Extraordinary check of the footbridge
With the participation
of Ing. Roman Šafář, Ph.D., a certified bridge engineer and the holder of
authorization to conduct main and special inspections of bridges, a special
inspection of the bridge for pedestrians and cyclists across the Berounka river
in Radotín was carried out on 9 and 12 December.
A planned check of the footbridge
had been carried out half a year earlier to make sure that it could be used
until a new bridge was opened. That should be built in 2018 and until then the
regime for the use of the connection between the two banks will be set so as to
avoid a sudden increase in load on the bridge structure.
Extraordinary check of the footbridge, 21.12.2017
The footbridge, which connects the
Radotín and Zbraslav banks of the Berounka river, is managed by Prague 16 City
District which, after the floods in 2013, commissioned Mr Šafář from ČVUT
(Czech Technical University in Prague) to check its structure and, on the basis
of recommendations resulting from his expert assessment, ordered the footbridge
to be secured with a steel supporting structure. Two solid supporting posts in
the river bed were installed in the summer of 2014 by JHP mosty according to a
project drawn up by Pontex, s.r.o. (the total cost was 2,700,000 CZK).
A specialist check was to have been
carried out in the spring of 2018, but in response to the collapse of the
footbridge in Prague-Troja, the town hall decided to have the bridge checked
now. A visual assessment of the state of the supporting parts of the structure
took place on 9 and 12 December with the use of a boat, a high-lift platform
and climbing equipment.
A support structure has been
designed and built to secure the bridge in the event of a sudden break. It is
not connected directly to the bridge deck so as not to interfere with the
distribution of forces between it and the pylon, but the footbridge could rest
on it if the load-bearing elements were disrupted. However, the footbridge
itself is designed in such a way that, in addition to the tensioning steel
ropes in the main supporting structure, it is also supported by a system of
hinges led through the pylon. Temporary securing with support pillars is just
another safeguard.
Prague 16 Municipal Authority is
taking all these steps to maintain the connection between Radotín and the
opposite Zbraslav bank, while maintaining maximum safety. “We realise that for
some people any closure of the Radotín footbridge would be a serious logistical
problem - it is an important communication link for pedestrians and cyclists because
the nearest other possibility to get from one side of the Berounka river to the
other is in Lahovice or Dolní Černošice,” adds Karel Hanzlík, the mayor of
Radotín. “The construction of the footbridge here is different, in Troja it was
a suspended structure, what’s known as a suspended pre-tensioned belt. Here we
have both internal cables and external hinges - and three years ago, we added
lower locking.”
The conclusions of the special
inspection are short-term and longer-term measures which will make it possible
to maintain limited operation of the footbridge until the new bridge is built -
but until 2020, at the latest.
The short-term measures include the placement of barriers to prevent
motorcycles and cars from going on to the bridge, the placement of a traffic
sign indicating that the footbridge can only be used by individual persons,
banned entry on to the bridge at a wind speed of over 10 m/s, and a warning
sign pointing out the unevenness of the walking area on the bridge. These
measures will be implemented as soon as possible.
Longer-term measures include extending the temporary support of the
footbridge and adjusting the bridge’s hinges according to the project
documentation.