The Testing Programme of the prototype TRAM Light Rail Vehicle.

1.0 Introduction

Following the successful testing of the TRAM1 Research Ltd design bogie and electrical traction package, a full size Light Rail Vehicle has been designed and built. The completed 29m long TRAM Light Rail Vehicle (LRV) was delivered and fully assembled in Blackpool in late 1997. Since then tests have been undertaken in live operations on the Blackpool Tramway, and modifications to improve performance have taken place.

Prototype tram in Blackpool

2.0 Description of the prototype TRAM LRV

2.1 General arrangement

The prototype TRAM LRV is 29m long, 2.4m wide to fit the swept path of the Blackpool Tramway, and 2.9m high, with two 4 wheel power bogies, one at each end of the LRV, and a 2 wheel unpowered truck at the central articulation supporting the two main body parts. Each powered bogie is driven by a 3 phase ac motor located in the body under the driver's cab. The traction is transmitted between the motor and the wheels by a propeller shaft, on which is mounted a disc brake. All inverter and control equipment is located within each driver's cab. There is no equipment within the main passenger saloons.

2.2 Traction power

The traction power is provided by a flux vector 3 phase ac inverter, software programmable to give operator specified speed, acceleration, jerk and braking performance. The inverter is controlled by a micro processor based Programmable Logic Controller (PLC) from a joystick in the driver's cab. Braking down to standstill is regenerative, without the need for friction brakes. Regenerated current can be fed into the overhead line, if receptive, and then used by an adjacent accelerating LRV. Alternately the regenerated power is dissipated in on board resistors, which in the prototype LRV are roof mounted.

2.3 Multi-plex control

The PLC provides a multi-plexing system to enable all electrical equipment to be controlled from a 2 wire main ("fly by wire") along the LRV. This means that subsequent LRV alterations do not need a full vehicle rewiring. Doors, lights etc. are all controlled via the PLC, which has a priority operation algorithm to ensure that vital functions always take precedence.

2.4 Braking

Service braking is via the regenerative use of the ac traction motors. There is a hard wired foot pedal brake system, which applies the motor shaft disc brakes and 4 electro-magnetic track brakes for additional or emergency use. There is also a PANIC Emergency Button system, which applies all braking systems together and shuts down the power to the main inverters.

2.5 Suspension

The LRV is supported on 6 air bags, which are self levelling to ensure that the low floor is always 300 mm above rail level. Each bogie supports two axles compliantly to ensure good rail rail holding and to maximise tractive adhesion for all driving wheels, which rotate independently. Air bags are fitted with dampers to minimise bounce and eliminate resonant frequency bumping. Finally all ten wheels have the newly developed TRAM resilient cushions, which provide the primary suspension for the LRV.

2.6 Auxiliaries

All main and auxiliary equipment is based on 415V 3 phase ac, 250V 1 phase ac or 24V dc power. The ac powers the air compressor, battery chargers and some other equipment sourced from industrial suppliers. The 24V dc powers doors, lights and other equipment sourced from HGV and PCV suppliers.

2.7 Body Structure

The body is built out of stainless steel tubing welded into a chassis-less structure, which is strong, rigid and durable.The LRV flooring is mounted directly on the body frame. The window glass is also directly bonded onto the steel frame. The prototype body has thermal insulation but to reduce costs there is no acoustic insulation.

2.8 LRV Interior

The vehicle interior has been fitted out in a middle range quality of seats, fixtures and fittings, to provide an impression of what can be achieved within the large vehicle envelope available in the TRAM LRV. Clearly system operators will specify colour schemes, fixtures and fitting to suit local requirements.

2.9 Power Collection

Power for the LRV is collected via a simple single arm roof mounted high reach pantograph capable of contacting the overhead line up to 7m above the track. For the Blackpool tramway the pantograph is mounted mid way between a bogie and the central articulation. On other systems the pantograph would be mounted directly above a power bogie. A 750V dc power cable runs from the pantograph fuses along the roof of both half cars to main circuit breakers in the drivers' cabs, and thence to auxiliary and traction power inverters. Other current collecting systems are possible and can be designed to suit customer preferences.

2.10 Crash resistance

Finally the cabs ends have crash resisting frames designed to absorb crash energy and protect the driver in the event of a frontal crash. The main traction motor under the driver also absorbs crash energy and rides down under the LRV. The cab is defined by a re-inforced resin moulding, which can be designed for operator preference to fit the LRV crash resisting frame.

3.0 Testing the prototype TRAM LRV

3.1 Structural tests

The prototype frame has been subjected to static deflection tests under simulated loading, to ensure that the calculated load bearing strength has been achieved.

3.2 Braking tests

The separate braking systems have been subjected to rigorous testing, including stopping a 40 tonne train. This involved the 18 tonne Blackpool Tramway engineering car towing the TRAM LRV. The brakes of the 22 tonne LRV were applied, easily stopping both the LRV and the engineering car in under 10 m. This train weight is greater than a fully laden LRV.

