Tuen Mun – Yuen Long LRT

Traffic Control System

20th April 2007

Prepared by Michael Chiu

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Introduction LRT / Road Traffic Control System LRT Detection System Signal Operation Features of Traffic Signal Controller

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Introduction

The KCRC Light Rail Transit (LRT) was commissioned in 1988 and the system was further expanded between 1991, 1993 and 2003.

The current daily passenger volume is about 400,000 which serving Tuen Mun, Yuen Long and Tin Shui Wai of over 1 million of population.

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Tuen Mun – Yuen Long LRT System

In year 1988, the Phase 1 LRT/Road Traffic Control System was installed in Tuen Mun and Yuen Long Areas to provide priority traffic control for Light Rail Vehicles. The System was further expanded to Tin Shui Wai in years 1993 and 2003.

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KCRC Light Rail Transit (LRT)

T U E N M U N / Y U E N L O N G L R T P H A S E 22 /1 9 9 2 C O M M E N C E D PA S S E N G E R S E R V IC E

TUEN MUN / YUEN LONG LRT PHASE 19/1988 COM MENCED PASSENGER SERVICE

TIN SHUI WAI LRT 1/1993 COM MENCED PASSENGER SERVICETIN SHUI WAI LRT EXTENSION10/2003

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Basic Operation and Control Principles

• The Light Rail Vehicle (LRV)

• Vehicle actuated for road traffic

• Priority control for LRV

• suffer minimum delay

• pass through junction without slowing down

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T

LRT / Road Traffic Control System Schematic Diagram

Traffic Signal

Controller

LRT Interface

Unit

LRT Signalling System

LRT Interrogator

Unit

LRT Request

DetectorsLRT Request (max 8 nos.)

and Interrogator Fault Signals (max 2 nos.)

Traffic Controller Fault Signal (1 no.)

LRT Signal Lamps Drive (max 8 sets)

LRT Request (max 8 nos.) and

Interrogator Fault Signals (max 2 nos.)

Traffic Controller Fault Signal

(1 no.)

LRT Signal Lamps Drive

LRT Proceed Signal (max 8 sets)

Vehicle Detection Loops

Push Button Units

Lamp Drive to Vehicular and Pedestrian Signals

Note : If the period of a LRT request signal is shorten than 4 seconds, it will be treated as an artifical request

LRT Cancel

Detectors

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Detection System

Road traffic detection

• Inductive loop detector

• Infra-Red detector

• Demand Right-of-Way

• To Extend Green time to Preset Maximum Green

Pedestrian Traffic Detection

• Push Button

• Demand Right-of-Way

LRV Detection

• Individual LRV identity

• Request detector

• Cancel detector

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Inductive Loop Detector

Inductive Loop DetectorInductive Loop Detector

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Inductive Loop Detector

Concrete Slab

Inductive Loop Detector

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Alternative Vehicle Detector

Infra-red Detector

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LRV Request Detector

LRV Request Detector

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LRV Cancel Detector

LRV Cancel Detector

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LRT Signals

LRV Signal

Junction SpeedIndicator

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Braking time(A)

Intergreen(B)

Min. green(C)

Intergreen(D)

Firstdelay

Roadjunction

Flashing proceedperiod

Critical servicebraking point

LRVStopline

Prevent

Prioritydemand

Timing Periods of LRV on Approach to Stop Line

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LRT Detection System

• LRV Request / Cancel Detectors

• To detect the vehicle number and route number of every LRV

• LRT Interrogator Unit

• Processes the LRT request and cancel signals

• Create LRT request signals to traffic signal controller

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LRV Request Detector

• LRV request detector will be located at the latest position to permit the LRV to proceed through the junction without being stopped for traffic signals.

• The location of every request detector would be determined by :

1. LRV Speed Profile

2. Intergreen timings between phases

3. LRT Stop and track point

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• LRT Interrogator detects the vehicle number and route number of each LRV and produce a request signal for a particular LRV movement phase.

• The Interrogator stores information on any LRVs which passed a request detector and have not yet passed the junction and cancel detector.

• The request signal will be ended when the last requested LRT train reaches the cancel detector.

