Max head room: demolition of the Nooderlaan bridge in Antwerp

The Albert canal in Antwerp is being upgraded to allow for improved traffic flow, requiring the raising of the bridges that span the waterway. D&Ri reports

In these ‘green' days, there is a constant requirement to minimise the impact of man's activities on the environment. In Belgium, the waterways system is a major transportation network, but the existing canal and lock network, much of which was built in the early 1900s, is beginning to show its age.

In addition, the nature of the original infrastructure is limiting the capacity of traffic on the network.

Using a 4,500 tonne inland vessel to transport goods replaces 450 lorries on the road and this is the maximum size of vessel that could be accommodated by the Albert canal, which runs from the port of Antwerp to Maastricht and on to Liege.

However, widening the canal and raising the bridges that span it would allow vessels weighing 9,000 tonnes to be used to transport good - one such vessel uses less energy than two 4,500 ships and can carry the equivalent of 900 lorries on the road

In December 2000, the Flemish Government developed the Masterplan Mobility Antwerp, which was approved on 15 December 2000 and was intended to improve mobility, traffic safety and the quality of life in and around the city of Antwerp.

To complete this Masterplan and coordinate the various projects involved in the masterplan, the Flemish Government set up the public limited company Beheersmaatschappij Antwerpen Mobiel (BAM), which began operations in 2003.

The work is being carried out in two phases, with five bridges (including the Nooderlaan) north of the Straatsburg dock being replaced by new higher bridges, and the canal under these bridges being widened over the period 2008-2014, while in the second phase two bridges further north will be raised and a new cycle bridge will be built from 2014 to 2016.

In addition, two locks on the canal will also be renovated over the period, with all works estimated to cost E308 million (US$450 million).

Noorderlaan bridge

BAM contracted Belgian contractor Aertssen to carry out the work on the Noorderlaan road bridge

This bridge over the Albert canal was of steel and concrete construction, with five steel I beams supporting a concrete road deck.

Aertssen first constructed the new higher bridge alongside the existing structure, along with all approach works before tackling the removal, which had to be carried out over two weekends because of vessel traffic issues on the canal - the Albert canal is a busy waterway and could only be closed to traffic at this time.

On the first weekend, he concrete road surface was removed. The roadway was cut lengthwise over the steel support beams, and also cut laterally using a concrete saw. The resulting slabs of concrete of concrete were then lifted and removed by one of the company's fleet of excavators, in this case a Caterpillar 325D with a bucket. It was then removed from site for recycling.

The following weekend was reserved for the removal of the five 30 m (99 ft) steel beams that supported the road deck. The lift was planned in two phases, with the first being the heavier of the two at 260 tonnes - this consisted of three of the steel beams. Both lifts were simple in concept.

Once the beams were freed from the bridge supports on both banks, which was carried out on the Saturday, the sections were lifted by two of Aertssen's mobile cranes, one on each bank, with the crane on the south bank acting as a pivot point, supporting the load of the beams during the other phases of the lift.

The crane on the north bank of the canal lowered its en end of each bridge section was lowered onto two SPTM modules mounted on a barge moored to the bank.

Once this had been done, the barge cast off and manoeuvred across the canal to a point on the south bank were a third crane then lifted the end of the section from the barge and lowered it to the bank, where the steel structure was cut up into more manageable sized sections for disposal and recycling.

Aertssen used a brand new Demag CC 2800-1 crawler crane as the ‘pivot' machine on the job - this was in fact the very first lift the crane had carried out for the company following its delivery from the factory. Two Demag all-terrain cranes provided the other lift capability.

The second lift was complicated by the fact that the outer beam of the two beam section actually lay underneath the new bridge structure, so the section had to be lifted clear of the supporting structure, swung clear of the new bridge, at which point the full lift could take place.