A68 Station Road Bridge Refurbishment

1.0 Brief Description of the Works

Works were undertaken to refurbish Station Road Bridge in Jedburgh, which carries the A68, the main arterial route through the town. The bridge was constructed in 1926 and is a Category B listed structure.

Following extensive consultation with the local community, including a 2 day public exhibition, a solution was developed by BEAR Scotland where a temporary bridge was installed across half of the carriageway, allowing the road to remain open while works continued below. This solution meant that closures of the A68 were limited to three weekends to allow the installation, movement and removal of the temporary bridge. The works were also programmed to avoid the main tourist season and major local events, including the Jedburgh Marathon. Consultation was also undertaken with the Historic Scotland, SNH and SEPA to ensure the proposed works were sympathetic to the surrounding area.

2.0 Client for the Works

The Client for the works was Transport Scotland (Trunk Roads Network Management)

3.0 Value of Construction Phase

£500k

4.0 Name of Contractor

BEAR Scotland Limited

5.0 Commencement of Construction & Duration

Seven weeks commencing October 2008.

6.0 Design Brief

The main works involved the replacement of the existing concrete protective coating and installing a concrete saddle with spray applied waterproofing to the main bridge deck.

7.0 Innovation Including Trials and Monitoring

Traditional construction methods would have involved a full closure of the A68 for up to 5 weeks. This was deemed impractical due to the lack of a suitable local diversion. The main diversion route for a closure at this location would involve a reroute of traffic over a length in excess of 30 miles, having a major impact on the local businesses, bus service and emergency service access. The installation of the temporary bridge allowed vehicle movements to remain, in the main unaltered.

8.0 Testing

Nothing specific to note.

9.0 Sustainability

As mentioned above a temporary bridge was installed to remove the need for lengthy closures of the A68. This also negated the requirement for the associated diversions. An extended diversion of 30 miles would have a negative impact on the local environment, increasing journey times, and leading to an increase in vehicle emissions.

10.0 Procurement Considerations

This scheme was built as of right under the 3rd Generation Term Maintenance Contract. Normally a construction value of £250,000 is set for as of right schemes but due to the number of unknowns associated with the bridge geometry it was agreed to carry out the works without a competitive tender process using the rates within the contract.

11.0 Site Supervision Issues

No issues. Construction phase completed on time and to programme.

13.0 Traffic Management / Special Requirements

Progress on the scheme was such that the temporary bridge was able to be removed two weeks earlier than originally programmed with positive feedback received from the local community and press. The refurbishment works have ensured the continued durability of the 80 year old structure, providing unhindered travel along the A68 for the foreseeable future. This scheme has recently been put forward for a Historic Infrastructure Award.

Back to Case Study list

A90 Hatton Bends

1.0 Brief Description of the Works

This minor improvement project is located approximately 13km south of Peterhead on the A90 Perth to Fraserburgh Trunk Road. The works consisted of a new off-line section of single carriageway north of Hatton, west of Cruden Water to west of the Auchiries South Junction, an overall distance of around 1km. This improvement included lengths of new side roads, construction of a new bridge over the Cruden Water and a footway along the south side of the A90 Trunk Road, demolition of the existing Midmill Bridge, associated traffic signing, temporary fencing, diversion and renewals of public utility apparatus, including a piled bridging structure over a Shell Oil pipeline, drainage, landscaping and accommodation works.

2.0 Client for the Works

The Client for the works was Transport Scotland (Trunk Roads Network Management)

3.0 Value of Construction Phase

£5.65m

4.0 Name of Contractor

Balfour Beatty Civil Engineering

5.0 Commencement of Construction & Duration

Commencement – 21 November 2005
Completion – 6 February 2007

6.0 Design Brief

The objective of the scheme was to improve the alignment of the existing carriageway.

7.0 Innovation Including Trials and Monitoring

as part of this scheme was the replacement of Midmill Bridge, a reinforced concrete and masonry arch bridge carrying the road across Cruden Water. Early in the design process the approach adopted was to maximum durability by constructing the arch in discrete interlocking precast concrete voussoirs and thus eliminate reinforcement entirely from the arch structure.

The road crosses the river obliquely and to maintain the spandrels parallel to the road a skew of 35° on the arch was required. Skewed arches pose a challenge as the geometry of the coursing of the voussoirs is extremely complex.

