Editing Maintenance of way (section)

== Electrification systems ==
[[File:Electrification work at Cardiff Central.png|thumb|300px|Maintenance of overhead line equipment at Cardiff Central, in Wales]]
{{Further|Railway electrification}}
{{expand section|date=December 2023}}
On rail lines which include electrification by a [[third rail]] or an [[overhead line]] system, maintenance of way work also includes installing, repairing and replacing these systems.{{Sfn|Keenor|2021}}{{Sfn|Semmens|1991|pp=93-112}}{{Sfn|Rosbotham|Hall|1960}}

Overhead line electrification while complex, is a task that with proper planning, done from trains on existing rail lines. British Rail, during the 1960s-1980s, during large scale projects to electrify routes such as the [[West Coast Main Line]] and [[East Coast Main Line]], developed trains that could carry out the various tasks, boring foundations for supports, preparing cement, standing up steel support structures and attaching the contact wire, in an assembly line like fashion.{{Sfn|Rosbotham|Hall|1960}}

The electrification of an existing route, can involve significant additional work to accommodate the new electrical system, such as changes to or complete demolition and rebuilding of bridges, station canopies and tunnels. Alternatives to enlarging a tunnel, or rebuilding a bridge, can include lowering the track bed, in turn lowering the tracks.{{Sfn|Semmens|1991|pp=113-147}}{{Sfn|Keenor|2021|pp=293}}

Contact wires have a lifespan of around 20-30 years. Beyond this point, the likelihood of a wire breaking, and falling from the overhead support structure, as well excessive wear on other components that connect the contact wire to the overhead structure.{{Sfn|Keenor|2021|pp=311}} Failure to keep up with this maintenance can lead to catastrophic damage to both the overhead wire system as well as on train equipment, particularly the [[Pantograph (transport)|pantograph]], even at relatively low speeds.{{Sfn|Keenor|2021|pp=2}}

Trees and other vegetation pose a hazard to overhead wires: falling tree branches can cause wires to disconnect from the support structure and [[Arc flash|arcing]] can occur if vegetation gets too close to wires.{{Sfn|Keenor|2021|pp=293}} This poses significant hazards, from bright light of an [[arc flash]] and starting fires, as well as disruptions to railroad operations from tripped [[circuit breaker]]s and downed wires.{{Sfn|Keenor|2021|pp=34}} The development and consistent following of plans to control vegetation near overhead lines is critical to safe and uninterrupted rail journeys.{{Sfn|Keenor|2021|pp=293}} This typically involves the trimming of branches that have strayed within a predetermined distance of the wires, as well as removal of trees that are simply too close to overhead wires and will always pose an issue.{{Sfn|Keenor|2021|pp=293}}