Eastgate and Chester City walls

Eastgate and its world-renowned clock

Eastgate and its world-renowned clock

Contact

Fay Newham. Ramboll

Fay Newham

Project Associate
M: +44 7918 054 814
Paul Maddison. Ramboll

Paul Maddison

Principal Structural Engineer
T: +44 7870 808 343
 

Chester’s most iconic heritage asset, Eastgate and its world-renowned clock; the second most photographed clock in the UK after Big Ben, was reopened in 2015 following almost a year conservation and extensive repairs led by Ramboll’s conservation engineers.  The project was funded by Cheshire West and Chester Council, who recognised the important value of the site for its local economy.

Chester City Walls are Roman in origin but largely post-medieval where now visible above ground, and form an almost complete circuit of approximately 3km around the former medieval city.  The ancient defensive walls and the ramparts on which they sit are designated a Scheduled Monument, whilst many of the gates and towers are Listed Buildings. 

Constructed in 1768, the Grade I listed Eastgate replaced previous gates and formed the main entrance to the city. It comprises a sandstone archway over the carriageway with small pedestrian archways to each side, and further small arches to the North and South used as shops. Its wrought iron clock tower, erected later, was designed by architect John Douglas to celebrate the diamond jubilee of Queen Victoria. 

Conservation approach

Good conservation practice was followed using traditional materials where possible and modern materials only where appropriate. Minimising ongoing maintenance and improving access to the site’s 1000’s of visitors were also important considerations which had to be balanced with the conservation needs. 

Laser scanning was carried out before work started to create a 3D survey of the structures and adjacent buildings. This helped with understanding the geometry of the Walls, which in turn informed the design and planning of the works. The survey was used as a basis for tender drawings and created an important record for the future. When additional arches supporting part of the Walls were discovered within adjacent buildings to the South, and areas of Roman construction found within the core to the North, these were added to the records by updating the laser survey.


3D scan and modelling by Russell Geomatics

Repairs Summary

Extensive repairs of the ironwork and masonry at the Eastgate were necessary due to corrosion of the ironwork, water ingress into the deck and physical damage to masonry at low level whilst the adjacent sections of the City Walls had to be stabilised and repaired, following years of water ingress and progressive movement.

Work included; 

  • replacing the voided core of the wall caused by water ingress 
  • attempting to halt movement along this stretch by slightly adjusting the centre of gravity of the wall
  • relaying the existing stone paving on a new waterproofing layer
  • improvement to drainage to minimise future water ingress 
  • a new paint system applied to the ironwork following corrosion and breakdown of the system installed a decade earlier. 

Stabilisation work

Following a previous risk assessment of the whole of Chester City Walls  a detailed investigation of the north of Eastgate site was undertaken by Ramboll. This identified that the inner face of the wall in this location appeared to lean outwards, with corresponding defects in the wall-walk. After a period of monitoring, some propping was installed. Excavations and investigations of the wall core revealed extensive internal voiding and fissures, with slumping of the outer face into the core (Fig 1). This created an overall rotation of the wall outwards. With the inner leaf founded directly over the Roman rampart, underpinning of any sort was not an option. Therefore the design philosophy adopted was the adjustment of Wall’s centre of gravity to reduce overturning (Fig 2).

Archaeological work

Previous archaeological investigations on a section of the Walls to the North of Eastgate assisted in understanding the existing masonry structure. Temporary backfill with loadbearing polystyrene was undertaken whilst consent was gained for the proposed works, which included the permanent masonry repair to help prevent further rotation of the structure. All excavation within the Walls and to their foundations had to be carried out by archaeologists, with appropriate access and propping to the inner and outer leaves provided by the main contractor. 

Whilst most of the core was found to be relatively modern material, a small area of Roman wall was located. This section was carefully protected, and left in situ within the new core work.

