The most prevalent and cost-effective technique for bridge girder erection involves the use of cranes. This method, however, requires clear ground-level access along the span. It also needs enough operational space to accommodate the crawlers or outriggers, the counterweight assembly, the driver's cab, and the overhead projection of the boom and rigging. A variety of cranes, each tailored to the unique project requirements, are used for bridge girder erection. The following are the types of cranes frequently used in this process.
Mobile Cranes: These are standard, versatile cranes that are extensively used in bridge construction projects today. They commonly have a lift capacity range up to about 300 to 400 tons and feature an adjustable boom or arm that can be modified to cater to the unique requirements of a project. While they provide an excellent balance of mobility, reach and lift capacity, they may not be the top performers in any single area. Some popular examples include the Liebherr LTM 1300-6.2 with a lift capacity up to 300 tons, the Grove GMK5250L with a lift capacity of 300 tons and known for its maneuverability, and the Tadano ATF 400G-6 which offers a high lift capacity of up to 400 tons. The LTM1400, a 500 ton mobile crane was used in the Metrolinx Bloor Street West Rail Bridge Project to relocate a steel bridge span.
Crawler Cranes: These cranes are famous for their excellent stability and are ideal for lifting heavy weights, with capacities ranging from 300 to 3000 tons. They operate efficiently on varied terrains but have limited speed. They are best suited for long-term projects where heavy lift capacity is a primary requirement. Kobelco CKE2500-2, for example, is a versatile crawler crane with a lift capacity of around 250 tons. Liebherr series LR1300 to LR13000 are suitable for heavy lifting ranging from 300 tons to 3000 tons. In the New Pattullo Bridge project, an LR1300 crawler located on the Surrey shore is used to assist in the erection of the pier table segments and the structural steel for the end span of cable-stayed portion of the project. On the MLX MacKay River Bridge project in Alberta, an 825-ton Manitowoc M18000 with a 21000 MAXER was used to lift the north girder segments at a 250' radius.
All-Terrain Cranes are highly versatile, designed to navigate both on-road and off-road sites. They have a lift capacity ranging from approximately 400 to 1200 tons. Their high-speed capabilities make them ideal for projects that require frequent movement between sites. However, they might face challenges on extremely rough terrains. Notable examples include the Grove GMK6400 (lift capacity around 400 tons), the Liebherr LTM 11200-9.1 (lift capacity approximately 1200 tons), and the Demag AC 500-2 (lift capacity up to 500 tons). Each of these examples showcases a unique combination of significant lifting capacity and flexibility. A 300T GROVE GMK6300 L-1 crane was used to lift the box girder segments for the Hwy17 Calabogie Road Bridge in Ontario.
Rough Terrain Cranes: As the name suggests, these cranes are designed specifically for rough terrains. They come equipped with large rubber tires and compact frames and offer lift capacities up to 120 tons. They excel in off-road projects but may lack the speed for transportation between different sites. Some examples include Terex RT 90, Link-Belt RTC-8090, and Grove RT765E-2, all known for their durability and versatility in rough terrains. A 75-ton Link-Belt HTC 8675 was used to assemble the truss spans and for erecting the deck panels for the Queensview Pedestrian Bridge in Ontario. The lifting of the assembled truss spans was performed by an LTM1400, a 500 ton mobile crane. See video below on the erect process.
Telescopic Cranes: These cranes offer both height and versatility with lift capacities of around 220 tons. Their unique hydraulic mechanism allows for adjusting the boom length. They're well-suited for projects requiring both reach and mobility but may struggle with very heavy loads. Some examples are Tadano ATF 220G-5, Grove TMS9000-2, and Liebherr LTM 1130-5.1, all known for their flexibility, high capacity, and strong lifting performance.
Tower Cranes: These cranes are used when height is a major factor, offering lift capacities around 25 tons. They can reach higher than any other cranes, making them perfect for constructing tall bridges. However, they are stationary and require significant setup time. The Potain MDT 809, Liebherr 280 EC-H, and Terex CTT 561-20 are some examples, known for their high lift capacities, reach, and efficiency in tight spaces.