BRIDGE REPAIR/REHABILITATION FEASIBILITY STUDY

navigation opening before they will grant a permit, which can lead to delays in the project.
There are numerous examples of this that can be found throughout the United States (e.g. 1993-
1994, Blackburn Point Swing Bridge Rehabilitation, Nokomis, Florida, a swing bridge listed on
the National Register of Historic Places.)
Although it is always possible to identify a different scope of work that minimizes the number of
components to be replaced, this potentially reintroduces the numerous other significant concerns
such as significantly increased construction cost, increased required maintenance, increased
deterioration that can eventually result in load restrictions and/or reduced service life, potential
for environmental contamination or human health risks, and reductions in safety.
5.2 Maintenance and Service Life
The current condition of the timber varies throughout the bridge from “satisfactory” to “poor”
depending on the element (see Section 4 above.) In addition, the condition of the timber
throughout the bridge is of a condition that is conducive to continuing deterioration, and thus it is
anticipated that the timber will continue to deteriorate unless corrective action is taken.
Continued deterioration will result in loss of section and corresponding loss in load carrying
capacity. Although the current deterioration has not reduced the load carrying capacity to a level
that requires load restrictions, it is anticipated that the deterioration will eventually reach a level
where load restrictions may be necessary. Without corrective action, the deterioration would
ultimately expect to reach a level where the bridge would be unsafe to carry traffic.
In consideration of the current conditions, a “do nothing” approach including normal
maintenance will not correct the conditions that cause the bridge to deteriorate and make it
“Structurally Deficient”. Furthermore, currently available maintenance and repair techniques
will not extend the service life of the timber elements of the bridge a reasonable duration in this
environment.
As different timber elements of the bridge are in different condition, the service life and
maintenance requirements are also different for each element. Due to the wide variety of factors
that contribute to deterioration, it is difficult to estimate with accuracy the remaining service life
of timber members. However, experience with similar bridges in similar environments in
Massachusetts provides some guidance in this area. An estimate of the remaining service life for
each of the existing members and an estimate of the overall service life for replacement members
is as follows:
Repair/Rehab. Feasibility Study March 10, 2011
Bridge No. C-07-001 (437) 49 Final Report