3D CAD modelling was deployed at the design stage to obtain an economic and buildable voussoir block that could be set out and placed on the barrel falsework requiring no more than conventional site skills and resources.

A single block type was designed for the arch and in total 479 were cast to construct the majority of the arch barrel. The voussoirs are placed in the English or helicoidal arrangement.

The arch barrel is completed by the subsequent injection of non-shrinkage cementitious mortar compound to form the bedding joints.

8.0 Site Supervision Issues

The project supervision was undertaken by Jacobs managed by BEAR. Several difficulties during construction were overcome, primarily due to ground conditions at both the major structures.

Back to Case Study list

A90 Snabs to Star Farm - Cold Lay Asphalt

1.0 Brief Description of the Works

This structural maintenance project is located on the A90 Inverkeithing to Fraserburgh dual carriageway Trunk Road west of Dundee. The works comprised the partial reconstruction and 100mm inlay of the inside lane and 100mm inlay of the outside lane of the eastbound carriageway. Drainage works included replacement of filter material in existing drains and installation of a section of combined kerb/drainage system. A new vehicle restraint system was installed over a section of the nearside verge to offer protection from mature trees.

2.0 Client for the Works

The Client for the works was Transport Scotland (Trunk Roads Network Management)

3.0 Value of Construction Phase

£2.15m

4.0 Name of Contractor

Tayside Contracts Limited

5.0 Commencement of Construction & Duration

Commencement – 3rd November 2008
Duration – 24 Days

6.0 Design Brief

The objective of the scheme was to carry out structural maintenance of the A90 Inverkeithing to Fraserburgh between the Snabs and Star Farm 2 kms. West of Dundee to increase the life of the eastbound carriageway and improve ride quality for drivers.

7.0 Innovation Including Trials and Monitoring

Having successfully tendered for this Contract, Tayside Contracts proposed use of their proprietary cold mix material, Tayset, as an alternative to the specified base layer. This proposal was accepted in consideration of the demonstrated financial and environmental benefits. Tayset is a proprietary material and consequently its production and laying was controlled through Tayside Contracts quality procedures. A Quality Plan for this project was submitted by the Contractor

8.0 Testing

The Contractor carried out rigorous testing to control the manufacture, supply and laying of the material. In particular, the proportions and characteristics of the constituent materials and performance testing of the laid material was monitored to ensure the quality and performance of the product.

9.0 Sustainability

Tayset is a cold recycled bitumen material which consists of a blend of recycled asphalt and virgin aggregate bound with bitumen emulsion. On this project 47% of the aggregate was recycled asphalt planings and the cold mix process resulted in CO2 savings of 43 Tonnes.

10.0 Procurement Considerations

Procurement was through a lane rental measure and value works Contract under ICE 5th Edition Conditions of Contract as required by the client.

11.0 Site Supervision Issues

The construction was supervised by BEAR Scotland. During construction no significant difficulties were encountered and the scheme was completed within the 24 days contract period and £100,000 below the tendered value.

12.0 Traffic Management / Special Requirements

A contraflow system on the adjacent westbound carriageway was utilised to facilitate the works and minimise delay and disruption to road users.

Detailed discussions were held with Perth & Kinross Council, Dundee City Council and Tayside Police in determination of the traffic management.

With no temperature restrictions for the cold mix and lay material it could be produced and stored at the quarry at times to suit efficient quarry operation and its delivery to site was outwith peak traffic flows. Subsequently laying and compacting was easily managed on site.

Back to Case Study list

M8 Newhouse Surfacing Trial

1.0 Brief Description of the Works

This structural maintenance project is located on a section of the M8 Edinburgh to Greenock trunk road between Newhouse Junction 6 (Newhouse) and Junction 5 (Shotts). The works consisted of carriageway reconstruction and inlay for 2.9km. The works included a trial surface course material developed by Transport Scotland and the Transport Research Laboratory with the aim of improving surface course durability.

