Protecting & Conserving Heritage

Grade II listed Farringdon station building was built in 1865 and modified in 1922. This case study outlines the heritage features that were preserved during its redevelopment, the design challenges faced and best practice for future projects.

Protecting and enhancing cultural heritage formed one of the Thameslink Programme’s nine sustainability objectives and for the Farringdon Station the most significant impact of the work was due to the importance of the building’s heritage. The building is Grade II listed, but railway stations in Greater London are under the direction of English Heritage (EH) and therefore the determination process is the same as for a Grade I listed building. The work that was carried out with regards to the Historic Environment helped the project to score 100% in this section of the CEEQUAL submission whilst also setting standards for best practice across the programme.

Firstly, new planning permission and listed building consent for the listed parts of the site were required for any new additional work scope or changes to the approved design. It was necessary to obtain three very significant additional consents in the course of the project for the Turnmill Street concourse, changes to the new Integrated Ticket Hall façade and for the extensive works to the existing London Underground station building.

By July 2011 300 planning submissions were identified for the Farringdon project (including applications to discharge planning conditions). Only 65 of these submissions were related to the Transport and Works Act Order planning and listed building consents and the rest were as a result of subsequent changes in scope, design and temporary works and a project workload and resource requirement that was not originally fully anticipated. As a result the project recruited a town planning and heritage specialist resources into its consents team, in addition to those originally envisaged.

In addition to this the project programme was extremely challenging due to delays in the completion of the design, the timescales for obtaining these planning requirements, including three new significant planning and listed building applications, and severe compression of the project programme. In response, the consents team implemented best practice from specialist experience of other recent major heritage and railway projects including, in particular, Channel Tunnel Rail Link St Pancras, Crossrail and Kings Cross.

The consents team was also responsible for compiling statements of significance relating to the importance of the heritage fabric, undertaking impact assessments and working with the contractor to write method statements, all in support of the listed building consent applications. This was undertaken by the Farringdon Station project as best practice and has subsequently become a requirement of Planning Policy Statement 5.

Heritage features preserved

In order to minimise the effect of these works, Network Rail agreed with London Borough of Islington (LBI) and English Heritage (EH) to undertake the following to protect areas of architectural or historic importance including:

Sympathetic design

The new Turnmill Street entrance and concourse was designed to be independent of the existing station and composed of steel and concrete to minimise alteration to the adjoining listed train shed walls. The scheme augments the historic station and adjacent conservation area while retaining its own character and identity.

Retention, reinstatement and repair of heritage features

The retention of the historic arches leading from platform 1 to the new concourse removing the need for them to be demolished and rebuilt. The repair of faulty and leaking guttering that was allowing water ingress into the heritage structure and causing it to decay. The reinstatement of the historic shop fronts which date from the 1920s following their temporary removal to allow the underpinning of the station frontage.

Salvaging and reinstatement of materials

In accordance with good conservation practice bricks were salvaged from any demolition works for onsite reuse. The stone insets inscribed “Station Chambers – 1932” located on Turnmill Street were kept and instated in the new Turnmill Street Concourse building. The original fireplace and overmantle (dating from around 1922) located on the first floor of the London Underground station building was restored and reinstated close to its original location. In recreating the station’s original external appearance, Network Rail carefully removed, salvaged and ultimately reinstated all suitable external glazing.

Recording

Detailed records were taken to be used in designing and manufacturing ‘historic’ copies which, when installed recreated the station’s original external appearance.

Design Challenges

Delivering a sympathetic design that met heat retention regulations

One challenge that the team faced was delivering a design that met Part L of the Building Regulations through various heat retention methods whilst remaining sympathetic to the heritage asset. Network Rail commissioned a carbon study, which analysed the existing station entrance building’s thermal and carbon output based on a number of scenarios.

The carbon model study identified a projected improvement of 9.02 kg/ CO2 per square metre per metre which is the equivalent of approximately 4.5 tons of carbon per year being released into the atmosphere. Through extensive consultation with the consent granting bodies and having successfully addressed the conflicting requirements of heat retention and alterations to a heritage asset, Network Rail was granted planning permission and listed building consent for its works to the Station Entrance Building.

The approved design preserves the building’s historical integrity whilst managing to deliver a compliant building which is fit for purpose and demonstrates a commitment to Thameslink Programme’s energy and carbon objective.

Best practice

The project undertook baseline surveys and historic recording reports throughout the site as best practice. Given the sensitive and busy nature of the area, the project team made every effort to consult with all relevant parties and throughout construction works station information boards were used to show the original and current station.

Heritage exhibitions were held in the shop fronts once the London Underground station reopened. The exhibitions was named ‘Farringdon: past, present and future’ and was a free public exhibition to mark restoration of the station that explained the changes that had been made and how the project had used traditional building materials, such as lime plaster containing horse hair, and methods in order to restore the old shop fronts.

The best practice approach employed at Farringdon in repair and alteration work to the listed building was based on replicating traditional construction methods. This included constructing traditional brick arches which are no longer widely used in the construction industry.

The Heritage Advisor prepared detailed design drawings for the new brick arches which included setting out information, sizes and construction information at full size to assist the bricklayers. The specialist masonry repair subcontractor provided bricklayers who were keen to practice and learn about these traditional construction methods. Site workshops were held to discuss the design and construction methods and monitor and assist during the construction of each arch.

Constructing the new brick arches also proved to be very successful because of the enthusiasm of the bricklayers and willingness to learn, providing detailed design information, and taking time to prepare mortars which matched the originals and sourcing second hand bricks which matched the originals. The willingness to use traditional methods rather than false arches with modern lintels was critical. Adopting traditional brick arch construction provided a valuable opportunity for both experienced and apprentice bricklayers to gain valuable experience of this traditional, now occasionally used method.

Further information

For more information on this Learning Legacy case study please email contact@thameslinkprogramme.co.uk