Process of LRT Request Signal

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LRT Proceed Signal

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Features of Traffic Signal Controller

• Provide inputs for :

• Maximum 8 Nos. of LRT requests, and

• Maximum 2 Nos. of Interrogator Fault Signals

• Provide output for :

• 1 No. of Controller Fault

• Total 15 sets of Lamp Drive, in which maximum 8 sets of Lamp Drive can be provided for LRT Phase

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Features of Traffic Signal Controller

Provide LRT Priority Mode

• LRV have priority in gaining and holding Right-of-Way over other vehicles

• Priority LRV demand will curtail the extension time of the current VA phases, and skip all the VA demands in order to move to the stage that constituting the demanded priority phase immediately

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Features of Traffic Signal Controller

Provide Priority Phase Non-fixed Phase Non-Latching Demand During Inter-stage Period Maximum Green Periods, consists of :

VA Maximum Green Period Priority Maximum Green Period Four sets of VA maximum and priority maximum

times are provided for each LRV priority phase

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Features of Traffic Signal Controller

• LRT first and second delay periods• Provide LRT first and second delay periods to delay

processing of LRV request signals.

• When LRT first delay starts, Detector Fault Monitoring (DFM) facility will be run to monitor the duration of that LRT request.

• During the second delay, a stage change is prevented except to the stage that constituting the specified LRV phase.

• After expiry of the LRV first and second delay, a priority demand will be inserted to the associated LRV Phase Movement.

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Features of Traffic Signal Controller

• LRT first and second delay periods• Provide LRT first and second delay periods to delay

processing of LRV request signals.

• When LRT first delay starts, Detector Fault Monitoring (DFM) facility will be run to monitor the duration of that LRT request.

• During the second delay, a stage change is prevented except to the stage that constituting the specified LRV phase.

• After expiry of the LRV first and second delay, a priority demand will be inserted to the associated LRV Phase Movement.

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Phase Compensation

• If a VA phase is curtailed by LRV priority, an extension of the VA maximum time of that VA phase may be introduced next time when it gains right of way.

• Four different sets of compensate timers can be configured in associated with the LRT phase to cope with the AM peak, PM peak, Off-peak and Fault Mode operations

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Extended Intergreen Period

• Extended Intergreen Period shall be run after an LRT phase under the following conditions :

1. If there is an outstanding LRT demand;

2. If there is an LRT fault, priority DFM or artificial request;

3. If the controller is in fixed time or manual modes.

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Extended Intergreen Period (Cont’d)

• Extended Intergreen Period shall be terminated when either :

1. The outstanding LRT demand has been cleared; or

2. The Extended Intergreen Period has been extended to its maximum value.

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Extended Intergreen Period (Cont’d)

• An optional facility (Flexible All Red Facility) can be provided for complicated junction with several LRV phases and LRV stages.

• The traffic controller can select 6 different Extended Intergreen periods in accordance with the phase to phase and stage to stage movements taking place.

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LRT First Come First Serve Facility

• In general the controller will serve the Priority demands in cyclic order.

• At some junctions one LRV approach may be used by 2 LRVs which turn in different directions at the junction, it may need to use First Come First Serve Logic to serve the LRV demands in the order of sequence of arrival.

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LRT Service Order Facility

The traffic controller will remember which V.A. stage was served before the priority stage, and, if there is a V.A. demand move to the next stage.

The stage sequence of this example junction would be

Stage 1=>Stage 2=>Stage 1=>Stage 3=>Stage 1=>Stage 4=>Stage 1=>Stage 5

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Detection of LRT Faults

• The traffic controller detects 3 types of LRT faults, including

- Interrogator Fault

- Artificial Request

- Priority DFM

• The traffic controller will also count the numbers of the LRT faults, and time the fault durations.

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LRT Fault Mode Operation

When LRT fault (Artificial Request, Priority DFM or Interrogator Fault) is detected, the traffic controller will enter Fault Mode Operation, and take the following actions :1. Disable priority operation for the faulty request.

2. Insert permanent demand to the faulty LRT phase.

3. Every time the faulty LRT phase terminates, the controller will insert Extended Intergreen Period and extend to the maximum.

4. Run the Fault Mode Plan (with shorter cycle time) when the Interrogator fails or serious LRT detector failures is detected.

The fault mode operation will be self-reset after the LRT fault has been cleared.