2.0 Client for the Works

The Client for the works was Transport Scotland (Trunk Roads Network Management)

3.0 Value of Construction Phase

£2.1m

4.0 Name of Contractor

Aggregate Industries UK – Bardon Contracting

5.0 Commencement of Construction & Duration

Commencement - 30th September 2008
Duration - 33 Days

6.0 Design Brief

To carry out structural maintenance on the M8 Edinburgh to Greenock Trunk Road between Junction 6 and 5 over a distance of 2.6km or thereby. The site is in the eastbound direction only

7.0 Innovation Including Trials and Monitoring

As part of this scheme, Transport Research Laboratory (TRL) in consultation with Transport Scotland undertook a trial of modified thin surface courses to assess them for durability and safety. The trial was carried out over a 1.2km section of fully reconstructed carriageway and consisted of a series of 8no 150m long panels each containing a different aggregate size. These were 0/14, 0/10, 0/8 and 0/6mm un-gritted and 0/6, 0/8, 0/10 and 0/14mm gritted in lane 1 only.

8.0 Testing

Initial testing was carried out before opening to traffic and again 3 days after opening using SCRIM, Griptester and Pavement Friction Tester machines. Further monitoring and testing will be undertaken at six, nine and twelve months to examine how the trial surfacing performs under the rigors of heavy traffic. All testing is overseen by TRL.

9.0 Sustainability

It is hoped that the trials will clearly point the way to substantially increase thin surface course durability and confirm the possibility of using local stone which may lead to the redrafting of the specification for Scottish trunk roads and improve sustainability.

10.0 Procurement Considerations

BEAR facilitated a client workshop to discuss the requirements of the trial, the contract requirements and suitability of Contractors. The outcome was that the Tenderers were required to submit a combination of Quality and Fee submission.

11.0 Site Supervision Issues

The construction including the trial panels was supervised by BEAR. During construction no significant difficulties were encountered. Bad weather did delay completion slightly but this was eventually overcome.

12.0 Traffic Management / Special Requirements

A 2 + 2 contraflow was maintained during peak hours in order to minimise delays and disruption to the travelling public. A 2 + 1 contraflow was permitted off peak in order to surface Lane 1.

Detailed consultations were held with Strathclyde Police, Transport Scotland, TRL and Aggregate Industries for the traffic management arrangements which required off peak closures of the eastbound carriageway including the Junction 6 on slip for the testing of the trial with a 2+1 contraflow on the westbound carriageway.


14.0 Any other points of interest

Further testing is ongoing to monitor the performance of the trial panels which is carried out on a Sunday approximately 6 monthly. In order to carry out this further testing a full closure of the eastbound carriageway is required at junction 6 with a 2 + 1 contraflow on the westbound carriageway.

Back to Case Study list

M9 Stirling A9 Overbridge - Resurfacing

1.0 Brief Description of the works

This structural maintenance project is located on the M9 northbound carriageway between the A9 overbridge and the M80 Junction, a length of 2km . The works consisted of carriageway reconstruction of hard shoulder, Lane 1 and Lane 2 to provide a 40-year design life. The works also included the installation of new safety barrier and replacement of road markings.

2.0 Client

Transport Scotland - Trunk Roads Network Management

3.0 Value of Construction Phase

£2.5m

4.0 Name of Contractor

Cemex UK Ltd

5.0 Commencement of Construction & Duration

The works had a maximum construction duration of 42 days. Works commenced on 28th February 2008 and the contractor completed the works 6 days ahead of programme.

6.0 Design Brief

To carry out Structural Maintenance on the M9 Edinburgh to Stirling Trunk Road northbound between the A9 overbridge and the M80 Junction.

7.0 Innovation (products & methods) including trials and monitoring

The works incorporated the use of site obtained recycled type 1 sub-base.
8.0 Testing

Various tests were carried out on all construction layers (bound and unbound) and materials used. These included CBR tests on formation and grading analysis of type 1 sub-base material. Laying records and temperature readings for all bituminous materials placed were compiled by the contractor and submitted to BEAR at the end of each working day. This ensured that the quality of the surfacing could be monitored and kept to a high standard. All tests carried out on or off site were done in accordance with the current relative performance standards.

9.0 Sustainability

On this scheme the bituminous layers and lean mix concrete were planed out in separate layers. All bituminous planings were removed off site to a local store where they were screened and mixed with virgin Type 1 sub-base to create a 50-50 mix. This material was then returned to site and re-used as Type 1 sub base.

10.0 Procurement considerations

Procurement was a lane rental measure and value works contract under ICE 5th Edition Conditions of Contract as required by the client.

