January 2006 Issue 14

Strathclyde Passenger Transport (SPT) Glasgow Subway Automatic Train Operation (ATO) Obsolescent Analogue To Revamped Digital System

By Ed Gerrard MSc CEng FIRSE MIEE and Les Lyman BSc

Introduction Carrying out a technology refresh on train systems that have been operational for over 15 years provides a challenge to both developer and operator alike. Applying digital technology where previously analogue control systems held sway allows features and novel concepts to be implemented in a relatively short timescale with extensive configurability, adaptability, diagnostics aids and remote monitoring which would have been impractical and costly with analogue technology. This refresh has been successfully achieved in Glasgow - once renowned for its train building - now for its innovative Automatic Train Operation system. Glasgow Subway Background Carrying more than 13 million passengers a year, the Subway is a crucial link in

Glasgow's transport infrastructure. It comprises single inner and outer loop tunnels with a route length of 10.4 km. Opened in 1896 it has undergone several modernisations during its existence, the last full refurbishment being completed in 1980. The passenger carrying lines are' entirely underground. The Depot at Broomloan is on the surface and ramps exist to connect to the Tunnels.

The rolling stock of the Subway consists of 33 motor cars built by Metro Cammell in 1978, and 9 trailer cars built by Hunslet-Barclay in 1992. Both motor and trailer cars have collector shoe gear to operate 600 V equipment on the cars. "Each car runs on two four-wheel bogies of conventional design albeit with a non-standard gauge . Traction and braking

control on the motor cars is electro-mechanical; an automatic camshaft controller is used for connecting the motors in the traction and braking configurations. The braking system is a combination of electro-pneumatic and rheostatic and is analogue controlled. The modes of driving are 'Automatic', 'Manual Protected' (by Trainstops) and 'Restricted Manual' (top speed 25 km/h). The normal mode for passenger operation is 'Automatic'.

Glasgow Subway was re-signalled in 1996

(article E J Gerrard September 1997) and thenew signalling system has proved reliable, and of course safe. One major system that was introduced at the 1980 modernisation was Automatic Train Operation (ATO), however at the time of re-signalling in 1994 it was considered that a few additional years could be squeezed from the very successful train carried analogue equipment that comprised the ATO Auto driver and its associated trackside equipment. By the late 1990s it was becoming extremely difficult to obtain components to repair failed cards and the reducing number of serviceable ATO Auto drivers was becoming critical to maintaining the required service. ATO had been mandated by HMRI as a condition of driver-only train operation so the replacement of the original ATO became imperative.

Hyder Consulting were chosen by

Glasgow Subway to prepare the new ATO Performance and Functional specification for the replacement digital ATO and to act as project manager and technical advisor during the implementation contract.

N E W S 1

IRSE

Agenda N E W S

Basic ATO Requirements From a functional and performance perspective the original ATO system met the operational requirements of the Glasgow Subway service, and was a credit to the original designers. The project team's task was to retain and improve on the existing functionality and performance of the old system, whilst providing system enhancements that would exploit modern technology for operational and maintenance improvements within a prescribed budget. One major consolidation was the incorporation of the Wheel SlipSlide (identified as WASP) functionality into the new digital ATO Unit to replace the original obsolete analogue WASP Unit. The primary functions of the new ATO system include:

• Speed Regulation. • Accurate automatic stopping at

stations and intermediate signals (and automatic restart at intermediate signals).

• Rollback protection. • Auto calibration for wheel diameters. • Slip/slide detection and correction.

By utilizing digital hardware and software technology more secondary functionality could be implemented to provide a more robust ATO system and allow a much more intrusive and extensive analysis of operational performance than was previously possible.

The original and replacement ATO systems are of the intermittent type; whereby communication between trackside tags and train carried antenna is established at a number of discrete locations. These discrete tag locations are principally on the approach to a station or intermediate signal, to provide markers for accurate stops. There are also tags at station starter signals and intermediate signals for manual or automatic starts and at some locations for uploading train information to a central server. Other discrete tag locations are where permanent or temporary speed restrictions are required in the running lines of the particular circle.

