Update on essential works A642: A642 Wakefield Road, Garforth. Proposed retaining walls, near Ringway. The existing retaining wall is between 0.5m and 1.2m in height and is constructed using 1m long concrete blocks (kerb stones) laid end to end (parallel with the road), with the first (bottom) row laid perpendicular to the road. The wall has been constructed without the use of mortar with all joints dry. The underlying ground conditions consist of loose uncompacted made ground of various materials. The retaining wall is currently failing and as a result, cracks have opened up in the footway above the wall, parallel to Wakefield Road, up to 500mm wide. The wall beneath the footway crack at this location is bowed and leaning past the vertical towards the field, resulting in a void behind. Also associated with the failing retaining wall are two areas of cracking in the highway. The embankment to the field is also settling. After monitoring of the footway and highway cracks, in early December 2012 it was decided to carry out some temporary works to support to the highway and highway retaining wall. The works comprised of driving 4m long, 0.5m wide sheet piles to approximately 2m below ground level, using the arm of a 20 tonne excavator, without the use of any specialist pilling attachments. Bulk bags of stone were then placed between the existing retaining wall and the piles to provide support and prevent mass failure of the wall. The remedial works are only a short term solution, providing temporary support to the highway, preventing complete collapse. Five different options were considered to resolved the problem, due to the various ground condition factors, time and occupation of the highway and existing services the below option was considered the most appropriate. King Post walls consist of drilling bores at centres along the length of proposed wall. Posts consisting of steel beams are placed in the bores and concreted up to the excavation level. Fabricated concrete panels can then be placed between the posts; the panels would have to be placed to a depth of at least 1.5m below the existing wall to provide sufficient support to the carriageway. The posts themselves will need to socket into weathered sandstone at approximately 8m below carriageway level. Prior to the final wall being constructed a temporary structure consisting of sheet piles need be to driven down to the bed rock to support the drilling plant for the King Post wall, this will also protect the existing statutory services which run along the footway. Due to the poor ground conditions the drilling rig will also need to be sat on a wooden mat to spread the weight of the machine, (6.3m long and 13.4t in weight) which will work from Wakefield Road. The closure of Wakefield Road is necessary due to the size of the machines, amount of materials required to carry out the works, i.e. steel columns 48no at 8m in length, a concrete batching plant plus concrete materials, water supply, cabins etc. plus space to unload and park vehicles engaged in the works. This will both protect the travelling public and workforce. Due to the length of the two sections of walls and space required to work safely the extent of the site along Wakefield Road is toward the maximum length allowed for two way traffic lights. In order for these to function correctly and prevent build-up of standing traffic becoming agitated Ringway must be closed. Two way lights will also hopefully assist the safe access for residents which have direct access onto Wakefield Road from within the traffic managed length of the scheme. These will operate on a ‘slave’ light and one way traffic sign as it will not be possible to see moving traffic from either end. The intention is to reduce the speed of Wakefield Road from the current 40mph to a 20mph limit. Unfortunately as with all major construction schemes there will be noise throughout the working day which will involve piling hammers and percussion drilling. Airborne dust will be kept to a minimum by water suppression. Diversions will be set up around the scheme on a like for like road basis, A63 Selby Road to A656 Ridge Road to junction 47 M1 and vice versa. However it is expected that locals will find and know other routes. UTC is aware of the scheme and will monitor traffic signals. Signs will be erected with regard to local businesses which will be affected by the road closure. There is also a press release which encourages locals to support these businesses. A personal visit will also be made to discuss the closure and works to all businesses between Main Street and the roundabout, including the various surgeries. Scheme is programmed for completion between 8 and 10 weeks, this depends on time that it will take to set up traffic management each day, drilling and pile production, repairs to existing footway and carriageway following the wall works. Commences Thursday 31st July, for the first 4 days temporary lights will be in operation 24hrs per day. From Monday 4th August the road closure will be setup and will operate between 07:00 and 19:00 Mon to Sat, from 19:00 this will then be changed to a system of two way signals till 07:00 and operate throughout each Sunday.
Posted on: Sat, 19 Jul 2014 07:25:29 +0000
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