Page 46 - Bridge and Highway Structure Rehabilitation and Repair

CHAPTER 1 OVERVIEW OF BRIDGE ENGINEERING 21

highway code is implemented. The changes can be either less or more based on experience,
judgment, and special conditions present in that state. For projects funded by federal pro-

grams, AASHTO specifications must be followed. The highway agency can approve design
modifications when planning a new bridge based on prevailing clearances of bridges located

on that highway.

1.6.4 Physical Parameters for Reconstruction
Figure 1.10 shows that in addition to material, span length, geometry, and vertical under

clearance, average daily traffic (ADT) volume will have an influence on selecting the type of

bridge for reconstruction.
1.7 A STRATEGIC PLAN TOWARD REPAIR AND REHABILITATION
1.7.1 Adequate Funding Availability
Adding new highways and structures requires considerable funding, both for short-term
construction and for long-term maintenance. Unfortunately, it is difficult to guarantee availability

of sufficient maintenance funds, say 20 years after construction. As more bridges are added to

the current pool, the greater the increase in future maintenance costs.
Highway agencies need to ration their funding between new bridge construction and main-
taining existing ones, with the latter taking priority. One way to control costs is to improvise,
and another is to reduce maintenance costs per bridge with help from modern engineering and
technical know-how. Typical funding sources are addressed in Chapter 2.

1.7.2 Normal Maintenance Procedures
In the U.S., bridge inspectors and structural engineers are responsible for performing inspec-
tions and preparing reports for rehabilitation (see heading number 1.2.4). The following steps
are followed:
1. An inspection report is prepared describing the condition of the bridge, its past history,

diagnosis of defects, methods of repair or retrofit, and cost estimates.

2. Structural inventory sheets and field data are obtained from two yearly inspections by in-
spection teams using the PONTIS system. Remote sensors are also used.

Figure 1.10 Physical parameters to be considered in reconstruction.