2 I s s u e 1 4 J a n u a r y 2 0 0 6

IRSE

Agenda N E W S

incorporate proven hardware that was commercially available off-the shelf as far as practical with the ability to be supported for a 20-year target lifetime. Comprehensive software development and test facilities were essential to support the necessary application development. To manage the onboard ATO processing and station start-permit tag, the Siemens S700 PLC range was chosen based both on their track record and their suitability for the environment in which they would be operating. Software support and an upgrade path for these products used in the ATO installation are expected for theprojected 20 years of operation. The Siemens MOBYV industrial communications system provided the track-car communications system. This comprises a managed antenna on the underside of the train and unmanaged trackside preprogrammed tags giving the functionality for train stopping. At the front of each station platform a managed start-permit tag is provided to communicate the displayed signal aspect to the ontrain ATO Unit. These start-permit tags also provide a secondary function, that of being the means by which the train communicates the status of itself and all trackside tags (that it has passed over) up to the

The specification called for the highest standards in hardware and software. Hardware specifications for temperature, vibration and EMC are to accepted internationally recognised railway industry standards. The train-carried and station-based ATO software is designed to SIL-2 in accordance with the railway industry guidelines for safety related software. A full systems assurance and qualification programme was specified for the implementation phase.

Engineer support is provided through an Engineer's Terminal that connects directly into the ATO train carried unit. This allows the operation of the ATO unit to be monitored in real-time whilst the train is running, to configure the train ATO unit or to provide a data logging facility when investigating operational and performance problems.

Tenders for the implementation of this project were called through the European Journal. Mott MacDonald (MM) was commissioned in July 2000 as principal contractor to design, develop, install and commission the replacement ATO system. ATO System Product ChoiceThe technology chosen had to

Trackside tags are passive battery powered RF devices which store information on their location and their function (braking marker or speed restriction) that is communicated to trains on demand as the train passes over them.

To initiate the movement of a train from a station, the operator first closes the doors and then presses the two 'Auto Start' pushbuttons, provided an 'Auto Ready' (permit to go) signal from the trackside tag has been received. The train then accelerates up to a maximum permissible speed of 54 km/h unless it is constrained by a permanent or temporary speed restriction, which regulates the train speed to 15, 25 or 35 km/h as appropriate. A subsequent speed controlling tag may remove the speed restriction or change the speed limit, as circumstances require. The train operator has the target speed displayed on the in-cab speedometer.

At the approach to a station, the train ATO unit detects an outer fixed tag (1 st Braking Tag) and at the appropriate 'distance to stop' for the prevailing speed starts its automatic station stop. The automatic stop is then refined by another inner fixed tag (2nd Braking Tag), located 50 metres from the station correct stopping position. The ATO unit applies a programmable braking profile with a deceleration rate target of 1 ms. The train station stopping accuracy specification for this project is +/-750 mm about the correct stopping point. This had to be met on 99.9% of occasions within a distribution curve having a standard deviation of +/-350 mm. Two other important operational performance criteria, imposed in the performance specification, related to the final stopping jerk rate for passenger comfort and inter-station run times using the ATO mode of operation. At three stations (Govan, Ibrox and Buchanan Street), the Auto-Ready start-permit tag also uploads train operating data and trackside tag status data back to a Remote Monitoring Terminal (RMT) at the Broomloan depot, for analysing train and trackside faults associated with the ATO operation by the Rolling Stock Maintenance Engineer.

3 I s s u e 1 4 J a n u a r y 2 0 0 6

IRSE

Agenda N E W S

remote monitoring terminal in the depot. Siemens, in the Berlin Underground, had

previously deployed these tags/Antennae and therefore field data was available to support their use in this installation.

ATO Unit Development and Implementation The ATO Onboard Controller drives the train in 'Automatic' from each station maintaining the appropriate speed restrictions, and applying aprogrammable braking profile so that the train comes to a smooth stop at the correct stopping point in the next station. In order to be sure that a trackside tag has not failed, the onboard controller holds a map of the subway locating each of the trackside tags and its corresponding function. In this way, the train ATO predicts when a tag is expected and confirms its location when it detects it. This means that the train always knows which circle it is in and it's location around that circle. It also means that the train can continuously confirm its distance measurement (derived from its speed measuring algorithm) and automatically correct for wheel wear. The trains will operate safely in a degraded mode using its built-in map even when all permanent trackside speed restriction and braking tags have failed.

