In an era marked by the urgent need for sustainable solutions to combat climate change, the rail industry is undergoing a transformative shift. Decarbonization, defined as the reduction of carbon emissions, is central to this transformation.
Network Rail, a key stakeholder in the UK’s transportation infrastructure, has been at the forefront of implementing a comprehensive decarbonization strategy. This strategy is multi-faceted, encompassing electrification, the use of alternative fuels, and the implementation of energy-efficient technologies.
A key pillar of this strategy involves Overline Structure Clearances and Stations Wire Height Risk Assessments. These assessments provide the technical foundation for electrification projects, offering critical data on the feasibility and requirements for converting existing diesel-powered lines to electric or hybrid systems.
The Feasibility Assessment Report done by Andromeda Engineering with specialist subcontractors SDEA_Engineering Solutions and DGauge, provides a granular look at the electrification potential of various routes and bridges. The technical scope is broken down into three main route sections, each with its unique set of challenges and opportunities:
- Didcot to Oxford (Route Section 4)
- Electrification feasibility assessments include load calculations, clearance evaluations, and structural integrity checks at key points like Appleford Station and Appleford Road Bridge.
- Culham Station presents unique challenges due to its footbridge and adjacent road bridges, requiring specialized structural assessments.
- Chippenham to Bristol Temple Meads including Bath Corridor (Route Section 7X 7K)
- This section involves a series of bridges, each with its own set of electrical and geometric clearance challenges. Advanced simulation tools were used to model different electrification scenarios.
- Bristol Parkway to Bristol Temple Meads (Route Section 6F)
- This route section involves multiple bridges, each requiring a unique set of engineering solutions. Structural integrity assessments and load-bearing calculations are critical here.
The approach adopted in the assessment follows the guidelines set forth in the Electrification & Plant Technical Advice Note: Electrical and mechanical clearances on overhead electrified railways 12-21-002-V1a. Hence, Voltage-Controlled Clearances solutions were evaluated to facilitate efficient electrification while avoiding bridge reconstructions or track lowering, all within safety parameters.
Figure 1. Sections showing registration supports for a feasible solution with a VCC approach.
The VCC is a methodology of determining electrical clearances using impulse voltages. The impulse voltages can be reduced with the use of mitigations which can be used alone or in combination. Some of the mitigations are surge arrestors and supplementary insulation as contact wire cover or insulating coating applied to overbridges.
The feasibility assessment has taken into consideration:
- mechanical clearances between all equipment,
- electrical clearances between live and earthed equipment,
- clearances between pantograph profiles and structures using probabilistic techniques,
- pantograph geometries, head rolls, sway and carbon wear,
- high accurate surveys,
- track fixity (vertical, horizontal, cross level),
- track cant,
- track vertical and horizontal curvatures,
- cant deficiency,
- reduced installation tolerances for track and electrification equipment,
- contact wire uplift, wear and stagger,
- wind speeds and
- kinematic gauge profiles.
Bath Road Bridge near Bristol Temple Meads station serves as a case study in efficient engineering solutions for electrification. The bridge’s structural design is a steel tied arch type, involving a main girder and secondary girders arranged in a fishbone pattern supporting four road lanes, a cycle lane and footpaths.
Advanced survey techniques, such as SGT LaserFleX2 and RILA-3, were employed to ensure accurate measurements. These techniques allowed for precise clearance evaluations, which are critical for determining the feasibility of electrification.
The report concludes that a Voltage-Controlled Clearances (VCC) solution is viable for all tracks, thereby eliminating the need for track lowering or bridge reconstruction. This finding is significant as it paves the way for cost-effective electrification at Bristol Temple Meads, one of the busiest stations outside of London.
The Feasibility Assessment Report’s findings are groundbreaking for several reasons:
- The majority of the assessed bridges do not require significant structural interventions, which is a boon for project timelines and budgets.
- The use of advanced survey and simulation techniques has proven to be invaluable in assessing the feasibility and requirements of electrification projects.
- Collaboration between multiple stakeholders, each bringing a unique set of skills and expertise, is key to the success of complex decarbonization projects.
Decarbonization is not merely an environmental goal; it’s a complex technical challenge that demands innovative engineering solutions. The collaborative efforts of Andromeda with subcontractors SDEA_Engineering Solutions and DGauge are setting new benchmarks in sustainable rail infrastructure. Their work serves as a model for how technical ingenuity and collaborative problem-solving can contribute to the broader goals of decarbonization and sustainable development.