Site investigations have begun at Dukes Meadows for the 'iconic' promenade bridge
Cllr John Todd observes the start of the site investigation
The first step towards the iconic new footbridge which will link Dukes Meadows with the Thames Path, has been taken this week as contractors begin surveys of the area.
An archeological survey was carried out in the area adjacent to Thames Tideway rowing club, close to where the bridge will be located. A munitions sweep was also carried out for any unexploded World War 2 ordnances and was found to be clear.
Chiswickw4.com visited the site with councillor John Todd, who is chair of the Barnes Footpath Project Board.
Heavy equipment has now been brought on site to bore down into the ground in a process known as 'cone penetration testing ', (see picture below) with a rig known as a 'bog skipper'.
This is an electronic technique which is aimed at profiling the soil types in advance of the pile foundations. The equipment is boring down around 20 metres below the ground and the information will be used to create a profile of the soil types. This is mainly a marine silt, very sandy and not very cohesive. The information will be relayed to the pile designers.
The tracked mounted CPT is ideal for soft or boggy ground conditions due to its large footprint and low bearing capacities.
In technical terms, it is described thus: "Cone penetration testing (CPT) is an in-situ test whereby a cone penetrometer mounted to a series of steel rods is vertically pushed into the ground. Hydraulic rams on the CPT rigs push the cone penetrometer at a constant rate of 20 mm per second to depths of up to 100 m."
Geologist James, who is part of the site investigation team contracted by the structural designers, said they were carrying out a variety of tests of the strength of the soil, taking geotechnical and contamination samples.
John Todd commented: "It's taken a lot of negotiation to get to this significant development. If the tests are all satisfactory we can then start to proceed with the bridge."
Hounslow Planning Committee approved the application for the proposed new footbridge beneath Barnes Bridge in February 2018.
The walkway is part of the overall regeneration plan for Dukes Meadows.
The main benefit to the public is that that pedestrians will no longer have to divert up Dan Mason Drive and The Promenade and away from the river while walking on the Thames Path.
The design of the proposed new footbridge beneath Barnes Bridge was submitted by Moxon Architects. The design is for a curved structure which would sit below the bridge and link the Thames Path to Dukes Meadows.
The 'cone penetration' rig
When the consultation on the Dukes Meadows masterplan was being carried out, the pedestrian bridge was one of the items which rated most favourable feedback, indicating strong local support for the project.
The design is intended to maximise views of the river, with a meandering alignment to encourage views up and downstream as well as into the Dukes Meadows nature reserve.
Barnes Bridge at present
The project would use offsite prefabrication and river transport to reduce disruption and carbon consumption during construction.
Hounslow Council leader Steve Curran says; ‘Dukes Meadows is an incredible asset for Hounslow, achieving over 1 million visits per year. The new Dukes Meadows footbridge is an iconic structure that will no doubt add character to the area and, we hope, be appreciated for generations to come.’
Moxon is an international firm of architects with previous experience in building bridges. They were also involved in the design of the Taipei Museum of Art.
November 8, 2019