Glasgow’s Subway is the world’s third-oldest underground railway (after London and Budapest). When it opened in 1896, there was no rail connection to the surface so cars were lowered into the tunnels from the depot above.

Although trains were steam-powered, there was no smoke in the tunnels. Instead, a stationary steam engine moved a 10.5 km long continuous cable in the track bed at a constant 19 km/h. Trains were moved by a gripper that closed around the moving cable, as on San Francisco’s cable cars today.

Since it opened, there have been two modernisation programmes. In the late 1930s the original cars were converted to electric traction. Between 1977 and 1980, the Subway was closed for a major enhancement programme that included the reconstruction of some stations, tunnel repairs, track bed and rail replacement.

This provided the Subway with its first points as part of a triangular junction to provide a surface rail connection to the Govan depot. The 80-year old wooden cars were replaced with a fleet of 33 new coaches. A further eight trailer cars were added in 1992 so that all trains could be three-car units. As 12 trains are required for normal service, the additional carriages allow for a planned maintenance regime.

The third modernisation

The 1970s Subway refurbishment has served Glasgow well, with 13 million passenger journeys undertaken each year. However, after nearly 40 years, it was time for another major enhancement programme. As SPT senior director Charlie Hoskins told Rail Engineer, significant investment would be needed to attract more custom and reduce rising operation and maintenance costs. Otherwise closure would become almost certain.

So, in 2011, Strathclyde Partnership for Transport (SPT) initiated a £288 million modernisation programme with the Scottish Government contributing £246 million. Charlie detailed the five main strands to this programme, smart ticketing, station refurbishment, infrastructure asset renewal, rolling stock and control system replacement, as well as organisational change.

Getting the workforce’s commitment to new working practices was an essential first step of the modernisation programme. SPT achieved this in 2012 with an agreement between UNITE and SPT for more flexible working and establishment reduction with no compulsory redundancies.

Contactless Subway smartcards were introduced in 2013. Developed by Nevis Technologies, a joint venture between SPT and Ecebs, these cards comply with the UK ITSO standard and so can be used on other public transport. This is likely to happen soon, as Transport Scotland is actively promoting smart ticketing and Nevis was appointed by Abellio ScotRail in 2015 to provide smart ticketing for their franchise. Nevis is also to provide smart-card systems to McGills, Scotland’s largest privately owned bus company.

Subway travellers have now been issued with over 110,000 smartcards. In 2015, Smartcard top up was extended to 45 retail outlets close to Subway stations using the Payzone system that also accepts payments for utility and credit card bills.

Station refurbishment

Refurbishing the Subway’s fifteen stations accounts for around £50 million. This started in July 2011 with the second busiest station, Hillhead, which was completed fifteen months later. To avoid passenger disruption, 90% of the work had to be done in short night-time possessions.

Hillhead set the benchmark for other station refurbishments. It is now an attractive, bright, modern station with new SPT branding. Such revitalised stations attract new patronage and also reduce operating costs by using lower whole-life-cost modern materials and energy efficient lighting. Almost all the system’s 28 escalators have been replaced by power-standby, energy-efficient versions. The remaining two at Kelvinbridge station will be replaced later this year.

The new stations incorporate DDA enhancements including hearing loops, tactile maps and paving, and colour contrast flooring. However, with the constrained nature of the Subway’s small stations, it has only been possible to fit lifts at Govan and St Enoch, where work was completed in 2015. Work at Govan station, and its bus interchange, will be complete in August 2016.

By the end of August, seven stations will be complete and work is due to commence at Cessnock and Kelvinbridge. The remaining six stations are currently progressing through the design stages. There are three framework contractors for this work (Graham Construction, Sir Robert McAlpine and Clancy Docwra) and two framework designers: Austin Smith Lord and AHR.


Leaking tunnels

The modernisation programme includes a comprehensive programme of infrastructure works including tunnel repairs. The Subway’s two circular tunnels are 10.5 km long with a nominal diameter of 3.35 metres and are between three and forty metres below ground level. They pass under the river Clyde twice and are mainly within the groundwater table. Construction methods varied according to the differing geology so there are brick circular, brick horseshoe, concrete and cast iron linings.

