Design Statement

for conservation, repair, restoration, and protective interventions

to Victoria Bridge, ,

(April 2021)

This design statement is written in support of a Listed Building Consent/Planning Application to carry out important repairs and conservation work to the Mar Lodge Bridge, Braemar. The property is situated over the River Dee, just west and upstream of the historic village of Braemar, in the heart of the Cairngorms National Park.

Background

Mar Lodge Bridge (sometimes referred to locally as ‘the White Bridge’) was built in 1905 as the main approach to the Mar Lodge complex for Alexander Duff 1st and his wife, HRH Princess Louise. The bridge is Listed Category B (ID ref 333976). In 1995, the estate was acquired by the National Trust for Scotland,

Severe flooding of the River Dee in late 2015 badly scoured the site of the bridge, which also threatened to undermine its north pier, leading to collapse. The NTS, therefore, commissioned a specialist investigation into the condition of the bridge. This Planning Application for proposed repairs and conservation is the outcome of that investigation. The interventions are deemed important, ‘fairly urgent’, and much-needed.

Design approach

The approach from the outset has been to conserve the bridge based upon a thorough understanding of the structure’s history, design and construction, use of materials, performance, and risk. The philosophy is focused upon minimum intervention necessary to secure its long-term future.

The design approach is taken forward by a multi-discipline, engineer-led Design Team, and is backed by several key reports and analyses :

Historic Metalwork Conservation Company Ltd ‘Victoria Bridge’ (Sept 2019)

NBPA, ‘Conservation Statement and Heritage Impact Assessment’ (NBPA March 2021)

Allen Gordon Ltd ‘Engineering Conservation’ (April 2021)

Landcare NE, ‘Otter and freshwater pearl mussel survey and Bat PRA’ (April 2021)

Scottish Lime Centre Mortar Analysis

Built heritage will be protected through the replication of original materials and detailing, including mortar analysis information relating to stone bonding. Natural heritage will be protected by executing the recommendations of the ecologist for protected flora and fauna species such as bat, otter,red squirrel, rare birds, freshwater pearl mussels, twinflower and serrated wintergreen etc.

Since the bridge is sited in an area identified by SEPA as a ‘medium flood risk’, a Flooding Risk Assessment by Allen Gordon Ltd is included to assess the permanent impact of the works, such as improving the drainage off the deck surface, and also the temporary risk caused by the works programme.

Climate change predictions have heavily influenced the design approach and it is proposed to make the bridge, which has been stiffened by later iron plates and cement mortar, more flexible and dynamic to cope better with future extremes in weather, i.e. temperatures, flooding, wind.

Proposals

The proposed works are focused upon (a) protecting the bridge north pier from further erosion by creating a sacrificial concrete boot; (b) rebuilding the south abutment masonry parapet and gate piers with lime mortar and flexible jointing; and (c) cleaning, repairing and re-painting all ironwork, i.e. girders, balustrades, decking, gates, and archway, including flexible joints at key movement points.

Justification

The works to repair and conserve the bridge have been promoted by the structure’s owner, but has been made urgent and important by the last spate in 2016. Works to protect the north pier is now deemed ‘essential’ to prevent the bridge from sudden collapse; the need to rebuild the south west abutment wall is driven by health and safety requirements; and the repairs and repainting of the ironwork is deemed critical towards sustaining the structural integrity of the bridge.

Consultation

The proposals have been compiled following consultation with Local Planning Authority, including specific guidance within Pre-Application advice note ENQ/2020/1789 (Case Officer Jan Regulski). This process has included consultation with the Council’s Built Heritage and Environment Teams, plus the Cairngorms National Park Authority, the Historic Environment Scotland Area Inspector, and the NE Scotland Biological Records office.

It is noted that the CNPA do not intend calling in the application.

Policy Guidance

The proposals have been put forward following policy guidance outlined in the Cairngorms National Park Local Development Plan 2021. The proposals particularly respond to policies relating to Policy 2 ‘Supporting Economic Growth’ and Policy 8 ’Open Space, Sport and Recreation’ because the focus is upon retaining the bridge as an existing resource and core path access point for visitors’ active travel (e.g. walking, cycling, horse- riding). Whilst work is underway (scheduled as autumn 2021) such visitors will be directed to an alternative route, which is indicated within the application as part of the applicant’s 4-month temporary visitor management plan. The proposals seek to respond directly to climate change predictions, such as increased temperature swings and more frequent flood occurrences. Retention of the bridge is important in supporting Policy 5 ‘Landscape’ and Policy 9 ‘Cultural Heritage’, since its retention and repair will protect current amenity, enhance the existing landscape and secure its cultural value, particularly its royal association.

The proposals are firmly guided by Policy 9.1 ‘Listed Buildings’, which seeks to ensure that the distinctiveness and special qualities of the bridge, such as its latticed ironwork and rolled or embossed lettering, are preserved and enhanced. In this respect, the approach conforms to Managing Change in the Historic Environment ‘Engineering Structures’ Guidance 2010. Further technical advice and knowledge has been gained from HES various publications : ‘Managing Change in the Historic Environment: Use and adaptation of Listed Buildings’; ‘Managing Change in the Historic Environment: External walls’; ‘Managing Change in the Historic Environment: Works on Scheduled Monuments’; ‘Scotland’s Listed Buildings guide for owners and occupiers’; ‘TAN Preparation of Lime Mortars’; and ‘TAN Stone masonry skills and conservation’ ; ‘HES INFORM : Ironwork’; and HES ‘Advisory Standards of conservation and repair for the historic building environment in Scotland’.

Natural heritage within the Cairngorms Special Protection Area, Mar Lodge Estate National Nature Reserve, and River Dee Special Area of Conservation is not directly affected by the bridge repair proposals, but the international and locally designated sites, as well as protected species and water quality clearly need protecting during the process, e.g. a works compound will be designated, and the bridge will be fully encapsulated to create a controlled environment and prevent pollution or contamination of the wider environment. If required, the project will have an Ecological Watching Brief during the period of site construction. A bespoke Construction Method Statement that is targeted at minimising the effects of the project upon the natural environment will be submitted to the Planning Authority once a contractor is appointed, prior to commencing works. The Statement will include prior consultation with SEPA, NatureScot, the Scottish Canoe Association, the Deeside District Salmon Fishery Board, and Aberdeenshire Flood Risk and Roads Teams. An application for in-river works will be made to SEPA prior to the works commencing.

There are no trees proposed to be affected by the project.

Timetable

Subject to Planning Approval and smooth tendering procedures, work is scheduled to be on site for 4 months Aug-November 2021.

The works are timetabled to try and strike a balance between (a) protecting the local summer economy and the prime breeding period for local wildlife, and (b) executing the works within a ‘weather window’ that is safe for workmen and conducive to the historic nature of the conservation works, e.g. suitable temperatures for painting and/or using lime mortar.

It is proposed that a photographic record of the conservation works be undertaken as the work proceeds.

Summary

Mar Lodge Bridge is an important historic and architectural structure that is currently at risk from erosion and corrosion and, therefore, in crying need of intervention. The need for intervention has been carefully considered with a conservation approach from outset, and the impact upon built heritage has informed the design process throughout. Concern for natural heritage is at the forefront of the works programme. On completion, the bridge will remain open for public use as a core path; albeit, there will remain a weight load limit for vehicles in order to avoid future damage to the structure. Following the works, the bridge and its repairs will be monitored by the client and the lead engineer.

By Dr Nick Brown BSc(Hons), Dip Arch, Pg Dip, PhD, RIAS, RIBA, RTPI, IHBC, FSAScot, MILM

NBPA/PB April 2021