Blackpool Tramway Extension

This project refers to the construction for the Blackpool tram extension, from the existing track at the North Pier up Talbot St to Blackpool North Station, began in June of 2018 and was completed in accordance with the original construction program to meet the Talbot Rd opening date of 28^th of February 2019. The newly installed system tied into the existing live track at the North Pier. Steconfer were responsible for all construction related to the embedded track works from the C8/10 blinding layer to the finished road/rail level. Additionally, Steconfer were responsible for all overhead line equipment works and the design and installation of the signalling system.

The works scope

The Blackpool tram extension main infrastructure works contract was a sesign & build initiative and included all design, construction, testing & commissioning and bringing into service of the new tramway, including all ancillary and temporary works. Due to the failure of the client to relocate the Wilko store it was not possible to fully complete and commission the track and systems at this phase. A remobilisation date of April 2021 has been set to complete all works in the vicinity of the North Terminus and begin the commissioning process. There were smaller contracts in place for advance resolution of some of the Utilities, and a Power & Systems contract. Steconfer as the nominated subcontractor for embedded track slab, OLE and Signal systems were responsible for approximately 50% of the total value of the works.

Steconfer works included:

• Confirmation of formation level
• Track works including embedded, slab and ballast
• 2 tram stop/platform installations
• Cable ducting & road, track & stop drainage
• Tie-in of tracks and OLE system to existing lines at North Pier
• Installation of all cast-in elements for signalling works
• Installation of all wayside equipment for signalling and communications
• 1 double track junction consisting of 2 turnouts and a diamond crossing

Designing for successful track delivery & systems integration

• Responsible for signalling systems design and integration with all other disciplines
• Procurement and installation of all OLE poles
• Procurement of OLE small part steelwork and assemblies
• Coordination with others for the completion of the highway
• Liaising with a nominated subcontractor for public lighting
• 1 double crossover (Bretelle) procured to be installed when the council relocate Wilko’s store
  
  Delivery of quality and safety managed efficient construction started at the design stage. Capturing all of the actual requirements of the scheme, challenging them and resolving them one at a time was one of the important elements of the successful construction of the scheme. Solving problems on paper and gaining consensus and approval before commencement allowed considered procurement, confidence in the program, reduced disruption through efficient construction, and informed stakeholders. Collaboration at these early coordination stages facilitated collaboration during the delivery phases.

The track system between the North Pier and North Terminus comprises approximately 550 m of embedded double-track interrupted at intervals by stops/platforms. The slab was set at a depth of 500 mm from the finished rail level with allowance for a 150 mm C8/10 blinding layer as a working platform. The choice to use structural concrete for blinding was to allow construction traffic after an appropriate curing time and to provide sufficient strength for all props to be anchored. As with the majority of light rail systems, the rail was encapsulated to counteract the effects of stray current, present from the DC voltage used to power the tram. The encapsulation chosen for this project was Pandrol CDM. The use of CDM means their proprietary QT Track system for track alignment had to be used. The QT jigs allow for a top-down method of construction whereby the rails are suspended at their finished alignment and structural C40/50 concrete is poured to a finished level 120 mm below the finished rail level. Our specialised track surveyor ensures the alignment is within the construction tolerances to design and submitted a pre-pour report to the client before all pours. Additionally, the track surveyor was present during the pouring process to ensure no negative effects on the alignment caused by weather conditions or from the concreting process. This initial pour was referred to as the track slab pour and was sufficient to embed the rails and allow the jigs to be removed.

The remaining 120 mm was finished with either asphalt or pigmented concrete depending on the designated operation of the highway in any given area. If the area allowed vehicular traffic in addition to the tram the finish was asphalt with concrete shoulders on either side of the rail and encapsulation of a width of 225 mm. When the area was segregated from traffic the finish consisted of pigmented C40/50 concrete with an exposed aggregate finish. It was decided to add filaments to the finishing concrete to protect against freeze-thaw action and chipping. This is particularly important in shared areas where the road/rail interface at the shoulder is a constant source of the problem.

Following the completion of the second stage pour the track surveyor completed a post pour alignment including the relative overlap with the adjoining section. The Amberg GRP100 track trolley was used to conduct a uniform survey of the entire track at the end of this phase of the project.

OLE construction

Steconfer were responsible for the installation of all OLE poles, assemblies and contact wire. Involvement began early at the design progression phase. Due to architectural requirements and third-party interfaces (illuminations, public lighting, etc.), considerable attention had to be paid to all aspects of the pole manufacturing in addition to ensuring the loading requirements. Steconfer were responsible for integrating all requirements from all stakeholders to procure poles that satisfied all parties. In total, in this initial phase of the project, 49 OLE poles were installed which included phasing works to enable track slab construction at the tie-ins.

An enabling design was required to remove existing OLE poles and bases which fell within the DKE of the new track alignment. It was necessary to install 5 new OLE poles and associated assemblies to register the contact wire and allow the removal of 5 existing poles. The works were completed over a 5-night duration (power off) and successfully handed over to the operator following a thorough inspection and height and stagger survey. A detailed as-built was supplied to the operator and the client on the successful completion of the works.
Steconfer had considerable involvement in defining the earthing and bonding requirements in conjunction with Arup as they related to OLE design. This included a risk defined Overhead Clearance Fall Zone (OCFZ) which controls the requirements for Voltage Limiting Devices (VLDs). All poles required earthing by means of rods whether or not they fell within the OCFZ. Sufficient earthing was achieved through testing to ensure the resistance of approximately 10 Ohms.

Another challenge encountered in the OLE design was ensuring that the system and components procured allowed for a dual tram interface as the heritage trams are still in use on the Blackpool tramway. This meant that all components such as crossings or frogs must safely allow the passage of both pantographs and trolley poles. All components had to be marine graded treated given the high exposure and chloride levels in the seaside environment.

Signalling system design and installation

Steconfer, in conjunction with our specialist signal designer, were responsible for the design, procurement, integration, and installation of the signalling system at the Blackpool tram extension project. The signalling system was comprised of a combination of line-of-sight signalling, tram detection and integration with traffic signalling and junctions. The placement of detection, cast within the track slab, was critical to ensure the safe future working of all LRT and traffic signals. Care had to be taken that all ducts etc. were placed to integrate into the pavement and highways design. Additionally, placement of the detection (transponders) had to integrate with the future planned road markings which controlled the placement of traffic signals. These needed to be placed correctly to avoid considerable re-works towards the end of the project.

The signalling system was required to integrate with the existing system in operation on the mainline and this required condition assessments of all previously installed equipment. Given that some components such as point machines were installed up to 5 years previously this involved a significant amount of reconditioning to ensure their function and integration. 3 signalling cabinets were supplied and installed at the 3 junctions, positioned to ensure a sensible interface with the traffic control cabinets. The cabinets were configured internally to match the system requirements and outputs to the traffic cabinets.

The placement and number of ducts were carefully controlled to comply with the work’s information with a provision for one future route should it be necessary.