Progress reports

Weekend Road Closure Report 27-30 January 2017

 

Low loader

The footbridge over the rail line was lifted in at the weekend. It was fabricated and painted in West Lancashire and was delivered by low loader lorry to the Bridge Road site during Saturday 28 January.

 

The two reinforced concrete abutments had previously been constructed either side of the railway line, they are supported on 600mm diameter augered concrete piles.

 

Crane in position

A 300 tonne crane was set up on the North side of the railway line using outriggers and spreader plates to ensure its stability. The bridge was positioned on the existing road bridge.

 

There was a short wait for the pre-arranged railway “possession”, a period of several hours where no trains will pass. Network Rail were attending and gave the go ahead around 12.30am.

 

Bridge lift

Using a spreader beam and large straps passing under the deck, the footbridge was lifted from the lorry, up over the parapet of the road bridge and down into position on the two new abutments where it rests on thin “elastomeric” rubber bearings and is secured by bolts.

 

 

 

Footbridge in place

The railway footbridge awaits final adjustments and the installation of interior bolted steel panels and lighting units, but is otherwise substantially complete.

 

Note there are fixing points along the top edges of the footbridge parapets to allow for the possibility of a canopy in future if required.

 

Weekend Road Closure Report 18-21 November 2016

Good progress was made on site during the weekend road closure, in spite of some challenging weather over the weekend.

Activity on Countess Wear Bridge
Activity on Countess Wear Bridge

Countess Wear Flood Relief Bridge

The critical task for this weekend was the completion of the concrete repairs to the soffit (this means the underside of the bridge deck) of this reinforced concrete structure. This work had to be done during traffic-free conditions, because otherwise the small vibrations from moving traffic would have detrimentally affected the bond of the repair material to the existing structure. This work was started during the previous weekend closure of 28-31st October, but had to be programmed over 2 separate weekends due to the combined length of time of applying the material, and the required time for the material to cure. A description of this work was included in the previous weekend closure progress report, should you wish to find out more detail.

Spraying of concrete repair material began on Friday night, and into Saturday morning. There was a short break due to the incoming tide in the morning, and the spraying was completed on Saturday. Did you know that the River Exe is tidal at Bridge Road, up as far as the weir near Salmonpool Lane? The Countess Wear Flood Relief Channel discharges to the River Exe just downstream of Bridge Road, but this means that at high tides, the water washes back up the Flood Relief Channel. The site team have to work around twice-daily tidal inundations to this structure.

Alphin Brook Culvert

To accommodate the widening of Bridge Road on its west side, an L-shaped reinforced concrete retaining wall was designed to sit above the upstream end of the culvert. Previously there was an earthworks slope from the edge of footway, down to the culvert headwall. The retaining wall allows for the new footpath to be pushed outwards where the slope previously existed. This retaining wall in designed in 3 sections.

Reinforcement cage being lifted in during the early hours of Saturday
Reinforcement cage being lifted in during the early hours of Saturday

Before the weekend, the Contractor was unable to access the northern section because of current traffic management layouts with 2 lanes of traffic over the bascule bridge. Because this structure is so close to the bascule bridge, the temporary traffic lanes could not be laid out with any sharper change of direction, to avoid the footprint of this retaining wall. During the weekend road closure, the temporary footpath was re-routed further away into an area that was being used as a traffic lane, and the temporary footpath could be excavated.

Prior to the weekend, the reinforcement cage (this is the network of steel bars that are used to strengthen the concrete) was built in a nearby location. Once the excavation was complete the cage was lifted into position, and formwork was erected (this is the timber panels which create the final shape of the concrete structure and they form a mould for the concrete to be poured into).

The excavation started on Friday night, and concrete was being poured on Saturday morning. Once the concrete had set firmly enough, the formwork could be removed, and on Sunday fill material was brought in to raise the ground level above the wall base, and the footpath route was re-created ready for the road to be re-opened on Monday morning.