Historic records show that the ground conditions encountered were hard going (rock) or particularly poor (loose sands/muds). The worst section between Buchanan Street and Kelvinbridge also passed through former quarries. The differing forms of construction, in conjunction with changes in the surrounding soils, have led to varying degrees of deterioration over the last 120 years, resulting in an overall increase in water ingress with resultant maintenance problems, including rail corrosion.

On a positive note, SPT has found a way to exploit this waste water, which has a temperature between 14 and 15°C. In partnership with Glasgow Caledonian University, heat-pump systems have been installed at two stations to demonstrate their feasibility as a sustainable heat source. This has also led to the installation of air heat pumps as the air temperature is also relatively constant and can be utilised in a similar way to the water heat source. This initiative won the 2016 Scottish Transport Award for contribution to sustainable transport.

In 2014, Freyssinet won a £17 million contract to upgrade the tunnel lining. In the worst four-kilometre section, this work includes annulus grouting, lining repairs and resin injection leak-sealing. This is done during night- time closures over a two-year period with an average labour force of eighty. The 21 pumping stations are also having their pumps replaced as part of a £2 million contract awarded to WGM Engineering in 2014.

Other tunnel work included the removal of 120 kilometres of redundant cable and the provision of a new chainage system to re-baseline tunnel survey datum. New datum plates with radio frequency identification are being installed. Malcolm Hughes Land Surveyors were awarded a half million-pound contract for this work in 2014.

The only closure

2014 also saw the award of a £1.1 million contract for the supply of rail to Austrian-based Voestalpine Schienen GmbH. This supports an accelerated re-railing programme which is to be completed by 2017. This is needed because of the condition of existing rails and the requirement to start testing the new rolling stock at night.

Other permanent-way work is the £5 million design and build contract, let in 2015 to Colas Rail, to replace the track system within the depot access ramps and turnout chambers that were installed during the 1979 modernisation. This includes replacement of the concrete track bed and drainage and renewal of the plain line rail, switches and crossings, and point motors.

Although the intention is to modernise the Subway without disruption, closure cannot be avoided for this work. Hence, the system was closed during the month of July. During this time replacement bus services were provided, mimicking the circular service on the surface streets above.

Made-to-measure trains

Impressive though the station and infrastructure works are, the new trains will no doubt attract the greatest attention as they will be the first trains to operate in the UK with UTO (unattended train operation).

Charlie Hoskins explained that SPT did not procure its trains on the basis of a prescriptive technical specification as this might rule out a worthwhile technology. Instead, prospective suppliers were given a concept of operation that covered general requirements such as the number of people to be carried and how SPT wished to operate the trains. A competitive dialogue then followed to develop the technical solution that offered best value. This approach was supported by Glasgow-based consultant Racon and by Systra which, with SPT key staff, formed the client’s technical, commercial and procurement team.

In March, SPT announced that their new trains, signalling and associated equipment will be supplied by a consortium of Stadler Bussnang AG and Ansaldo STS.

No caption required - essential

Although there had been concerns that suppliers may not be interested in an order for a small number of four-foot gauge Subway trains, this proved not to be the case. Charlie commented that the Swiss company Stadler was “quite excited at the idea” as it has a bespoke manufacturing operation and its production lines can easily be changed to produce small orders, such as 34 cars for the Berlin Underground and 10 Croydon trams.

Stadler is to supply 17 four-car articulated trains with wide walk-through connections and a standard floor height, made possible by using smaller diameter wheels. Each train will be 39.25 metres long, compared with 37.74 metres for the current three-car units. The trains have 58 km/hr maximum speed and will have capacity for 310 passengers compared with the current 270. They will also accommodate wheelchairs.

Charlie pointed out that SPT did not specify 17 trains, this was the number of trains that the consortium felt were needed to move the required number of people over a period of time with an allowance for maintenance.

Predictive maintenance

Senior project manager Willie Delaney stressed that new trains’ design focuses on reduced maintenance and operational costs with improved reliability from predictive rather than scheduled maintenance.

They will have secondary air suspension and cushioned, resilient wheels. This both improves ride quality and allows tyres to be replaced without the use of a heavy hydraulic press. The wheelsets will have radial steering to reduce flange wear. The depot will have wheel condition monitoring equipment, taking daily wheel profile measurements to predict when tyre turning is required.

