The deck erection gantries for the 1490m span Runyang suspension bridge were designed and supplied by DLT Engineering to RBG. 2nd Highway Engineering Bureau, the main contractor for the project. The main span of the steel bridge deck was been split unto 47 deck units, each weighing up to 470 metric tonnes. These were fabricated offsite and transported by barge into position under the main cables where they were erected using the deck erection gantries.

 

 

 

 

 

 

The gantries were designed in the UK to British standards. All mechanical components and the control system were manufactured in Europe and shipped to site. The steel structure of the gantries was fabricated in China. Once all components were on site the gantries were assembled, tested and erected within a period of 3 months. The fully assembled gantries, including deck lifting beams, were load tested to 125% of safe working load and function tested on a specially design test frame.

The gantries are a new design, with many new features incorporated including:

• Designed for re-use on future bridges with varying cable centres and cable diameters.
• Self erection and dismantling from the main cables at any point along the bridge. The gantries can also be erected and dismantled adjacent to the bridge pylons using tower cranes.
• Modular, lightweight construction for economic transport between sites. Fully operation, each gantry weighed a total of only 130 tonnes including deck lifting beams.
• All systems fully computer controlled for ease of use and for synchronisation of strand jacks during deck lifting and gantry erection/dismantling.
• Fine adjustment of bridge deck level to within +/- 0.5mm.
• Able to walk over cable bands of up to 1.9m long and 0.3m rise above the cable.
• Able to incline the lifting strands through an angle of up to 15 degrees to the vertical to allow deck units to lifted away from final plan position and swung across into final position.
• All components weatherproof to IP65 and able to operate in temperatures down to minus10 deg. C.

Each pair of gantries is capable of erecting deck units at a rate of one per day, but in practice the deck erection programme was dictated by the delivery schedule of the deck units. The gantries were operated by local labour under the supervision of Dorman Long. Erection of all 47 deck units took 12 ½ weeks, the last closure unit being erected on 17th April 2004.

Gantry self erection sequence: