Evolution of the bus maintenance garage

Whilst much attention has been placed on the transition of the UK’s PSV fleets from diesel to hybrid and electric powertrains, bus garages and workshops have also evolved considerably to accommodate these changes.  Transformation to BEV propulsion has required operators to make major investments in upgrading maintenance depots, alongside skills development for technicians.

Examples include Arriva’s electrification of its Thornton Heath depot in south London which is set to run 109 zero-emission buses from Spring this year.  The facility is the third to benefit from the operator’s £730m modernisation programme, which will see all 14 of its depots in the capital electrified by 2030, in accordance with Transport for London’s decarbonisation strategy.  Alongside the removal of diesel refuelling tanks, the upgrade at Thornton Heath required installation of a new electricity substation and five kilometres of cable to meet the increased power needed to recharge multiple electric buses simultaneously.

Operators outside the capital are equally active, investing in the depot infrastructure needed to support zero-emission buses.  Stagecoach’s Sunderland depot, for example, now has ten twin charging points for its 20 Yutong single-decker electric buses, which operate routes across the North East.

The history of the bus garage stems back to the coaching inns of the 17th to 19th centuries when horse-drawn carriages were the main form of transport between towns and cities.  Travelling for short ‘stages’ of 10-15 miles, it was necessary for stagecoaches to stop frequently at coaching inns where horses would be changed and passengers could eat and rest.  Despite developments with steam and electric-powered ‘omnibuses’, horses remained the principal form of power into the early 1900s, with organisations such as the London General Omnibus Company (LGOC) harnessing 7,000 horses to haul its fleet of omnibuses, according to the London Transport Museum’s records from 1905.

New bus garages with repair facilities appeared around the same time, supporting the advent of mass produced petrol-powered buses, such as the LGOC’s B-Type, which was introduced in 1911, to serve routes throughout the metropolis.  Within a decade, LGOC had built 3,000 B-Type chassis at its Walthamstow factory and even electric buses began at this time with the introduction of the trolleybus.  Developed by the Siemens brothers and powered via overhead wires and trolley poles, Bradford and Leeds became the first cities in the UK to introduce trolleybus services in 1911.

Bus garages have evolved alongside the development of bus powertrain technology and the expansion of manufacturers and models ever since, providing routine inspections, maintenance and repairs.  Vehicle such as the iconic Associated Equipment Company (AEC) Routemaster, which entered service in 1956, ushered in new technologies such as power steering, hydraulic braking, fully automatic transmission and independent front suspension.  These systems required bus garages to be suitably equipped and mechanics with the appropriate skills to maintain them.

Today’s PSV maintenance depots are sophisticated facilities that employ maintenance management systems to automate tasks and improve efficiency.  Engineering practices have developed in line with vehicle technology, such as the introduction of electronic engine and transmission controls in the 1980s and Euro VI emissions systems in the past decade, through to today’s use of onboard telematics and AI-based software to provide live vehicle data, manage onboard batteries and predict vehicle issues before they result in breakdowns.  Operators utilise a range of sophisticated diagnostic tools to support their technicians in diagnosing and repairing faults on these advanced systems.

Developments in bus drivetrain technology, initially with the introduction of diesel-electric hybrids and now battery electric, have required a step change in maintenance practices in areas such as air compressors, used to provide the energy source for braking and door systems.  Previously engine-driven, hybrid and electric buses are equipped with standalone electrically powered e-compressors to provide the air supply.  Typically mounted under the chassis, e-compressors require regular oil and filter changes in line with manufacturer guidance and each vehicle’s duty cycle to maximise service life.

As one of the UK’s leading OEM parts distributors serving PSV operators throughout the country, Imperial Engineering has also continued to evolve in line with advancements in bus technology and maintenance.

Today, the business is managed by the fifth generation of the Dwight family who continue to carry forward the company’s principles for professionalism, service, expertise and integrity.  Imperial Engineering is proud to be recognised as a leading supplier of OE bus and components, including parts for the latest electric models and is pleased to support operators with technical advice and guidance.