Page 314 - Bridge and Highway Structure Rehabilitation and Repair

CHAPTER 7 BRIDGE WIDENING AND DECK REPLACEMENT STRATEGY 289

Table 7.3 Useful service life for highway structures
Rehabilitation/ Useful Service Life*
No. Location of Member Protective Measures (Years) Remarks
1A Existing culverts Repairs and/or rehabilitation 25 Can be extended to
50 years with maintenance

1B Culverts with extension Rehabilitation 75 Can be extended to
100 years with maintenance

1C New culvert Replacement 100 Can be extended to
9 100 years with maintenance
2A Existing framed Repairs and/or rehabilitation 50 Maintenance required
sign structures
2B New framed Replacement 75 Maintenance required
sign structures
3A Existing cantilever Repairs and/or rehabilitation 25 Fatigue prone—
sign structures Maintenance required
3B New cantilever Replacement 50 Fatigue prone—
sign structures Maintenance required
4A Ground-mounted Replacement 50 Maintenance required
sound barriers

4B Structure-mounted Replacement 75 Maintenance required
sound barriers

* Varies from project to project and depending on ADT and no extreme conditions of earthquake or fl ood.

• It may be necessary to take disruption of traffic and user costs into account on replace-
ment projects since there would be a change that would impact the traveling public on a
permanent basis.

• Detouring traffic in highly urbanized areas may not be feasible from a capacity point of
view.
2. REP/REH percentage is between 120 and 150 percent.
In this range, rehabilitation or replacement may be the preliminary choice. Other factors
must be examined to establish the appropriate type of work.
3. REP/REH percentage 9 150 percent.
The preliminary choice in this case is rehabilitation. Other factors, such as bridge type, must
be examined to ensure compatibility with rehabilitation.

7.3.7 Cost-Benefi t Analysis
Due to the huge investment involved, reconstruction and maintenance of bridges need to be
considered as running and operating a modern industry. Planning and utilization of funds are
sensitive but important issues. If repairs are not made in time, progressive retrofi t or rehabilita-
tion costs will be incurred. Providing repair costs by a highway agency is mandatory, however,
investing in a new bridge or highway is optional.