During system testing it was found that the inconsistency of stopping accuracy, position and required braking demand was sufficient to require refinements to the basic station stopping control scheme. The concepts of automatic positionalcompensation and subsequently automatic brakingcontrol parameter adaptation were successfully introduced. When the train has stopped in a station, the amount of over/under-run at that stop will result in a small adjustment to the target stopping position/distance before the holding brake is applied to provide constant braking into the final stop. Similarly, the characteristics of the final braking demand during the final approach into the stop are monitored to automatically adjust the braking profile over the last 50 m of the stop in order to standardise the ride quality into the final stop. To protect from these two algorithms fighting each other, the braking parameter adjustment is only permitted to occur when the achieved stopping position at that stop is within 0.25 m of the correct stopping point. Another feature of the adaptive control scheme is that the journey time around the circles is automatically optimised within the parameters allowed for passenger comfort. These adjustments only take effect on the next stop intothat station.

4 I s s u e 1 4 J a n u a r y 2 0 0 6

IRSE

Agenda N E W S environment. A number of modifications were made to the ATO prototype software during trial running. These modifications were strictly controlled and logged. Once the prototype had passed the range of acceptance tests, the rest of the fleet of 33 Cars were fitted. A rigorous change control procedure was adopted throughout the migration of the new ATO Units into service .

As part of the Systems Assurance an ATO system reliability, availability and maintainability (RAM) process was instigated. Following the completion of commissioning of the Trackside and the first accepted Car with the new ATO, a Defect Reporting and Corrective Action System (DRACAS) procedure was instigated. Under this system, operational time and failures were recorded. Failures were analysed, and corrective action undertaken where necessary. From therevenue operating time period and the failures during the Commissioning and defect warranty period a MTBF for an individual ATO unit has been calculated as 26 700 hours at a 90% confidence. For trackside equipment (103 permanent trackside tags + 16 station PLCs) the MTBF as been calculated as 1 974 hours with a 90% confidence. The reliability and overall operational performance of the new ATO system has proved to be exceptional. . During the ATO installation period

operators and maintainers had formal training on the new system (from an operating and maintenance perspective).

The replacement ATO system was formally taken over by SPT on 11 August 2003 for a formal twelvemonth defects liability period.

Credit for this excellent project outcome must rest with the relativelysmall combined SPT, Mott MacDonald and Hyder ATO project team. Teamwork, dedication, commitment and perseverance resulted in bringing this technically challenging task to a successful completion within an economical budget and timeframe.

Photographs provided by SPT and Mott MacDonald

analysed and re-configured. This ET allows on-line diagnosis of equipment faults and train characteristics; algorithms can be tuned or even deselected easily whilst the train is running. The built-in data logging capability allows a train to be operational in passenger service for an 18-hour day whilst the ATO unit inputs, outputs and control parameters are logged. The data can be analysed by exporting it into a spreadsheet or database tool. The status of the onboard ATO equipment, and that of trackside tags with which it has communicated, is uploaded at the three stations which are networked to the main depot. Warnings can then be presented on screens in the depot to aid early warning of possible future failures and facilitate timely maintenance activities. Further diagnostic facilities have been introduced through the remote monitoring terminal to detect when trains are being driven manually or when the driver is required to override the automatic braking for any reason. These allow maintenance and operations engineers to anticipate potential problems associated with particular trains, with trackside tags or with driving practices (that can highlight undesirable train performance characteristics such as ride quality which cannot be otherwise be determined by the ATO unit) . ATO System Testing and Commissioning For ATO unit factory testing a basic Train Simulator was used. To assist in the initial A TO site development testing, SPT reinstated the Broomloan Depot Test Track that had been used in the previous development of the analogue ATO unit 20 years earlier.

Migration of the replacement ATO into operational service was

undertaken in a stepwise manner. Initially the new ATO station and trackside equipment was installed and commissioned to operate in parallel with the original ATO system.

