On a Slide-In Bridge Construction (SIBC) project, a new bridge is built on temporary supports, usually parallel to an existing bridge. During construction, traffic continues uninterrupted on the existing bridge. When construction is completed, the road is closed temporarily. The existing structure is demolished or removed. The new bridge is positioned ("slid") in place, tied into the approaches, and paved, generally within 72 hours. Variations on this approach include sliding an existing bridge to a location parallel to the original alignment where it can be used as a temporary detour bridge while the new structure is constructed on the original alignment, or using this method to widen an existing bridge.
SIBC offers several advantages:
- All the benefits of other ABC technologies
- Less traffic disruption
- Greater safety for motorists and construction workers (due primarily to shortened work-zone durations)
- Greater quality and constructability
- Reduced environmental impacts from vehicle and construction equipment emissions
SIBC can address concerns that may have limited the expanded use of ABC:
- Slide-in Bridge Construction competes with conventional construction on a first-cost basis.
- Using SIBC, a contractor can build the structure using conventional equipment and still minimize traffic impacts and accrue other benefits.
- SIBC can eliminate construction joints associated with phased construction, leading to a more durable deck.
- SIBC does not require specialized equipment. This increases competition by increasing the pool of contractors with the capability to perform the work.
- SIBC may be suitable in locations where site constraints limit the use of other ABC methods. For example, nationally 94% of structurally deficient bridges cross a feature that is not a roadway; 89% are over a waterway, 3% cross a rail road, and the rest cross some combination of features that include a waterway or railway [2012 NBI data]. SIBC methods can often be deployed to rapidly replace structures crossing non-navigable bodies of water or railroads.
Slide-in Bridge Construction addresses many concerns of stakeholders that have been reluctant to deploy ABC. Greater use of SIBC is giving agencies experience with ABC and showing that ABC projects generate high marks for customer satisfaction. Slide-in bridge construction can serve as a stepping stone to broader use of all ABC methods.