Project Details
Description
The scheme is required to design and replace a subframe to support the walkway currently present within the box girders on the M90 Friarton Bridge, Perth. At present, the walkway is defective and substandard in its supports and handrails. Defects noted during recent inspections include the walkway buckling in the struts which support individual sections and sections of handrail which are loose or have collapsed. The current Glass Reinforced Plastic (GRP) mesh walkway bends under the loading of one person (approx. 75kg) and deflection was observed at 20mm, passing the allowable maximum by 10mm.
Construction activities for the scheme will entail the fixing of a subframe to the existing box girder stiffeners to support the GRP walkways. The subframe will consist of a channel section or ‘I’ beam the full length of a single panel, positioned at each side of the walkway with an attached handrail to provide additional edge protection. All construction activities will be contained within the box girders themselves with materials being moved to-and-from the box girder to staging areas at either end of the structure. The works include:
- Edge protection for fall prevention;
- Sub-frame installation; and
- Handrail installation.
Plant, vehicles and machinery required for the scheme include:
- Mobile-elevating work platform (MEWP);
- Operative transport vehicles; and
- Delivery vehicles.
Schemes taking place at the Friarton Bridge structure such as the above require site compounds. These compounds will be constructed at the designated hard-standing access point present at the northern extent of the structure. At the southern extent, site compounds are present beneath the structure at the southern box girder access point. In both instances, site compounds are present beneath the structure, with an approximate 10-20m coverage outwith the structure boundary.
Construction is currently programmed to take place in September 2025 with works anticipated to last for approximately three to five months in total with sporadic working expected. Works will take place during daytime hours.
The proposed works will take place within the box girders of the structure and; therefore, no traffic management (TM) will be required for the scheme.
Location
The M90 Friarton Bridge structure is located within the city of Perth, Perth and Kinross with the works entailing walkway replacements within the box girders within the bridge structure itself. The two end points of the structure can be found at the approximate National Grid References (NGRs) detailed below. The scheme location is illustrated in Figure 1: Scheme Location:
- Northern end point: NO 13266 22102
- Southern end point: NO 12769 21171