is no stranger to Aquajet, with more than 10 years
experience with the Swedish company’s Aqua Cutter systems.
Currently,
in addition to the HVD-6000 the company also has an HVD-6000 TC and an older HV-550.
According
to Ing. Rainer Röhsler, all three are in constant use throughout the
hydrodemolition season - determined by the end of frosts - throughout Europe as
well as in special jobs in the middle east.
|
