The 1915 Çanakkale Bridge spans the Dardanelles at the western end of the Sea of Marmara. Part of the Kınalı-Balıkesir Motorway in the northwest of Turkey, it is the longest suspension bridge in the world. The 2023 m long main span leaves a 1600 m x 70 m navigation channel. Two 318 m steel towers support the main suspension cables at 38 m separation. The deck comprises a pair of 14.5 m wide, 3.5 m deep aerofoil steel box girders connected at intervals by transverse box girders. Eight 450 t capacity lifting gantries were required for deck erection, two for each side span and four for the main span. There were 153 deck segments to be erected, of which 143 were erected with the gantries. The gantries were self-erected onto the main cables. Environmental conditions and maritime traffic in the strait were key factors in the development and choice of construction methods for the bridge. This paper describes deck erection with the lifting gantries and focuses on the development, design, testing and operation of the self-erection system; an innovative solution which maximises pre-assembly off the critical path, minimises disruption to shipping and allows installation of the gantries without floating cranes.

The Nizhou waterway bridge, part of the Second Humen Bridge over the Pearl River in China's Guangdong province, is the second longest suspension bridge in the world (1688 m main span). The reinforced concrete towers are 260 m tall and the main cable spacing is 42·1 m. The deck is an aerofoil-shaped orthotropic steel box 49·7 m wide and 4 m deep. Deck erection took place during the spring of 2018. Three 500 t safe working load deck erection gantries, supported on the main cables, lifted 175 deck segments into position in 10 weeks. Strand jacks were used for deck lifting and gantry relocation. This paper describes the deck erection gantries, from concept development, through detailed design and testing, to operation on site. It focuses on the innovative movement system specifically developed for this project to reduce operating cycle times and overcome the design constraints, particularly the large range of relative positions between the deck erection gantry and the cable bands. Cast nylon wheels and aluminium ramps were designed for the gantry to roll smoothly over cable bands. Insufficient industry guidance on the design of cast nylon wheels and their interaction with the main cables required a multidirectional approach, which involved hand calculations, finite-element analysis and testing.