Even the Eiffel Tower is dwarfed by a pair of new suspension towers near Shanghai. The 346.5 m-high structures are the tallest of their kind in the world: their sole purpose is to carry power lines over the Yangtze Kiang River. Access for service and maintenance posed unique challenges and the solution has been to install a specially-adapted ALIMAK SE 400 FC industrial lift in each tower.
This saves crews from having to climb structures which are taller than all but a dozen or so of the world’s highest buildings. The Alimak lifts carry maintenance staff 330 m up to the highest access levels of the towers at a steady speed of 0.8 m/sec so the journey takes just seven minutes. The only other way up involves climbing a dizzying spiral staircase which turns around the lift’s core structure.
The towers stand 2.3 km apart, each occupying a base footprint with a side of 68 m. They have cross arms 72 m wide, carrying the high-voltage power lines across the river. It is a major shipping route and the height of the towers was dictated by the need to provide adequate clearance under the power lines.
Despite the huge size of the towers, the space available for the lifts was very limited and it has required considerable ingenuity to adapted existing models in the ALIMAK SE range.
The combination of limited space and enormous height made the installation unique and considerably more difficult than the container cranes, cement industrial plants, marine facilities and steel mills where the SE series is more commonly used.
There have been thousands of installations of Alimak’s versatile SE system around the world. Most applications can be catered for using the standard range, which has capacities from 300 kg to 2,400 kg, a choice of 30 car sizes and wide options covering factors such as the degree of automation, extras and the materials used.
Alimak had to ensure that the complete lift structure would fit into an area just 1.5 m in diameter. The available space was less than the smallest existing car produced. This resulted in customised lifts based on the ALIMAK SE 400 FC but manufactured with rounded fronts and doors to save valuable millimetres. The ride to the top is not for the claustrophobic as the overall car dimension is just 715 mm by 910 mm.
These space restrictions meant that the whole stainless steel electrical cabinet had to be placed on the car roof, rather than being integrated into the wall as would normally be the case.
Customisation of the ancillary equipment was also needed as the lift height was more than 30% greater that the standard Alimak range.
The lift shaft structures were assembled on site from 12 m-high prefabricated durable hot-dip galvanised steel sections and installed on completion of the main steel structure.
Each lift has five separate landings. These continue with the rounded shapes corresponding to the lift profile.
The towers were built by a joint venture of Cleveland Bridge and Balfour Beatty Power Networks. They are part of the East China (Jiangsu) Power Transmission Project and are needed to distribute of 500 kV electricity from YanCheng Power Station in Shanxi Provence in the north of China to Dou Shan Substation in Jiangsu Province in the south of China. Each of the massive structures contains 4300 t of steel, held together by more than 200 t of bolts and they have been designed with a maximum sway of up to 2 m at the top point.