Class 175

Earlier this month there was a report that Great Western Railways services were being cut due to issues with Class 175 trains.  [BBC News]

A number of rail journeys will be cancelled across Devon and Cornwall from next week due to recurring issues with a fleet of trains, a rail operator has said.

Great Western Railway (GWR) said five weekday services will be cancelled between Penzance and Plymouth/Exeter from Monday.

The issue is down to the company's Class 175 fleet, which it said had been "challenging from a reliability perspective," prompting too many cancellations for customers.

The operator said it understood the timetable changes would be "frustrating for customers" but believed the move would "provide a more reliable service in the short term" while it worked to bring its fleet up to standard. 

I must admit I know very little about trains in the region but I have been looking into the class 175...

The 25-Year Journey of the Class 175: From Birmingham to the South West

1. Introduction: The Coradia Philosophy

The British Rail Class 175 represents a vital chapter in Alstom’s Coradia family, a global lineage of passenger trains defined by a commitment to smart, sustainable mobility. As a market leader in rail services, Alstom designed the Coradia platform to be adaptable; in the United Kingdom, this vision manifested in the versatile Class 175 regional units and their high-speed sibling, the Class 180. While the 180 was built for express speeds of 125 mph, the Class 175 was engineered as a 100 mph workhorse, bridging the gap between local stopping services and long-distance regional travel.

The journey of the Class 175 spans over a quarter-century, beginning with its initial order in 1997 and continuing through its current rejuvenation under Great Western Railway (GWR). This narrative traces how a fleet of 27 trains evolved from a regional solution for the North West into a digitally advanced asset serving the rugged coastlines of the South West.

While the "Coradia" philosophy provided the intellectual blueprint for these trains, their physical story began amidst the industrial heritage of the English Midlands.

2. Origins and Architecture: The Washwood Heath Era (1997–2001)

The Class 175 was born from a 1997 order placed by North West Trains, a £78 million investment aimed at a total overhaul of regional rail standards. The transition from locomotive-hauled coaches to Diesel Multiple Units (DMUs) represented a significant shift in railway philosophy: DMUs offered superior operational flexibility, faster turnaround times, and reduced track wear compared to heavy locomotives. The primary goals of this order were:

• Replacing the "Heritage" Fleet: To phase out aging Class 101 units that had served since the mid-20th century.
• Retiring Locomotive-Hauled Trains: To modernize long-distance corridors to Bangor and Holyhead by replacing heavy engines and coaches with efficient, self-propelled sets.
• Modernizing Regional Service: To provide a standardized, contemporary passenger experience across the North West and West Midlands.

The fleet was constructed at Alstom's Washwood Heath facility in Birmingham. To support the units, a purpose-built maintenance depot was established at Chester, replacing the site’s former locomotive sheds. A notable milestone in their development was the use of the Severn Valley Railway for low-speed testing, where the units were first put through their paces on heritage tracks before commencing high-speed trials and driver training on the national network.

Technical Specifications

The fleet was divided into two distinct configurations to balance capacity and operational needs:

Unit Class	Car Formation	Technical Stats	Capacity
Class 175/0	2-car (DMSL-DMSL)	Weight: 99.5 tonnes  Length: 23.713m (per car) Width: 2.73m Max Speed: 100 mph	134 seats
Class 175/1	3-car (DMSL-MSL-DMSL)	Weight: 146.761 tonnes (set) Length: 70.45m (total set) Width: 2.73m Max Speed: 100 mph	206 seats

With their construction complete and rigorous testing at the Severn Valley and beyond concluded, the Class 175s were ready for the challenges of the modern rail network.

3. The Operator Carousel: Regional Migrations

Throughout its life, the Class 175 has been a "migratory" fleet. While owned by Angel Trains, the units have moved between various Train Operating Companies (TOCs) due to franchise re-organizations and the introduction of newer fleets, such as the Class 185 "Pennines." This adaptability has allowed the units to remain productive assets even as regional requirements shifted.

Operator Timeline

Era	Operator	Primary Routes/Regions
2000–2003	First North Western	North West England, West Midlands, North Wales Coast
2003–2004	Wales & Borders	Transfer of North Wales Coast services
2004–2024	Arriva Trains Wales / TfW	Wales-wide services, Manchester, Holyhead
2004–2006	TransPennine Express (Sub-lease)	Long-distance North West routes
2024–Present	Great Western Railway (GWR)	South West England (Devon & Cornwall)

While the branding on the exterior changed frequently, the internal technology was quietly undergoing a digital revolution to ensure the fleet’s survival.

4. Technical Hurdles and Digital Evolution

The early years of the Class 175 were hindered by "teething troubles," specifically involving the reliability of brakes and bogies. However, Alstom’s commitment to the fleet through extensive remedial work resulted in "greatly improved" reliability, transforming them from struggling newcomers into dependable regional staples.

Beyond mechanical fixes, the fleet embraced a digital awakening. In 2007, the Passenger Information System (PIS) was reprogrammed to include Welsh language support and an audio chime to alert passengers to announcements. The most profound shift, however, came with the introduction of condition-based monitoring.

The Digital Transformation: HealthHub The Class 175 now utilizes Alstom’s HealthHub solution, a predictive maintenance platform that turns the train into a "smart" asset. The system captures over 200 parameters every 30 seconds—including speed, carriage temperature, and GPS coordinates.

Three Key Benefits of Predictive Maintenance:

1. Real-Time Monitoring: Constant health surveillance of the train while in active service.
2. Incident Prevention: Detecting failing components before they cause a service-ending breakdown.
3. Predictive Alerts: Automated notifications allow maintenance teams at the Laira depot to have parts ready before the train arrives.

This transition from mechanical struggle to digital sophistication paved the way for the fleet's new mission in a completely different corner of the UK.

5. The GWR Rejuvenation: A New Chapter in the South West

In 2024, a landmark £75 million contract between Alstom, GWR, and Angel Trains secured an eight-year future for 26 units of the fleet. This agreement is a significant boon for the local economy, supporting over 15 specialized roles—including engineers, material planners, and administrators—while providing a "tangible boost" to the wider rail supply chain.

The reintroduction of these trains allows GWR to retire older, less efficient diesel units. This provides passengers with improved comfort and punctuality while serving as a bridge toward the eventual decarbonization of the regional network.

Key Routes in Devon and Cornwall:

• Exeter St Davids
• Penzance
• Barnstaple
• Okehampton

As these trains settle into their new home in Plymouth, they carry a legacy of resilience into their second quarter-century of service.

6. Summary: The Legacy of the Class 175

The 25-year history of the Class 175 offers three critical takeaways for the student of railway history:

1. Adaptability: The fleet has survived and thrived through multiple franchise shifts, proving its versatility across diverse geographies—from the flat North West to the steep gradients of the South West.
2. Modernization: It represents the industry shift from reactive "fix-it-when-it-breaks" maintenance to proactive, digital predictive maintenance via the HealthHub system.
3. Regional Impact: From replacing heritage Class 101s in 2000 to modernizing branch lines in Cornwall today, the Class 175 remains a vital tool for connecting diverse UK communities.

Now under the expert maintenance of Alstom’s Laira depot, the Class 175 remains a relevant and essential component of Britain’s journey toward a smarter rail future.

So nice trains but clearly there are still issues. More this week...