Streatham Station bridge was originally constructed in 1850 with cast iron beams and brick jack arches spanning between them. The central section was strengthened in the early 20th century by the replacement of the cast iron beams and brick arches with concrete encased steel beams.

Scope of Works:

• Provide temporary access during rail occupation periods
• Vacuum blast the cast iron beams and apply primer
• Supply & install ultra high modulus carbon fibre plates
• Supply & install a bracketing system

Recently Transport for London (TFL) wanted to introduce a bus lane over the bridge and the remaining original cast iron beams on the east side were deemed structurally inadequate for the new loading.

CRL were contracted by TFL to supply and install ultra high modulus carbon fibre reinforced polymer (CFRP) laminate reinforcement glued to the cast iron beams to enhance the load capacity plates on the ten full span cast iron beams during a series of rail occupation periods.

The beams were vacuum grit blasted to recover all lead contaminated paint and the prepared surfaces primed. The CFRP plates were a maximum of 50mm thick in the middle tapering towards the ends. The plates were specifically manufactured. The work was carried out during two consecutive summers to ensure suitable ambient temperatures for the adhesives. The majority of the plates were installed during a 28 hour weekend possession. After installation the plates were held in position using temporary brackets while the adhesive cured and these were removed a week later.

The work was completed on time for TFL to implement the addition of the new bus lane and the reduction in headroom over the rail lines was only 15mm on completion.

Client: London Underground Ltd

Value: £1.6 Million