Page 59 - Bridge and Highway Structure Rehabilitation and Repair

34 SECTION 1 ADMINISTRATIVE ISSUES

Chapter 3 addresses the issues contributing to the failure of bridges, in particular those
which were least maintained or neglected, and the impact failures have on the future approach
to maintenance of existing structures.

1.12 PRESERVING AESTHETICS
1.12.1 Planning to Ensure Safety and Operation

1. One of the most significant design factors contributing to the aesthetic quality of the structure
is unity, consistency, or continuity. These qualities will give the structure an appearance of
a design process that was carefully thought out. Sound planning also leads to safety and
effective operation at intersections.
2. Aesthetics is required for rehabilitation: A bridge should have a pleasant appearance. As the
old saying goes, “A thing of beauty is a joy forever.” It should have a visual relationship with
the surrounding area and also have visual impact. The famous structural engineer Hardy
Cross laid down the criteria of a beautiful bridge: “The first requirement of a beautiful bridge

is that it must stand up long enough for us to look at it.”
New bridge facades should preferably blend with the appearance of existing bridges in the
vicinity.
3. Bridges should have an open appearance and avoid abrupt changes in elevation or curvature.
Abrupt changes in beam depth should be avoided when possible. Whenever sudden changes
in the depth of the beams in adjacent spans are required, care should be taken in the develop-
ment of details at the pier.
• Avoid mixing structural elements, for example, concrete slab and steel beam superstruc-
tures or cap and column piers with wall type piers.
• In general, continuous superstructures shall be provided for multiple span bridges. Where
construction joints cannot be avoided, the depth of spans adjacent to the joints preferably
should be the same. The use of very slender superstructures over massive piers needs to
be avoided.
• Lighting can make a big difference in the aesthetics of a bridge (Figure 1.13).
• Use of precast mechanically stabilized earthwork (MSE) walls.
For abutment, wing wall, and retaining walls, MSE walls are gaining popularity due to their
elegant styles, low cost, and quick construction.
4. Normally it is not practical to provide cost premium aesthetic treatments without a specifi c
demand; however, careful attention to the details of structure lines and forms will generally
result in a pleasing structure appearance.

Figure 1.13 Lighting and its refl ection in the water is important to the aesthetics of a bridge.