what are the benefites of using of precast bridges over cast in-situ bridges?
There are different types of precast bridges. prestressed girders bridge is very common. method of constructing foundation and piers are similar to cast in-sit bridges but there is a major difference in constructing the superstructure. in precast bridges girders are placed above piers then top slab is casted or installed in the event of using precast concrete for top slab. for cast in-situ bridge, falsework are required. falsework is a temporary structure used to support the superstructure of the bridge until it becomes self-supporting. Then formwork for superstructure will be erected and finally, concrete will be casted after completion of reinforcement works. this a quick summary about precast and cast in-situ bridges. precast bridges benefits can be summaries as follow:
- The production of bridge girder will be done at the plant in bulk numbers. so it can be produced once the project begins. Once the substructure is ready it will be erected immediately and simultaneously. on the other hand, the process for cast in-situ will take a long time because all casting will be done at the site. so it is step by step and time-consuming construction.
- in precast bridges, there is no need for supporting girders because it has been casted before and given enough time to cure and attain the desired strength. for cast, in-situ bridges falsework are required to support bridge superstructure until it reaches the desired strength. the using falsework may require partial or full closure of roads. this will result in a traffic jam and inconvenience for commuters.
- Precast bridges required lesser time. in addition to the reduction on construction time, falsework and formwork for superstructure are eliminated. so there is a potential saving in precast bridges overcast in-situ bridges