Disadvantages of cantilever bridge construction include special gantries needed to support the weight of the bridge, complicated bridge maintenance over many years and that the geometry of the bridge's design depends on stage construction and timeframes of building the structure. Construction requires massive, heavy forms, which increases costs over the entirety of the project.
Cantilever bridges are built in regular stages, so construction times and crews have normal, steady work. However, special equipment is needed to haul heavy loads. Massive gantries and huge cranes place parts of cantilever bridges over the whole span of the bridge. Once equipment is in place, the work proceeds smoothly.
For longer spans and larger bridges, heavy trusses must be placed to ensure that roadways are supported properly. Tensile forces push and pull the bridge, so cantilever designs must be heavier to displace the forces that act on the spans between supports.
Cantilever bridges are marked by supports on one end, and roads that project toward the middle. Cantilevers that meet in the middle are similar to two springboards that reach out to a midpoint. These spans reach up to 200 feet across. Steel-reinforced concrete forms that make up cantilever bridges are pre-cast and then put in place onsite with no need to pour concrete at the construction zone.