11.0 Site Supervision Issues

The construction was supervised by BEAR Scotland. The works were generally carried out on a 24 hours per week, 7 days per week. A member of BEAR’s site supervision team was present at all times on site for the duration of the scheme. Shifts were overlapped to facilitate a handover period to ensure that all supervision members were aware of the current site activities.

12.0 TM / Special requirements

The traffic management consisted of alternate closure of traffic lanes and hard shoulders with a 2+1 contra-flow system in operation; a 40mph mandatory speed limit throughout the works and a 30mph advisory speed limit through the cross-over points were specific requirements of the traffic management.

Back to Case Study list

M9 Torbrex Reconstruction

1.0 Brief Description of the Works

The site is located on the M9 southbound carriageway at Torbrex, near Stirling between junctions 9 and 10. The site is 220m south of the A811 over bridge, and ends 470m north of the Coxithill over bridge, a total distance of 2000m. The works consisted of the full reconstruction of Lane 1 and parts of the hard shoulder and Lane 2. The remainder of the hard shoulder and Lane 2 required a road surfacing inlay. The works also included the installation of a new filter drain, new approach terminals to the safety barrier and replacement of road markings.

2.0 Client for the Works

The Client for the works was Transport Scotland (Trunk Roads Network Management)

3.0 Value of Construction Phase

£1.5m

4.0 Name of Contractor

Tarmac National Contracting

5.0 Commencement of Construction & Duration

The works commenced on the 14/04/09 and lasted for 18 days, finishing on 1/05/09

6.0 Design Brief

BEAR Scotland designed and instructed Structural Maintenance on the M9 Edinburgh to Stirling Trunk Road at Torbrex for 2.0km, or thereby. The site is in the southbound direction only.

7.0 Innovation Including Trials and Monitoring

ANPR camera’s were installed on site in advance of the works contract. These were used to compare the actual delay measured on site with the reports being provided to Traffic Scotland and relayed to the Variable Message Signs across the network as appropriate.

8.0 Testing

Various tests were carried out on all construction layers (bound and unbound) and materials used. These included CBR tests on formation and grading analysis of type 1 sub-base material. Laying records and temperature readings for all bituminous materials placed were compiled by the contractor and submitted to BEAR Scotland at the end of each working day. This ensured that the quality of the surfacing could be monitored and kept to a high standard. All tests carried out on or off site were done in accordance with the current relative performance standards in the Specification for Highway Works.

9.0 Sustainability

On this scheme the bituminous layers and lean mix concrete were planed out in separate layers. All bituminous planings were removed off site to a local store where they were screened and mixed with virgin Type 1 sub-base to create a 50-50 mix. This material was then returned to site and re-used as Type 1 sub base. Sustainable drainage in the form of an over-the-edge filter drain was installed in the verge removing the need for gullies.

10.0 Procurement Considerations

Procurement was a lane rental measure and value works Contract under ICE 5th Edition Conditions of Contract.

11.0 Site Supervision Issues

The construction was supervised by BEAR Scotland. During construction no major difficulties were encountered and the scheme was completed within the 18 day contract period and below the tendered value.

12.0 Traffic Management / Special Requirements

A tidal 2 + 1 contra flow was used which provided 2 lanes northbound in the morning peak, and one lane southbound. This was switched around midday to provide 2 lanes southbound for the evening peak, and 1 lane northbound. This allowed a full closure of the southbound carriageway which decreased the construction period and increased the safety to the operatives and staff on site.

Back to Case Study list

M90 Friarton Bridge Resurfacing

1.0 Brief Description of the Works

Resurfacing of the northbound carriageway during a weekend closure with signposted diversions.

2.0 Client for the Works

The Client for the works was Transport Scotland (Trunk Roads Network Management)

3.0 Value of Construction Phase

£250k

4.0 Name of Contractor

Ennstone Thistle LImited

5.0 Commencement of Construction & Duration

Weekend of 24/25th of August 2008.

6.0 Design Brief

During the Principal Inspection of the structure in early 2008, approximately 90m of the northbound carriageway surfacing was found to be deteriorated along the longitudinal joint with some rutting on the wheel tracks. The surfacing was a SMA laid as a trial approximately 12-14 years ago and has out performed its specifications. It was agreed with the client that the remedial works would be a patching scheme to incorporate the identified 90m as well as any other areas that would benefit with similar patching work. The brief was to replace 45 mm of the wearing course as temporary measure to last 2 to 3 years before the whole deck is resurfaced.

