Page 69 - Bridge and Highway Structure Rehabilitation and Repair

44 SECTION 1 ADMINISTRATIVE ISSUES

• Address environmental concerns
• Increase capacity
• Improve geometry—sight distance
• Correct defi ciencies
• Future widening
• Improve horizontal and vertical under clearances
• Correct joints and bearing problems
• Improve deck and drainage.

2.1.6 Structural Solutions
1. In general, most recurring maintenance problems would require unique structural solutions
for restoration and strengthening. Although rehabilitation is usually associated with older
bridges, it may be required for newer bridges when planning, design, or construction mis-
takes are made. The capacity of existing bridges built for a lighter live load are fully tested
when heavier vehicles are permitted.
Fewer maintenance problems are likely to occur when live loads are small (such as with
pedestrian or cyclist loads) compared to those by repeated heavier trucks or permit loads.
2. Rehabilitation of bridges is a far more diverse and challenging subject than a new design
based merely on code compliance. For maintenance of an existing bridge, there are fewer
alternatives available to the designer than when designing a new bridge.
Some common rehabilitation examples include:
• Replacing a collision damaged fascia girder
• Replacing deck joints and bearings by jacking the superstructure
• Repairing cracks in a deck slab or in an earthquake damaged concrete pier
• Strengthening unknown foundations by underpinning with mini piles to prevent soil
erosion
• Bridge performance can be upgraded by seismic retrofit, scour countermeasures, and by

widening to provide additional lanes, shoulders, or sidewalks.

2.2 THE REHABILITATION PROCESS
2.2.1 Inspection Reports and Planning Issues
Recommendations are provided in inspection and rehabilitation reports for emergency re-
pairs, which should be implemented as soon as possible. Options include the following courses
of action:

1. No reconstruct option is to dismiss the problems for some good reasons. The scope of work,
type of design, construction effort, and cost are evaluated before a decision is made.
2. In extreme cases, the bridge may be shut down indefinitely. A temporary detour is

followed.
3. In other cases, some lanes may be closed to reduce the risk of failure by reducing live loads.
A partial detour in one direction only may be used.
4. The client's emergency repair funds make immediate repairs possible.

2.2.2 Quality Planning
1. Rehabilitation generally involves hundreds of man hours of diagnostic design and several
years of work before the bridge is fully restored. Over the years, an engineering system has
evolved which requires creativity, innovation, ingenuity, constructability, cost effectiveness,