Rail Bridge South abutment – during the concrete pour
Rail Bridge South abutment – during the concrete pour

Railway Footbridge South Abutment

Because the proposed new fourth lane of traffic will take up the space that was occupied by the foot/cycleway over the railway, a new separate pedestrian/cycle bridge is being provided alongside the existing road bridge supported by structures called abutments. On Saturday, the south abutment base was poured.

This was done during the road closure period to allow a concrete pump and the concrete delivery trucks to access the working area without conflicting with traffic.

Pavement reconstruction either side of the rail bridge
Pavement reconstruction either side of the rail bridge

Road pavement

Four separate areas of road construction were rebuilt during the weekend. The vast majority of Bridge Road carriageway area will be re-surfaced before the end of this project – the top layer of road pavement is called ‘surface course’ and in this case will be 40mm thick.

 

However, where structural failure of the pavement has been identified because of visible cracking or settlement, these areas are being excavated to nearly 0.5metres deep and entirely reconstructed. Four of these areas were tackled during the road closure.

Pavement reconstruction over Countess Wear Bridge
Pavement reconstruction over Countess Wear Bridge

 

Our next weekend road closure will take place in the New Year and will be advertised as usual, via signage two weeks in advance and via a news update on the Bridge Road webpage.

 

 

 

 

 

Weekend Road Closure Report 28-31 October 2016

The critical task for this weekend closure was the concrete repairs to the reinforced concrete Countess Wear Flood Relief Bridge, a critical piece of infrastructure to both the flood defences and highway network of Exeter.

The structure was suffering from the ingress of water and road salts, resulting in the corrosion of steel reinforcement and deterioration of concrete (see ‘before’ photograph in the previous progress report).

Photo 1
Photo 1

 

The concrete was first removed through the process of hydro-demolition, this happened in advance of the weekend closure. Once this was completed equipment known as “sacrificial anodes”, were fixed in place to help protect the steel reinforcement from future corrosion.

 

 

Photo 2
Photo 2

Looking at Photo 2 you can see that the extent of the removal of defective concrete extends across the full width of the bridge deck which in turn affects the full width of the highway above.

With the anodes fixed in place, concrete was sprayed from a hose onto the structure. One of the critical elements to this repair was ensuring a good bond between the old and the new, in order to achieve this traffic had to be kept off the structure until the concrete had cured sufficiently – as a guideline this takes approximately 36 hours but is dependent on temperature. Moving traffic creates small vibrations in the structure which would have adversely affected the bond.

 

Photo 3
Photo 3

Photo 2 above and photo 3 show the before and after images for the concrete repair on one of the five bays under the Countess Wear Flood Relief structure.

 

Bus layby surfacing – There were many other activities which could be worked on while the road was closed. One of these activities was the surfacing of the recently modified bus layby at the northern end of Bridge Road.

 

Photo 4
Photo 4

Photo 4 shows the surfacing works of the layby partially complete. The sign posts in the area are due to be replaced with new posts, which were not available in time, so unfortunately not all of the footpath areas could be completed during the weekend. However many of the barriers protecting this area of work have now been removed and we thank all neighbours and bus users for their patience and co-operation with this work.
A protective layer of concrete was placed over the newly waterproofed deck of the Exe Channel Flood Relief bridge as well as the Alphin Brook culvert. These works were also programmed for a weekend closure due to the additional working space required, as well as the high volume of disruptive construction traffic involved in these operations, including concrete wagons and heavy plant.

Photo 5
Photo 5

The protective layers of concrete can be seen placed in Photo 5 showing the Exe Channel Flood Relief Bridge.

Finally other tasks that were carried out during this weekend closure included – duct crossings for the installation of new utility services or diversion of existing services; the removal of some sections of the old Vehicle Restraint systems or crash barriers; and the removal of old lighting columns over Countess Wear Bridge which will enable work on the new cantilever beams for the footbridge to be progressed.

 

Weekend Road Closure Report 24-25 September 2016

Firstly, thank you from the Bridge Road site team for your patience and understanding during these essential closures.

