The brief
The redevelopment needed the old crossing over the beck replaced with a new steel bridge. The engineer's design set three universal beams side by side carrying the deck, with a steel parapet along both edges.
What we did
- Modelled the whole bridge in Tekla Structures and issued general arrangement drawings - a 3D view, a plan and four sections - for approval
- Worked the design team's mark-up into the set: the base plates went from 12 to 15 mm, and one abutment was given slotted holes (22 x 30 mm, running with the span) so the bridge can move with temperature
- Issued a full fabrication package: assembly drawings for the three beams and the two handrail frames, single-part drawings, a part list and NC files for our cutting and drilling
- Fabricated the beams and parapets in our workshop in Ash, Sevenoaks, and arranged hot-dip galvanising with our specialist partner
- Re-planned delivery when the client chose to install the steel with their own site team: the three beams first, then the parapets as soon as they are ready
Details that mattered
- The 100 mm rule. The "100 typ" infill note is the clear gap, not the spacing. That gives 50 mm infill at 150 mm centres, 40 members a side, so no gap lets a 100 mm sphere through
- Thermal movement. Fixing both ends rigidly would lock in stresses as the steel warms and cools. Slotting one end lets it move while still holding it in place
- Galvanising. A bridge over water needs a finish that lasts, so every member is hot-dip galvanised after fabrication
Timeline
- June 2026Quotation from the engineer's design
- 2 July 2026Tekla drawings issued for approval
- 26 August 2026Drawings approved, with a slotted-hole detail added
- 8 September 2026Fabrication package issued
- October 2026Programme changed: beams delivered first, parapets to follow, installed by the client's team