During a major initiative to remove electricity transmission lines impacting some of the most scenic landscapes across Scotland’s National Parks, our temporary bridging solutions played their part in enabling the works.
metre-long temporary bridge
tonne weight limit
weeks in place
In 2012, Ofgem announced plans for a £500million fund to assist GB Transmission Owners in mitigating the visual impact of existing electricity infrastructure on nationally designated landscapes. Project VISTA (Visual Impact of Scottish Transmission Asset) is to play a key part in enhancing these designated landscapes within the north of Scotland transmission network.
As part of Project VISTA, Principal Contractor Morgan Sindall Infrastructure is engaged on a contract for SSEN Transmission to remove two overhead power lines from Killin to Inverarnan and St Fillans substations. The overhead power lines will be replaced with new underground cables buried in uPVC ducting, installed by open cut trenching technique and by horizontal directional drilling (HDD) under the River Dochart. Following energisation a total of 31 redundant steel towers will be dismantled and removed.
Given the rural nature of the project and the resulting site constraints, part of these works is being facilitated through the installation of our 45-metre-long temporary bridge.
Constructed using the modular Mabey Universal bridging kit, the bridge has been designed and built to divert heavy construction traffic away from the village of Killin in the Loch Lomond and The Trossachs National Park, avoiding a narrow historic bridge which attracts thousands of tourists to the area.
We were initially approached by Morgan Sindall Infrastructure Scotland and its consultant, Baker Hicks, two years ago at the early planning stages of the work, when it was seeking competitive bids for the supply of a heavy duty access bridge to carry construction traffic up to a 55 tonne weight limit - including cable drum trailers and tractors - crossing the River Dochart.
As part of the liaison process involving the National Park as well as SSEN Transmission, we were able to illustrate the proposed installation process using time-lapse video footage from previous projects.
With abutments already built by Morgan Sindall to the designs of Baker Hicks – a Morgan Sindall group company - using a combination of reinforced concrete and Legato blocks, engineers took just three weeks to assemble the modular Mabey Universal Bridge sections and launch them using a 3600 excavator already on site. The completed 45 metre span bridge features an extra wide 4500mm clear road width and is one of the largest such structures deployed in the UK over recent years.
Our temporary bridge is expected to be in place for 62 weeks. The current work in progress at Killin is the third phase of VISTA projects Morgan Sindall Infrastructure has undertaken, with 15km of transmission lines already moved underground in the Cairngorms and three 1500m long stretches addressed near Sloy.
As a contractor covering a wide range of project types, we’ve worked with Mabey Hire on many occasions in the past. There are very few competitors who could have supplied the size of bridge required for the Killin VISTA project. The bridge was essential to minimise the amount of construction traffic travelling through the area, which would have caused disruption to Killin residents. We also had to consider the landmark Dochart Bridge, which is a single lane bridge measuring some 70 metres long. This bridge draws a lot of visitors and tourists, which would have made risk management more challenging. Mabey Hire shared its time lapse footage of past installations with the project team here during the tendering phase, which was very insightful, and the Mabey Universal bridge installed over the river has been specified to cope with heavy construction traffic, including low-loaders and the cable lorries. The work has gone well.
Our engineered solutions range from standard designs to major projects, through to emergencies. We can also offer an end-to-end service from design and supply through to installation and removal.
We can work with you from initial concept temporary works design through to project completion, across all aspects of temporary works.
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