Repairs

Masonry 

Masonry repairs to the Eastgate arch comprised removal of redundant fixings, stone indents to damaged/eroded masonry, repointing and gentle removal of algae. More extensive cleaning was considered and rejected because of the very soft and porous nature of the sandstone. It was discovered that several of the dentils had previously been replaced in timber. New stone was cut to replace these, fixed with stainless steel dowels. 

Bridge deck

The existing bituminous surfacing was opened up and it was discovered that a mass concrete slab had previously been cast over the archway. This was repaired and used as a base for a spray-on waterproofing system. New stone paving was laid over to improve the appearance of the deck. The fixings to the backstays for the wrought iron railings were improved at the same time.

Specialist ironwork

Specialist repairs carried out on the Eastgate clock included a complete repainting of the decorative wrought and cast ironwork of the clock and supporting structure. The existing paint system had reached the end of its life, with cracking allowing water to gather at connections and decorative features, causing corrosion. Previous poor-quality repairs to the ironwork were replaced, and the original paint scheme reinstated, including gilding. 

The existing paint systems were sampled and analysed for compatibility with proposed systems. The existing paint was found to have broken down to such an extent that most areas required extensive cleaning and preparation. Bituminous finishes had previously been used on some areas which bled through trial areas of primer, so these areas had to be removed back to bare metalwork, together with all corroded areas. In general areas were repainted in the same colours, but paint sampling to the cast iron panels around the clock dials revealed a previous colour scheme, which was then followed. Gilding was carried out by a specialist contractor using hand applied gold leaf.

Anti-climb plates had been fitted to the top of pillars, but this had exacerbated corrosion of the ironwork, so these were removed and new anti-climb collars installed.

The cast iron panels surrounding the clock dials were heavily corroded and cracked. The panels were repaired by screwing plates across the cracks from the rear, so that they were concealed from view. Further investigation revealed timber and fillers had been used in previous repairs, so they were replaced in traditional materials.

Archive drawings of some of the ironwork showed the original design intent for some of the missing decorative features. Blacksmiths forged new details based on the archive drawings and replaced the poor-quality replicas. However, where features were missing but the original design intent was not known, these were not replaced.

Specialist clock repairs

The famous clock dates back to 1897 and comprises 4 cast iron glazed skeleton dials. In need of some renovation, the original manufacturers JB Joyce & Co, cleaned, repaired, repainted and provided new movement mechanisms where necessary. whilst the clock was off site they fitted temporary hands outside the scaffold wrap and connected it to the existing mechanism, so that the hands continued to tell the time on a printed face for the whole project.

Water management

Minimising water ingress was critical to the ongoing preservation of the Walls and the Eastgate arch. At Eastgate slot drains with bespoke cast iron covers were introduced to collect water spilling off the deck. South of Eastgate there were severe problems with water entering into an adjacent shop and within an arch beneath the wall-walk. Existing drains passing within the Walls were removed, replaced by new pipes mounted on adjacent buildings, and waterproofing was installed beneath the wall-walk. North of Eastgate the wall-walk paving was relayed to give positive falls away from the adjacent buildings, with new slot drains introduced and waterproofing installed beneath the wall-walk.

Access improvements

Some of the paving was replaced with tactile paving, additional handrails added to steps and the wall-walk profile was smoothed, improving access for visitors.

Site management

The difficult access, linear nature of the site and the need to minimise disruption to the busy city centre called for a creative and collaborative approach, careful planning and management of the renovations.

An image of Eastgate was printed onto a scaffold wrap to the main elevations, to hide the works and maintain the appearance of the main street. This proved almost as popular a photographic subject as the real thing.

Ramboll

Ramboll
240 Blackfriars Road
London SE1 8NW
United Kingdom
Tel:+44 20 7631 5291
Fax:+44 845 299 1610

Mail: london@ramboll.co.uk

Company registration

Company registration

Ramboll UK Limited. Registered in England & Wales. Company registration no. 03659970. Registered office: 240 Blackfriars Road, London SE1 8NW


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