One driving car was fitted with a prototype ATO Unit for trial operation in the underground

The adaptive nature of the control scheme allows variances in the operation of the traction and braking systems on the cars comprising the train to be taken into account. It also allows automatic compensation (within permitted bounds) for non critical fault conditions, so keeping the trains in operational service, without reducing the operational availability of that train, until such a time that maintenance engineers can make the appropriate adjustments.

The speed detection is driven from four original (up to 20 years old) tachometers located one on each axle of the driving car. Not having a diverse means of measuring the train's speed means that there is inevitably a degree of uncertainty about the actual train speed and consequently the precise location of the train. The ATO control scheme includes detection of noisy signals (due to cabling, connection or detector faults) and automatically excludes them from the speed determination algorithm whilst they are considered noisy. A novel enhancement has been implemented that detects low speed drop off or delayed pick up of these signals and similarly automatically excludes these signals at low speed from the actual speed determination. These probe signal characteristics are reported back to the remote monitoring terminal to allow the maintenance organisation to determine when these probes or their connections require to be overhauled. In order to minimise the effects of errors in speed (distance) determination, the ATO Controller's map of the system is used in conjunction with the trackside tags to constantly correct the known position of the train every time a tag is detected. SPT have undertaken a programme of refurbishment of the tachometers, their cabling and connections; all of which contribute to the quality of the signals provided to the ATO Unit.

ATO Unit Diagnostic and Monitoring Tool An Engineer's Terminal (ET) has been developed which uses a graphical user interface to allow the onboard control scheme and its various algorithms to be monitored,

5 I s s u e 1 4 J a n u a r y 2 0 0 6

N E W SIRSE

Advertisement

6 I s s u e 1 4 J a n u a r y 2 0 0 6

N E W SIRSE

Agenda

7 I s s u e 1 4 J a n u a r y 2 0 0 6

8 I s s u e 1 4 J a n u a r y 2 0 0 6

N E W SIRSE

Agenda

9 I s s u e 1 4 J a n u a r y 2 0 0 6

N E W SIRSE

Agenda

IRSE

Advertisement N E W S

10 I s s u e 1 4 J a n u a r y 2 0 0 6

11 I s s u e 1 4 J a n u a r y 2 0 0 6

N E W SIRSE

Agenda

12 I s s u e 1 4 J a n u a r y 2 0 0 6

N E W SIRSE

Agenda

IRSE

Agenda N E W S

13 I s s u e 1 4 J a n u a r y 2 0 0 6

14 I s s u e 1 4 J a n u a r y 2 0 0 6

N E W SIRSE

Agenda

N E W SIRSE

Advertisement

15 I s s u e 1 4 J a n u a r y 2 0 0 6

v

The signals depicted this month are used by British drivers every day and many IRSE members will have travelled on trains signalled by them. They are two of the non-franchissable signals controlling departures from the Eurostar platforms at Gare du Nord in Paris.

The normal vertical arrangement of the main aspects of an SNCF colour light signal has been used for c106 on the right; this signal controls movements out of the easternmost of the group of four platforms. The overbridge, which carries a street and a Metro line, is at an angle to the tracks below. The effect of this is that Eurostars in the other platforms are closer to the overbridge, the more so the farther to the west (left of the photo) they are berthed.

The three signals (of which c105 is the easternmost) controlling departure from the other platforms are of this different form with the aspects arranged in a square. This is presumably for sighting reasons, so that the highest aspect can still be seen from the Eurostar cabs close to and below them.

Interesting Signals No.57

IRSE

N E W S Jokes of the Month

Interesting Signals & Jokes

Honesty On the Internet !!!

Paris Care du Nord By Phil Hingley

Where've your Dog been????

What does a WIFE think about a husband !!!