Hydrodemolition mini-rig
Hydrodemolition mini-rig

One of the key activities was the demolition of the west side of Countess Wear Flood Relief, with the use of highly pressurised water to remove the concrete that forms part of the structure but leaving the reinforcement within the concrete intact, a process called “hydrodemolition”.

 

 

 

The hydrodemolition involved removing the full depth of the bridge deck over an 800mm wide strip which will allow new steel to be fixed into position alongside the existing steel, facilitating the extension of the structure westwards several metres to cater for the additional traffic lane and the new footpath / cycleway.

Hydrodemolished deck
Hydrodemolished deck

 

 

Although the bulk of this has been completed, this work is continuing overnight this week. This side profile of the hydro-demolished deck, through the debris netting, was taken at the very start of the hydrodemolition process.

 

 

 

Another key activity was the full reconstruction of road, firstly in areas where structural work had previously taken place, but also in areas that have been identified as reaching the end of their design life and have started to fail.

Carriageway excavation
Carriageway excavation

 

This operation involves excavating the existing road down to formation depth, placing a layer of well compacted stone, followed by a number of layers of Bituminous material, ready for the road to be trafficked again when the road re-opened on Monday morning. This photo shows an area of carriageway being excavated ready for new material to be laid because this area of the existing road was showing sign of failure.

 

Roller compacts newly-laid material
Roller compacts newly-laid material

 

Due to the number of different layers and cooling time required between the layers it is not possible to do this operation in a single day. This photo shows the paver laying the final parts of the upper base layer and a roller compacting the newly laid material, to the right of the picture you can see the newly installed VRS stanchions being allowed to cure ahead of the road re-opening.

 

 

VRS barriers
VRS barriers

 

Vehicle restraint systems (VRS), more commonly known as crash barriers, were installed in a number of locations along the length of Bridge Road, with the need to divert services in some locations to facilitate the concreting of the barrier stanchions, following this the barrier’s longitudinal beams had to be fixed in place and the concrete allowed to cure sufficiently ahead of the road opening.

 

 

Due to the high volumes of heavy plant and construction traffic throughout Bridge Road, the traffic management had to be altered to allow additional working space in a number of key areas. At the same time, a safe route had to be maintained for pedestrians and cyclists, while also ensuring that the site layout could be accessed by emergency service vehicles, with an ambulance being escorted swiftly through the site at 11am on Saturday.

Countess Wear Bridge parapet
Countess Wear Bridge parapet

The weekend programme also included the erection of scaffolding on Countess Wear Bridge ready for the archaeological recording of the listed stone structure, ahead of the partial demolition of the triangular cutwaters in preparation for installing the new Countess Wear Footbridge. This photo shows the bridge parapet which runs roughly down the middle of the photo, with the counter weight water towers on the right hand side, and the working platform over the River Exe on the left hand side of the bridge parapet. This working platform will be used to take the archaeological recordings of the stone work and will also be needed during the demolition of the masonry cut waters.

 

With work nearing completion on the east side of the carriageway, just south of the canal bridges, contractor Lagan has opted to alter the traffic management layout by swapping traffic to the west side and temporarily diverting pedestrian and cycle traffic onto the road. This has required the removal of kerbing and pedestrian barriers at this location. This arrangement has provided the space required to begin work on the Alphin Brook culvert and Exe Channel Flood Relief Structures on the west side. Once the weekend closure work was completed, the traffic management then had to be altered a final time to ensure the road was once again ready to carry two lanes of live traffic.

In order to minimise disruption to users of the highway, essential work by other contractors has been co-ordinated to take place within the road closure, such as essential road maintenance to the north of the scheme.

 

Weekend Road Closure Report 10-11 September 2016

Weekend Road Closure Report 10-11 September 2016

Bridge Road was recently closed for the weekend 10-11 September, to allow the Contractor to undertake certain tasks which required the full width of the road.

A key activity was the waterproofing of Countess Wear Flood Relief Bridge, a 1960s structure in poor condition – in outline this involved the following tasks:

Partly completed bridge movement joint
Partly completed bridge movement joint

Removal of the existing asphalt (tarmac).
Repair and testing of the reinforced concrete deck.
Preparation of the movement joints at each end of the bridge.