The AC traction motors will be water cooled with IGBT traction control that offers regenerative braking. Systems will be continuously monitored to detect potential defects. For example, increased effort and time to close a particular door indicates an emerging problem, allowing the problem to be investigated before the door fails. A system failure sends an alarm to control, complete with advice on the required action. With high levels of redundancy, it is unlikely that a fault would require a train to be taken out of service immediately.


UTO requires a fully automatic signalling and control system. A key requirement is for controllers to monitor trains with on-board CCTV and to communicate with passengers if required. With no on-train staff, platform screen doors (PSD) will be fitted to control the platform train interface risk. These will be 1.7 metres high and provided by Gilgen Door systems, the company that installed them on Paris Metro line one when it was converted to UTO.

Signalling will be the Communications Based Train Control (CBTC) system that Ansaldo has supplied to Copenhagen, Milan and Stockholm. Car-borne Controllers (CC) calculate the train’s position using a tachometer which records distance travelled since the last track balise and transmits this to the Zone Controller (ZC). This determines movement authority limit for each train and advises each train’s CC of its limits. The CC then brakes as required and enforces speed restrictions. It also provides Automatic Train Operation (ATO) and controls the train’s doors and other systems.

The ZC also controls the Wayside Standard Platform (WSP). This operates and responds to infrastructure-based equipment such as platform doors, platform alarm buttons, point motors and indicators.

Other aspects of the system are the FTM (fault and trouble management) alarm management system, HERMES. This uses the timetable, a performance management system (PMS) and iVENCS control software from ASL to manage passenger-related infrastructure such as CCTV, information screens and station assets. When a train is due to enter service, HERMES instructs the WSP and ZC via the FTM. The WSP then sets the points from the stabling sidings to the tunnel and the ZC instructs to CC to move the train at a safe speed.

Depot enhancements

A new Operational Control Centre (OCC) will be built at the depot to house the signalling and control system, train control and driver simulators, and incorporate best security, safety and ergonomic practice. The depot will gain a wheel lathe so wheelsets will no longer be sent away for tyre turning. A new fully automatic, UTO-compatible wash plant will also be provided.

The depot throat will be realigned to provide free UTO access to the stabling sheds. However, trains will be manually driven in the maintenance shed which will have a driver interface platform at its entrance. Trains will arrive here under UTO so a driver can enter the train to drive it by means of a flip-up control panel, provided at each end of the train.

The delivery and commissioning of these trains and their transition to UTO is a demanding programme. As the trains are four-foot gauge, Stadler cannot do any dynamic testing before delivery. Fortunately, SPT has a 760-metre long test track which was laid during the 1979 modernisation on the track bed of the Govan branch line which closed in 1966. Willie explained that Stadler will provide a construction depot and store adjacent to this track, which will be fitted with a CBTC system and a PSD-fitted platform.

Impression of Hillhead station with platform screen doors - Use at least one of the impressions

Service introduction

This facility will be used to assemble and test the articulated trains. It will be under Stadler’s control and segregated from normal operations. Before entry into service, test mileage accumulation will require these new trains to run through the Subway tunnels at night when there is no public service.

The first train is expected to arrive in Govan from Switzerland in 2019. By this time signalling control and communication systems will have been installed. It is likely to be another year before the new trains enter passenger service. When they do, trains will be manually driven from a temporary cab created by a partition wall that will be removed after UTO starts.

As platform screen doors will be controlled by the CBTC system, they will only be installed once all the new trains are in service and the current trains are withdrawn. Once the PSDs have been installed, it will be possible to introduce UTO.

UTO offers many benefits including the flexibility to introduce additional trains for short periods to move exceptional crowds. If required, the normal four-minute headway can be reduced to as little as 90 seconds, something that will no doubt be appreciated by the thousands of Rangers fans who use the Subway’s Ibrox station to get home from a match.

Introducing the first UTO service in the UK is a challenging project, not least in respect of the approval process for which SPT is in constant contact with the ORR. DfT is also being consulted about cyber-security. SPT has very close ties to all metro operators across the world through its membership of UITP and is constantly learning from other operators which have converted to UTO, in particular the Paris Metro.

SPT expects to have its UTO trains operating in 2021 to bring significant business benefits and customer improvements. No doubt the diminutive new Subway trains will also attract much attention and might perhaps encourage standard-gauge operators to follow the SPT’s trail-blazing approach to train operation.

Written by David Shirres