Page 27 - Bridge and Highway Structure Rehabilitation and Repair

2 SECTION 1 ADMINISTRATIVE ISSUES

1.1.2 Benefits of Rehabilitation
1. Improved structural performance based on:
• Redundancy—Examples are the use of continuous spans, provision of alternate load paths,
and reduction of fatigue in fracture critical members.
• Fatigue performance—Examples are the use of HPS with increased ductility and energy
absorption, use of prestressing to reduce tension stress range, and elimination of details
more critical than AISC category C.
• Resistant design against extreme events—such as for earthquakes and foundation scour.
2. Serviceability: Examples are provisions for deck replacement and widening, durability,
maintainability, and inspectability.
3. Economy: Examples are the reduction of life cycle costs, and use of efficient design and

construction methods, structural details, HPC, prestressed or steel grid decks, weathering
steel, and HPS.
4. Constructability: Examples are ease of fabrication, weldability, transportation lengths to

eliminate field splices, and ease of erection with minimum disruption to traffi c.

5. Diagnostic design: It is project specific and site specific. It differs from new bridge design

in a number of ways by requiring:
• Structure condition evaluation and load rating
• Alternative analysis and computer applications
• Use of new repair materials and state of the art rehabilitation techniques
• Staged construction
• Modern construction techniques
• Decision making models such as decision matrix, life cycle costs, and risk analysis.

Table 1.1 shows a list of topics for bridge and highway rehabilitation and related issues cov-
ered in this book. In this chapter, an overview of the factors leading to successful maintenance
is presented, and a brief history of some of the old and best-kept bridges is provided.

1.1.3 Rehabilitation Is a Means to an End and Not an End in Itself
The bridge is only a small part of the highway. Rehabilitation activities comprise many as-
sociated civil engineering disciplines and tasks depending upon the complexity of the project,
namely:
• Constraint management including scope, schedule, and budget
• Community outreach and public involvement
• Acquiring the right of way
• Surveying
• Utilities relocation
• Maintenance and protection of traffic or stream fl ow

• Temporary signals, signing and striping
• Drainage
• Approaches and sidewalks
• Geotechnical engineering
• Inspections and monitoring
• Environmental concerns and acquiring permits.
Hence bridge engineer needs to work as part of a team and not independently.