 

 

 

 

Preparing concrete deck and placing foamed concrete
Preparing concrete deck and placing foamed concrete

Excavation at each end of the concrete bridge to allow waterproofing here, backfilling with foam concrete.

Priming of the deck and spraying of the quick curing waterproofing product. Testing of the waterproofing and repairing any holes.

 

 

 

 

 

 

 

Services trench to North of Countess Wear Flood Relief Bridge
Services trench to North of Countess Wear Flood Relief Bridge

Additionally trenches were dug across the road in five locations to allow electricity and telecommunication services to be laid.

The contractor also took the opportunity to work on reconfiguring the bus stop at the North end of the site to allow for the final widened road layout.

 

 

 

 

 

Laying Asphalt
Laying Asphalt

Finally all the areas worked on were re-surfaced with new asphalt.

 

 

 

 

Apologies for any inconvenience caused by this road closure.

Please note the next road closure is scheduled for 24/25th September.

Progress report 2 – 26 April to 27 May 2016

Concrete sliced and dicedThe majority of the work on the Countess Wear Relief Bridge in the past month has been hydro-demolition – if you’ve passed the site in this time you may have noticed a blue tanker and a green tent. The operative working inside the green tent holds a high pressure water jetting gun; the water disintegrates the concrete but leaves behind the steel reinforcement. By removing strips in a grid pattern the concrete was broken into chunks.

In the early part of the month, following installation of a temporary steel crash barrier, the existing steel crash barriers on the approaches to the railway bridge were removed. Work has then started on excavating the embankment to the South of the railway line.

Kerbing and services work has continued at the north end of the site, including the removal of the island at the junction with Glasshouse Lane.

Work started this month on the Exe Channel Flood Relief Bridge, which is located between the canal and the railway; although you would hardly notice it from the road – the photo below gives a view from the flood channel to the south.A road to nowhere...

The eventual plan for the historic Canal Swing Bridge historic bridge is to rotate it by 4.2 degrees, which translates to around 1.6m at the “nose” end. This will allow a better alignment of the road as it passes over it, removing the “kink” on the south side and allowing two lanes of traffic to use this narrow bridge.

This rotation will require new foundations to support the bridge in its new position; this month we undertook some trial openings in order to gauge the space required for a mini piling rig to get in to drive new piles.

Read the full report here.

Progress report 1 – Start of works to 25 April 2016

Early work involved setting up the Traffic Management (which commuters will be familiar with), and the site compound area – these porta-cabins will be our home for the next year. Setup of the site offices

The bridge over the river Exe is called Countess Wear Bridge, and houses a healthy population of Soprano Pipistrelle and Daubenton’s bats. The bridge is an ideal habitat for them as in the evenings they can swoop down from their roosts to pluck midge larvae from the surface of the river. As part of the scheme we have provided enhancement in the form of artificial bat roosts. Because this is a historic structure these have been camouflaged carefully to match the stonework of the bridge.

Following this work, the footpath on the Topsham side of Countess Wear Bridge has been removed in preparation for the new kerb line. To enable the widening of the road, the kerb line is being moved further to the East, nearer to the bridge parapets. Much of the work to date has been on diverting and re-laying the services on this side of the road; this is currenyly ongoing. We have a water main, telephone and fibre optic cables, electricity supply for the street lighting, and further telecommunications ducts to fit in a reduced space. The picture below gives an idea of the complexity:

At the North end of Countess Wear Bridge work has started on laying kerbs; however thAccess track under Countess Wear Flood Relief Bridgeis has necessitated the removal of some buried concrete steps which date from the 1930s. At this time the bridge was significantly widened and the road level raised; these concrete steps stabilise the masonry parapet wall; but unfortunately occupy the space where our new kerb line should be. Therefore the upper part of the concrete steps has been broken out; this won’t affect the parapet wall as the kerbing will be supported by fresh concrete. This has enabled the start of the kerbing work.

Read the full report here.