BRIDGE REPAIR/REHABILITATION FEASIBILITY STUDY

Visual Impacts: Replacement of the existing lifting beam using a slightly longer and larger beam
section would not likely introduce a visual impact.
4.3.3 Diaphragms/Cross Frames:
NBIS Condition Rating: 6 (Satisfactory)
Condition Description: The midspan timber blocking (diaphragms) between the stringers have
worked loose and rotated in several locations throughout the bridge. Much of the preservatives
have leeched from the surfaces of the timber blocking, thus increasing the risk of surface decay.
However, as the timber wearing surface and structural deck generally minimizes the amount of
moisture to the timber blocking needed to support fungal decay, the risk is currently low.
Repair Scope: In-place preservative treatment of the timber blocking is not recommended for
the same reasons it is not recommended for the timber stringers. As such, the timber blocking
should be replaced similar to that recommended for the timber stringers (see 4.3.1 above).
Rehabilitation Scope: As it may be necessary to modify the stringer spacing in conjunction with
new crash tested timber railing, it may also be necessary to replace some or all of the timber
blocking (diaphragms) to accommodate these modifications and to install additional diaphragms
at the location of the traffic railing posts.
Functionality and Safety: The timber blocking has no significant impact on functionality and
safety.
Load Capacity: The timber blocking does not contribute directly to the load carrying capacity of
the bridge, but is required to brace the timber stringers and thus are considered in the rating of
the stringers. The condition of the timber blocking does not significantly reduce the load
capacity of the stringers.
Maintenance: See 4.3.1 for similar comments regarding maintenance.
Visual Impacts: See 4.3.1 for similar comments regarding visual impacts.
4.3.4 King Posts (Timber Sheave Pole)
NBIS Condition Rating: 6 (Satisfactory)
Condition Description: The timber masts supporting the deflector sheave for the operating
equipment are generally sound, but typically contain significant checks up to 1/4” in width and 4
feet long. The large splits and checks are of a depth that permits fungal spores to access the
center of the member where there are no preservatives, which increases the risk for decay. Much
of the preservatives have leeched from the surfaces of the masts increasing the risk of surface
decay as well. As the masts are vertical members, the exterior surfaces generally do not readily
retain moisture.
Repair/Rehab. Feasibility Study March 10, 2011
Bridge No. C-07-001 (437) 27 Final Report