Civil Engineering Reference
In-Depth Information
L
H
c3
H
2
Base-of-rail
H
4
H
w
Grade,
g
Elevation
L
2
L
1
W
3
Plan
FIGURE 3.11
Basic dimensions of a railway bridge crossing.
persons. However, there are some basic tenets of aesthetic bridge design that appear
to be generic in nature (Leonhardt, 1984; Billington, 1985; Taly, 1998; Bernard-Gely
and Calgaro, 1994).
Harmony is often of primary importance to the public who generally desire bridges
to integrate and be compatible with their environment.
∗
Therefore, the bridge should
be of materials and form suitable to achieve cultural and environmental congruence.
The bridge should also be expressive of function
†
and materials. In this manner
the bridge will be a visual expression of the engineering mechanics and mathemat-
ics involved in achieving safety, efficiency, and economy. However, the economical
proportioning of bridges does not necessarily produce aesthetic structures and other
issues, in addition to harmony and expression of function, also warrant careful
deliberation.
Proportion and scale are important.The dimensional relationships and relative size
of components, elements, and/or parts of steel railway structures may affect public
perception and support for the project. Slenderness, simplicity, and open space
‡
often
contributetowardattainingpublicacceptanceofrailwaystructuresconstructedinboth
urban and rural environments. Ornamentation that conceals function should generally
be avoided.
The arrangement, rhythm, repetition, and order of members and/or parts of the
structure are also essential deliberations of aesthetic bridge design. Light, shade,
color, and surface treatments are further means of aesthetic improvement in structures
within urban or accessible rural environments.
∗
The requirements related to environmental compatibility will vary depending upon whether the bridge
is to be constructed in an urban or rural environment.
†
Sullivan's famous “form follows function” statement on architecture applies well to bridges, which are
often most aesthetically pleasing when designed primarily for economy and strength.
‡
Structures that look enclosed or cluttered are often unacceptable from an aesthetic perspective.