7.0 Innovation Including Trials and Monitoring

The replacement product was also be a polymer modified SMA. This material is deemed more suitable owing to the lively nature of the bridge deck. A HRA was deemed too stiff for this deck.

8.0 Testing

Laying records and temperature readings for all bituminous materials placed were compiled by the contractor and submitted to BEAR at the end of each working day. This ensured that the quality of the surfacing could be monitored and kept to a high standard. All tests carried out on or off site were done in accordance with the current relative performance standards.

9.0 Sustainability

All road planings were removed off site and stored for future use.

10.0 Procurement Considerations

The works were programmed during a period of warmer weather as the Contractor was concerned that wind chill during laying would not produce the desired quality of work. The works were carried out as an ‘As of Right Operation’ under the Trunk Road Term Contract.

11.0 Site Supervision Issues

The variation in bituminous layer depth presented some difficulty for the removal operation.

12.0 Traffic Management / Special Requirements

Works carried out under a night time contraflow with one lane reopened during the day time during the approximately 48hour operation as this is a highly traffic sensitive part of the network.

Back to Case Study list

REPLACEMENT OF LAIRIG EILDE BRIDGE AT GLENCOE

BEAR Scotland worked with the Scottish executive on the £3.7m project to replace the Lairig Eilde Bridge on the A82 at the Glencoe gorge beauty spot which is popular with tourists, climbers and hill climbers. The bridge forms a ‘gateway’ to the North West Highlands.

The decision was taken to replace the stone built crossing, which was constructed circa 1930, due to its condition and insufficient load capacity to comply with current standards.

The new bridge is a three-span reinforced concrete bridge with two circular piers located on the banks of the river. The project will provides two parking laybys and a viewing gallery overlooking the waterfall created where the upland stream Lairig Eilde meets the River Coe.

BEAR has undertaken extensive consultation with numerous interested parties in light of the particular environmental considerations, picturesque location and historical importance of the site, in particular Scottish Natural Heritage National Trust For Scotland and Royal Fine Arts Commission for Scotland.

Work on replacing the 74 year old bridge started in Spring 05 and completed in 2006.

Back to Case Study list

TRUNK ROAD INCIDENT SUPPORT SERVICE

TRUNK ROAD INCIDENT SUPPORT SERVICE KEEPS TRAFFIC MOVING

BEAR Scotland has introduced a Trunk Road Incident Support Service (TRISS) to patrol pre-determined routes across the busiest section of the trunk road network in the South East of Scotland. The aim of the service is to reduce delays and speed up the time it takes to clear the road after incidents.

In the first two months the TRISS teams assisted in excess of 500 incidents on the South East trunk roads since the service came into operation on the 1 April 2007.

Two dedicated, state of the art vehicles, equipped with a variety of tools and materials, patrol the M8, M9, A720 and the A1 between 0600 till 1830 seven days a week.

The TRISS operation incorporates the innovative use of roof mounted solar operated mobile variable message sign. These provide immediate, on-the-spot information and early warning signs at the scene of an incident whether it is an accident or, more likely, a breakdown. These signs have been adapted following the success of a similar service provided by BEAR Scotland on the A92 Dundee – Arbroath since early 2006.

The teams are often the first at the scene of road traffic accidents, where they can assist the police with traffic management and offer emergency first aid if needed. The service also allows police officers to make better use of their time.

The TRISS teams all undergo a rigorous selection and induction process. They all must have experience and training in traffic management skills, possess excellent driving skills, sound judgements under pressure, good communication skills and an emergency first aid qualification as a minimum.

Bill Taylor, BEAR Scotland’s Managing Director says: “The roll out of the service has been extremely successful in helping to keep traffic flowing in this part of the network.

“In the first two weeks of operation the teams attended over 200 incidents. The service will benefit drivers by helping to keep roads safer, clearing incidents much more quickly and cutting down on congestion“.

BEAR, provides this service as part of the contract to manage and maintain the Trunk Road Network in the South East of Scotland on behalf of Transport Scotland.

A Transport Scotland Spokesperson adds: “The introduction of TRISS on our south east network will bring significant benefits due to congestion associated with broken down vehicles being removed. The dedicated TRISS service responds quickly and has been well received by the police and public.”

Back to Case Study list