16 I s s u e 1 4 J a n u a r y 2 0 0 6

17-19,Feb 06

Hainan Railway Ferry IRSE Welcome all IRSE members

May 06 Shen Zhen Nuclear Power Plant IRSE Welcome all IRSE members

Jul 06 Airport Control Tower IRSE Welcome all IRSE members

Sep 06 Cheng Du Metro Line 1 Visit IRSE Welcome all IRSE members

Nov 06

GuangZhou Metro Line 3 Visit

IRSE Welcome all IRSE members

IRSE

Activities

2006 Activities of IRSE (HK Section)

N E W S

17 I s s u e 1 4 J a n u a r y 2 0 0 6

IRSE

Technical Visit N E W S

Itinerary: 17 Feb. – Bus from Shenzhen – Guangzhou

- 10:26 pm Train Departure from Guangzhou – Haikou 18 Feb. - 10:30 am Arrival in Haikou Visit Haikou Railway Station, City Tour, stay in 4 stars hotel. 游萬綠園; 假日海灘; 國家 4A 級熱帶海洋世界; 海南特產大世界. 19 Feb. – 10:20 am Departs Haikou Airport, Arrival to Shenzhen Airport at noon, then travel to Lu Wu, End of the trip. Cost : HK$1,200.00 per person (Option: for single room additional of HK$400) Standard: 3-4 stars hotel; including breakfast, lunch and dinner, normal sight seeing tickets and travel insurance. The visiting group is limited to 36 persons. Please make your booking in advance. First come first served basis. Booking Arrangement: Kindly post your cheque payment to IRSE HK at the below address. Please make payable to “The Institution of Railway Signal Engineers HK Section”. Deadline for booking is on 18th of January 2006. In addition, please provide your Chinese name and Return Permit No. for flight booking. Postage Address: Ms. Catherine Chan

10/F., MTR Tower, Telford Plaza Kowloon Bay, Kowloon Hong Kong

For Enquiry: Mr. Sung Yuen Fat - Mobile no. 98196106 Mr. Francis Hui - Mobile no. 94387293

18 I s s u e 1 4 J a n u a r y 2 0 0 6

Happy Birthday! Our best wishes to the following IRSE (HK Section) members.

Members Corner IRSE

N E W S

19 I s s u e 1 4 J a n u a r y 2 0 0 6

進一步連繫 多一分親近

IRSE

進一步連繫 多一分親近 One Link Further One Step Closer

Advertisement N E W S

20 I s s u e 1 4 J a n u a r y 2 0 0 6

IRSE

N E W S Agenda

21 I s s u e 1 4 J a n u a r y 2 0 0 6

Message from Chairman Franco Fabbian:

As we look forward to a New Year of opportunities I would like to wish you all a Happy Chinese New Year.

Franco Fabbian Chairman of IRSE HK

It is my honor to continue my service as Chairman to IRSE Hong Kong section. On behalf of the committee, I would like to express my sincere appreciation to all of you for your consistent support and cooperation in the past, and wish you continue in future. 2006 is another challenge year to us, we need constantly achieve high as in the previous years. In addition, the institution is aiming to extend its services into China and broaden the co-operations on academic training with local education institutions, such as IVE. I foresee the amount of work will increase significantly and therefore welcome volunteer members to join in the working committee as a new source of strength and inspiration to realize our mission and symbolize our commitment. Please kindly either respond to me or Francis Hui via email irse.hk@gmail.com. Together we can build the future for IRSE Hong Kong.

.

IRSE

N E W SEditor Column

On this New Year day, I wish you all every happinessand prosperity. And with it , all the new unknowns and wishful wants and resolutions to be bigger , better , best . So lets all continue to work together for a brighter 2006. Invoking GODS BLESSING and assuring you of my prayers, I remain. Happy Chinese New Year to all and to all a good Cheer! Sincerely yours, Myla Pilarta-Li Editor

IRSE News Letter is published monthly by Institution of Railway Signal Engineers (Hong Kong Section). All rights reserved. Photocopying or reproduction in any form without the written permission of the publisher is strictly prohibited. While every effort has been made to ensure accuracy, no liability is accepted for errors or omission herein. The Team Players Myla Pilarta-Li Francis Hui KC Lam Enoch Li Lawrence Tam Ground Control 10/F, MTR Tower, Telford Plaza, Kowloon Bay, Hong Kong Advertising Info Tel: (852) 2993 3264 Fax: (852) 2993 7728 Email: mylairsenewsletter@yahoo.comWebsite: http://www.irse.org.hk/

22 I s s u e 1 4 J a n u a r y 2 0 0 6

進一步連繫 多一分親近

IRSE

進一步連繫 多一分親近 One Link Further One Step Closer

Advertisement N E W S

23 I s s u e 1 4 J a n u a r y 2 0 0 6