The LRV has been tested with only one motor available for regenerative braking. The remaining motor easily stops the LRV.

Downhill braking was fully tested at speed. The service brake stops the LRV without wheel locking or sliding. The electric regenerative brake stopped the LRV at 1.3 m/s/s, and the emergency brakes; disc and electro-magnetic track at 0.28 g (2.8 m/s/s).

The emergency braking system has shown itself to be 100% reliable under a variety of LRV. operating and track conditions.

3.3 Power tests

The LRV has been operated under its own power over the full Blackpool Tramway system, from Starr Gate in the south to Fleetwood in the north. This includes a variety of track forms, including open sleepered bullhead railed tracks, grooved rail tracks with paving slabs along the Promenade and grooved rail tracks set in tarmac paved streets in Fleetwood. There have been no operating problems from these different track forms.

The power tests have included single and double motor operation, power consumption under different conditions and restarting up hill. These tests have confirmed the calculated power consumption of the LRV at the full rate of acceleration, and averages about 600 Amps (or about 0.3 mW). This indicates considerable electrical energy savings over other contemporary LRV's. The power savings alone over the life of the LRV would probably pay for the full capital investment cost of the LRV. Further power savings can be achieved by the use of the regenerative braking current into a receptive over head line.

3.4 Failure tests

A number of failure tests have been undertaken to confirm fail safe operation. These have included loss of the return path for electrical power to track. Because the TRAM LRV uses ac drives, the LRV body does not become live at the dc overhead line voltage in the case of a return current path failure.

Failure of the air system leads to a full brake application and the LRV cannot restart until air pressure has been restored for braking and air suspension. An air system failure also leads to the sounding of a low air pressure siren in each cab.

Doors opening while the LRV is moving leads to a full brake application. Because of the interlock between doors and controller, the LRV cannot be started until all doors are fully closed. Warning lights on the driver's panel provide a further level of safety.

3.5 Clearance tests.

The LRV has been taken over all the tracks of the Blackpool Tramway to ensure that all swept path calculations are achieved in practice and that there is a safe distance between passing vehicles and fixtures along the tramway. This was demonstrated fully and safely.

3.6 Noise measurements

Interior and exterior noise measures have been undertaken. These show that the TRAM LRV is significantly quieter than other Blackpool trams and other large road vehicles. The independently rotating wheels and fully enclosed ebogies means that mechanical noise generation is minimised and retained under the LRV. With a full acoustic insulation package, further interior noise level reductions will be achieved.

The exterior quietness is achieved by the fully skirted body . The most noticeable exterior noise is the 3 kHz whistle from the modulation frequency of the main inverters.

3.7 HMRI tests.

3.7.1 HMRI Inspection

Some of the above tests were undertaken during an inspection by HM Railway Inspector (HMRI) on 1st and 2nd June 1998. Further tests included road traffic accident and pedestrian incident simulation to determine the safe operation of life guarding equipment . A dummy pedestrian was collided with but was deemed to have been saved by the life guard equipment, which prevents a pedestrian going under the LRV.

3.7.2 Outside features

The HMRI is also concerned about the overall safety of the LRV inside and out. The lack of protruding fixtures outside the LRV means that pedestrians cannot be accidentally caught and swept along the street. Similarly there is nowhere for youths to joyride by hanging on the outside. The doors have sensitive detectors and anyone trapped by the door closing leads to the doors automatically re-opening. The LRV cannot start until all doors are fully closed. Therefore passengers cannot be swept along if caught in the doors.

3.7.3 Inside details

Inside the LRV the details of the seats, fixtures and fittings have been agreed with the HMRI at the design stage. Extra hand holds were recommended during the inspection and subsequently fitted.

3.7.4 Emergency brakes

Emergency brakes tests, including stopping a towing tram under power, with a full train weight of 40 tonnes, were entirely successful and satisfactory. The "dead man's" handle feature on the master joystick was satisfactory, as was the foot pedal brakes and emergency button in stopping the LRV.

3.7.5 HMRI Approval

The HMRI visit resulted in approval being given for immediate full test operation and indicated that on completion of endurance and reliability operational tests, would on the recommendation of Blackpool Transport Services Ltd agree to revenue passenger service.

It has also been agreed that this approval will apply to clones of the TRAM LRV as a type approval for all UK systems. HMRI infrastructure approval is of course system specific.

4.0 Maintenance

No premature equipment failure or wear has been experienced. Maintenance has been confined to cleaning the inside and outside of the LRV.

5.0 Conclusion

The prototype TRAM LRV operating in Blackpool has completed a comprehensive battery of tests covering; safety, reliability and economic operations. These have shown that the design objectives and calculated performance have been achieved. The TRAM LRV is a passenger and environmentally friendly people mover.

© TRAM Research Ltd. October 1998