Over two years at Wood Research and Development, I produced restoration drawing packages for twelve timber bridges across New Brunswick and Nova Scotia. Each bridge presented a unique combination of structural condition, site constraints, and owner requirements. Here is what the restoration process looks like from the drafting side.
From inspection to design
Every restoration starts with a Level II inspection report. The condition ratings and damage sketches from the field directly inform the scope of restoration. A bridge with localized pile decay needs a different approach than one with widespread superstructure deterioration. We prioritize based on safety risk, remaining service life, and owner budget.
Structural analysis phase
Before any drawing is produced, we run structural analysis in LUSAS to validate the restoration concept. Key checks include:
- Member capacity verification per the Wood Design Manual (CSA O86)
- Live load distribution for the restored section
- Connection capacity at retrofit locations
- Deflection serviceability under design loading
The analysis often reveals that the restoration strategy needs adjustment — a splice detail might need to be moved to a lower-stress zone, or additional fasteners might be required at a connection.
Drawing production
The drawing package typically includes:
- A general arrangement plan showing the bridge in plan and elevation
- Pile layout and replacement details
- Component-specific restoration sheets (stringer repairs, deck replacements, bearing upgrades)
- Connection details at every retrofit location
- Quantity and material schedules
Lessons learned
After twelve bridges, a few patterns stand out:
- Field conditions always differ from the original drawings — expect surprises and build review cycles into the schedule.
- Contractor feedback during drafting improves constructability significantly. A detail that works in CAD might be impossible to execute with a timber crew working from a boat.
- The bridges that perform best after restoration are the ones where the drawing set included clear phasing and staging plans for the contractor.
The most satisfying part is seeing a bridge that was load-restricted before restoration return to full service after the work is complete. That is what makes structural drafting in this field rewarding.