It is now approximately a year since Balfour Beatty won the contract from Centro to extend the Midland Metro light rail line by 1.3 km through central Birmingham as part of a £128 million project to increase capacity. A general outline of the extension, and its route down Corporation Street to Stephenson Street and New Street station, was described in issue 101 (March 2013) of The Rail Engineer.
That article also mentioned the new trams that will not only run on the new extension but also on the whole network. Spanish train manufacturer CAF (or Construcciones y Auxiliar de Ferrocarriles to give its full name) has now started construction of 25 new Urbos 3 trams that will replace the current fleet of 16 Ansaldo Transporti trams which have been in service since 1999.
Spanish success
CAF is an international leader in the design, manufacture, and maintenance of equipment for the railway industry. It was founded at the beginning of the twentieth century and now has a presence in 25 countries and is involved in 45 urban transport projects throughout the world (high speed, intercity, suburban, underground, tram and light underground). Research and development is a priority for CAF which has technological centres in six locations in Spain.
The Urbos 3 light rail vehicle was developed from the successful Urbos 1 and 2 which provide trams for services in Bilbao, Malaga, Vitoria, Seville, Edinburgh and Antalya. Urbos 3 boasts numerous improvements and, to date, has been ordered by, and delivered to, light rail and tram networks in Spain, Brazil, France and Sweden. The first vehicles are due for delivery this autumn and, starting next year, the new trams will operate on the current route from Snow Hill to Wolverhampton and then over the extended line to New Street when it becomes operational in 2015. They will provide a service of 10 trams per hour in each direction with an increased capacity of 210 passengers per tram compared with the current 156.
To accommodate maintenance and servicing of the new fleet, the depot at Wednesbury is being expanded by Morgan Sindall under a £13.8 million contract. The work includes a 42 metre extension to the main building, additional maintenance berths, four more stabling sidings and a separate testing and commissioning building. A new sub-station will be required and there will be upgrades to the overhead electrification and telecom infrastructure. Completion is planned for the middle of 2013.
Tram design
The new Midland Metro Urbos 3 is a standard (1,435mm) gauge, 2.65 metre wide, bi-directional, double-cab ended tram with a low floor throughout. The vehicle consists of five segments with four articulations. Three of the modules (C1, R and C2) are mounted on bogies and the other two modules (S1 and S2) are suspended. The overall length of the tram is 33 metres, 9 metres longer than the existing Ansaldo stock, and it has a maximum operating speed of 70km/h (44mph).
The modular design of the body shell combines low weight with simpler and quicker manufacturing processes. The majority of the elements are made of light aluminium alloys and extruded sections. These are complemented by high strength carbon steel in the C and R modules and composite components in the suspended S1 and S2 modules.
The bogie is of proven design, as used in all CAF low floor trams, having independent rotating resilient wheels. The bogies under C1 and C2 modules are powered with one traction motor per wheel, whilst the intermediate bogie under module R is a trailer. The bogie frame is made of cast steel and welded plates with a double primary and secondary suspension system.
The vast majority of equipment is installed on the tram roof, making it easily accessible. This includes the traction and auxiliary converters, braking resistors, pantograph, HSCB (high speed circuit breaker), battery, saloon and cab HVAC (heating, ventilation and air-conditioning) systems. This ease of maintenance, together with the lightness of the equipment, will reduce the consumption of resources and energy during the tram’s working life.
In the event of a failure to part of the traction system, there is sufficient capacity to allow the tram to continue in service as long as it retains
75% of its total capability, a feature which reduces the risk of service disruption.
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The tram is not expected to operate in multiple. However, in a recovery situation, one tram loaded with passengers at a density of six passengers/m2 is able to rescue another failed, empty tram under any track condition and with gradients up to 8%. For this purpose, the vehicle has an emergency folding coupler at each end, stowed behind the body end fairing, and an umbilical cord for communication and emergency braking.
The tram’s braking performance meets the requirements of EN 13452- 1, with a deceleration of 1.2m/s2 provided for service braking and certain emergency cases, while a deceleration of 2.8 m/s2 can be developed on application of full emergency braking.
