Preparing for electrification
In order to deliver the MML upgrade, a significant construction programme is required. To prepare for electrification we may need to make the following changes:
- upgrade bridges and tunnels
- carry out enhancement works to bridge parapets
- strengthen railway embankments
- assess footpaths/level crossings
- clear overgrown vegetation
- undertake piling work to install the foundations for structures that will carry overhead lines
- install overhead line equipment.
Midland Mainline map
As we enhance our infrastructure we also work to minimise our impact on the natural environment. Before any work begins we carry out ecological surveys and environmental impact assessments where required to identify any protected species or nesting birds and relocate them where necessary.
Alongside our partners we try to make sure our sites are managed responsibly and to minimise the impact of works on people living close to the railway. We minimise noise and brief teams on working responsibly in the local community.
Keeping you informed
Under our licence conditions we have to work at times that cause the least disruption to train services. This means carrying out a lot of our improvements during the night, at weekends and bank holidays.
Work to structures such as bridges can require road closures and diversions. We understand this can cause inconvenience, however the safety of road users, pedestrians and our personnel remains paramount.
Before electrification, we will address lineside vegetation along the route. This is to prevent interference with overhead line equipment and reduce the risk of short circuits to parts of the electrified system. Mature vegetation will usually be cleared to a distance of six metres from the railway – while a proportion of vegetation will be preserved for its ecological benefits.
Unmanaged, overgrown trees and plants can cause serious safety problems as well as train performance issues, such as:
- covering up signals or falling onto tracks and overhead power lines
- stopping our workers finding a safe refuge when trains are passing, and hampering their ability to see trains approaching
- reduced visibility at level and footpath crossings
- autumn leaves falling onto tracks – when railway traffic crushes them at 20 tonnes per square inch they form a hard, Teflon-like coating that reduces trains' ability to grip and affects acceleration/braking, leading to delays.
Overhead line equipment
The MML will be electrified using a 25kV overhead line equipment (OLE) design. This refers to the wires and supporting posts that distribute electricity at 25,000 volts to power trains.
Generally, most types of railway overhead line equipment have overhead conductors with a copper contact wire suspended from a catenary wire by 'droppers' or 'drop wires.'
These conductors are suspended from trackside steel masts mounted upon concrete foundations spaced around 40m to 70m along the track (depending upon local terrain). The 'live' parts of the equipment are insulated from the structures by porcelain or polymeric insulators.
Electricity to power the MML will be drawn from the National Grid high voltage transmission network via four grid access points and distributed along its length through 24 substations. We will aim to place new equipment where it will cause the least visual impact. However, this infrastructure will change the appearance of the railway and surrounding area.