The cable-stayed Meitarim, or Chords, bridge will curve 150m over a busy intersection at the entrance to the city on the Jerusalem-Tel Aviv Road, when finished in 2009. Instead of an arch, the unusual bridge designed by Spanish-born architect Santiago Calatrava is supported in the middle by a single steel girder pylon that soars upward 120m at a 60-degree angle. Calatrava has said that he intended the bridge to suggest a harp, the instrument of King David.
A Liebherr LR?1800 crawler crane is the star of the project to make Calatrava’s vision a reality. The crane is lifting sections of the deck and the pylon. The crane is hired by contractor Koor Projects from owners Israeli Electric Company, who use it for power station assembly. Koor Projects is the project management subsidiary of Vulcan Engineering, manufacturer of the pieces of the pre-cast concrete viaduct.
The 160m bridge currently rests on seven temporary supports about 6m above the road deck. One of the temporary supports sits in the middle of the Shazar Road. Deck sections are 30m (99ft) long, 4m (13ft) wide, and weigh between 130t and 150t each. Three sections side by side make up the 13m (42.6ft) bridge deck. The crane was rigged with 56m (184ft) S-boom and 43m (141ft) backmast, with 340t of counterweight on the superlift attachment, and an additional 168t on the crawler carbody.
The project team moved the crawler crane across the road three times to lift deck sections into place. Despite 500t of counterweight and 100m (328ft) of boom, the crane crawled across the Shazar road, covered with steel sheets, three times without damaging the road. The pylon and pylon foot combined weigh a total of 1,400t. The foot came in two 180t pieces, and the pylon is divided into eight 130t 15m (49ft) long steel box sections that are welded together. To raise these to the necessary height, the crawler was re-rigged in October with a 63m (207ft) luffing jib with 56m (184ft) main boom, for a 120m (394ft) total system length.
The crane will only need to hook the highest piece at a height of about 103m (337ft), because the load’s centre of gravity is beneath that height. By mid-October, the pylon was more than half-erected. The crane lifts individual sections complete with sections of scaffolding. Workers climb up this scaffolding to bolt the section in place on top of the pylon with temporary brackets, and then weld all the way around. The crane hooks two lifting slings on to lugs welded on the steel box sections. Because the pylon rises at an angle, a 10t chain block attached to the pylon pulls a section hanging from the crane into line.
Once the pylon is erected, which Frischmann estimates will be by the end of the year, Koor will return the big crawler, and use winches and aerial work platforms to install the 70 2t cables that will support the bridge. Then, in March, it will take away the temporary supports and let the bridge hang free.
The crawler lifts a section of the steel box section for the arch The crawler lifts a section of the steel box section for the arch A chain sling on the hook block keeps the section at the right angle A chain sling on the hook block keeps the section at the right angle