There are three separate braking systems on the tram:
»  Electro-dynamic regenerative brake (EDB): the braking method used in service braking. This either returns power to the overhead wiring or dissipates it by the rheostatic resistors;
»  Hydraulic friction brake (FB): using one brake disc and calliper per wheel, this is utilised in service braking only to blend at high speed and during the EDB fade out stage at low speed. It has a major role under emergency brake demand and, together with the Magnetic Track Brake, guarantees the minimum secure braking of 1m/s2;
»  Magnetic Track brake (MTB): two per bogie, used for emergency braking only. Sanding is available at the leading bogies and applies automatically when low wheel / track adhesion is detected. The wheel slide protection (WSP) system on all bogies automatically adjusts the traction/braking effort in low friction conditions, both in traction (slip) and when braking (slide), to optimise performance
Passenger comfort
The total capacity of the tram is 210 passengers (54 seated + 156 standing). The overall accessibility criteria meets with the requirements of the Rail Vehicle Accessibility Regulations (RVAR) 2010.
Seats are specifically designed for daily use being comfortable, modular, individual, interchangeable, vandal proof and lightweight. The interior arrangement offers rapid access and egress of passengers to/from the tram through a sliding-plug door system. The overall layout provides for the continuous movement of passengers throughout the saloon.
Full HVAC systems are provided for both cab and saloon areas. In addition, passenger information and CCTV systems provide on-board, automated audible and visual information (through LED & TFT displays
and speakers). CCTV surveillance and on-board communication systems provide security for passengers and staff at each door.
Less able passengers are catered for by the 100% low floor which is only 350mm above the track, including the door access area. The gap between platform and tram is minimised to allow easy wheelchair access and two specific areas for the disabled are provided strategically close to the doors. Handrails are provided that allow safe movement through the tram and the support fixings are colour contrasted.
The CAF Urbos 3 tram ensures passengers have a good level of ride comfort and low noise levels of 70dBA internally and 79dBA externally at 60km/h. CAF has collaborated over the aesthetics and styling with Avant-Premiere, a company which has an excellent reputation and experience in the design of rail and transportation systems.
The tram is fitted with an event recorder (black box) which records the tram activity and can be interrogated in case of any incident. Also fitted is a passenger counting system while the tram control and monitoring system (TCMS) controls the connection, disconnection and operating modes of the auxiliary systems. It also coordinates and manages the flow of information along the tram and its systems, and informs the driver (through a display screen) of the tram’s status in real time.
Catenaryless capability
The Urbos 3 tram is fitted with passive provision for the future upgrade and installation of an autonomous power supply system (ACR – Acumulador de Carga Rapida), based on a design utilising both supercapacitors and batteries. These will increase the amount of regenerated energy as the system operates, recovering and storing the tram’s kinetic energy produced during braking operations. The result is a significant increase in the system’s efficiency as the energy stored during braking can be used again later, with savings of around 20%.
In addition, ACR can provide the tram with power to run along short sections without overhead wiring. Both the Seville and Zaragoza networks operate in this way, running without overhead wires in the historic centres of both cities. The Urbos 3 trams in Zaragoza cover five sections without wires – a total distance of 2km.
Every platform along the existing route has been modified to accommodate these new longer, and wider, trams. This work was carried out during a two-week closure at Easter 2013 and will enable both old and new trams to operate during the changeover period.
No other interface issues are envisaged between the Urbos 3 and the Midland Metro Network. The tram is capable of operating reliably to meet the required Mean Distance between Failures target, set for the annual average distance of 95,000km per tram.
CAF is aware that its industrial activities can affect the environment, so the company’s general policy includes environmental protection as one of its priority objectives. To this end, the CAF group owns a hydroelectric plant, integrates solar energy panels at its plants and operates in renewable energy using solar and wind energy. As a result of this effort, CAF has developed the world’s first verified Environmental Product Declaration (EPD) – The Green Yardstick – for the Urbos 3.
It really will be a green tram.
