Page 309 - Bridge and Highway Structure Rehabilitation and Repair

284 SECTION 2 STRENGTHENING AND REPAIR WORK

pour is to accommodate the differences in deflection that can occur between the new and
the old decks during construction.

7.2 SUPERSTRUCTURE WIDENING
7.2.1 General Guidelines for Design

Widening may require near-term repairs to the existing deck and girders. The objectives are
to restore serviceability and the original functionality following distress from severe localized
deterioration or from vehicle impact damage.
Consider the following physical parameters:
1. Bridge location, pier location, skew angle, and stationing are to be verified in fi eld.

2. Span lengths will be maintained.
3. The number of beams will increase. The type of new beams will be shallower to maintain
minimum vertical underclearance.
4. Similar types of parapets will be built for historic reasons.
5. The pier and abutment will be widened to accommodate the new widths of decks.
6. Utilities supported on the bridge may need to be relocated during construction.

7. New finished grade elevations will match existing elevations.
8. A design exception may be required in some cases if minimum vertical clearances cannot
be maintained.
9. Drainage scuppers will be relocated and redesigned.
10. Closure deck pour between old and new concrete shall be as per technical specifi cations.
11. Existing wing walls need to be demolished, and new walls on new locations are required.
7.2.2 Additional Widening Requirements

Many of the following requirements may be applicable:
1. To ensure the safety of the bridge through increase of redundancy.
2. To keep traffic detour to a minimum. Repairs also require minimal impact to traffi c.

3. To respond to public needs through outreach regarding bridge closure and the construction
schedule. Coordinate with the local communities and adjacent roadway agencies to identify
acceptable reconstruction solutions.
4. To minimize any environmental impact and prevent any river pollution during construc-
tion.
5. To maintain the historic appearance and shape of members.
6. To introduce speed restriction to minimize live load impact.
7. To post the bridge for a lower live load.

7.2.3 Typical Activities

On a bridge widening project, some of the typical activities will include:

1. A field inspection will be made to determine the condition of existing defi ciencies.

2. For work on floor beams and on main trusses, the bridge will be closed for restricted dura-
tion after public outreach is favorable.
3. Some floor beams supporting the deck may have tilted. A minor twist (buckling) to their

web mainly at supports will require web stiffening by bolting web plates. Bolts to stringer
connections will be added. Damaged rivets and bolts will be replaced.

4. Repairing portions of the floor system and the sidewalk damaged by impact from fl ood: All
damaged steel members will be repaired and painted.