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LRV Signal Timings

Stop

R C30

Stop

1st Delay Green Proceed Flashing Proceed

ConstantJunction Speed

braking

Direction of Travel

LRV Speed Profile

Inter-Green

MinGreen

Inter-Green Braking Time

PriorityDemand

Prevent/2nd Delay

T T T

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LRV Speed Profiles P-way Alignment Diagram

Acceleration/Deceleration Characteristic Tables

Speed Restrictions at Curves

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Permanent-way Alignment Diagram

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LRV Acceleration/Deceleration Characteristic Tables

Target Speed

Initial Speed 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Initial

Speed

0 0.8 3.2 7.2 12.9 20.1 28.9 39.4 62.6 97.9 134.6 175.1 219.4 267.7 319.8 0

50 3.5 2.4 6.4 12.1 19.3 28.1 38.6 61.8 97.1 133.8 174.3 218.6 266.9 319.0 5

10 7.0 3.5 4.0 9.7 16.9 25.7 36.2 59.4 94.7 131.4 171.9 216.2 264.5 316.6 10

15 11.2 7.7 4.2 5.7 12.9 21.7 32.2 55.4 90.7 127.4 167.9 212.2 260.5 312.6 15

20 15.5 12.0 8.5 4.3 7.2 16.0 26.5 49.7 85.0 121.7 162.2 206.5 254.8 306.9 20

25 22.8 19.3 15.8 11.6 7.3 8.8 19.3 42.5 77.8 114.5 155.0 199.3 247.6 299.7 25

30 30.0 26.5 23.0 18.8 14.5 7.2 10.5 33.7 69.0 105.7 146.2 190.5 238.8 290.9 30

35 40.5 37.0 33.5 29.3 25.0 17.7 10.5 23.2 58.5 95.2 135.7 180.0 228.3 280.4 35

40 51.0 47.5 44.0 39.8 35.5 28.2 21.0 10.5 35.3 72.0 112.5 156.8 205.1 257.2 40

45 63.5 60.0 56.5 52.3 48.0 40.7 33.5 23.0 12.5 36.7 77.2 121.5 169.8 221.9 45

50 75.5 72.0 68.5 64.3 60.0 52.7 45.5 35.0 24.5 12.0 40.5 84.8 133.1 185.2 50

55 90.8 87.3 83.8 79.6 75.3 68.0 60.8 50.3 39.8 27.3 15.3 44.3 92.6 144.7 55

60 106.0 102.5 99.0 91.8 90.5 83.2 76.0 65.5 55.0 42.5 30.3 15.2 48.3 100.4 60

65 123.0 119.5 116.0 111.8 107.5 100.2 93.0 82.5 72.0 59.5 47.5 32.2 17.0 52.1 65

70 141.0 137.5 134.0 129.8 125.5 118.2 111.0 100.5 90.0 77.5 65.5 50.2 35.0 18.0 70

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

Target Speed

Acceleration / Deceleration Distance (in metre)

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LRV Acceleration/Deceleration Characteristic Tables

Target Speed

Initial Speed 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Initial

Speed

0 1.2 2.3 3.5 4.6 5.8 6.9 8.1 10.3 13.3 16.1 18.9 21.7 24.4 27.2 0

50 1.1 1.1 2.3 3.4 4.6 5.7 6.9 9.1 12.1 14.9 17.7 20.5 23.2 26.0 5

10 2.2 1.1 1.2 2.3 3.5 4.6 5.8 8.0 11.0 13.8 16.6 19.4 22.1 24.9 10

15 3.3 2.2 1.1 1.1 2.3 3.4 4.6 6.8 9.8 12.6 15.4 18.2 20.9 23.7 15

20 4.4 3.3 2.2 1.1 1.2 2.3 3.5 5.7 8.7 11.5 14.3 17.1 19.8 22.6 20

25 5.5 4.4 3.3 2.2 1.1 1.1 2.3 4.5 7.5 10.3 13.1 15.9 18.6 21.4 25

30 6.6 5.5 4.4 3.3 2.2 1.1 1.2 3.4 6.4 9.2 12.0 14.8 17.5 20.3 30

35 8.1 7.0 5.9 4.8 3.7 2.6 1.5 2.2 5.2 8.0 10.8 13.6 16.3 19.1 35

40 9.0 7.9 6.8 5.7 4.6 3.5 2.4 0.9 3.0 5.8 8.6 11.4 14.1 16.9 40

45 9.8 8.7 7.6 6.5 5.4 4.3 3.2 1.7 0.8 2.8 5.6 8.4 11.1 13.9 45

50 10.8 9.7 8.6 7.5 6.4 5.3 4.2 2.7 1.8 1.0 2.8 5.6 8.3 11.1 50

55 11.7 10.6 9.5 8.4 7.3 6.2 5.1 3.6 2.7 1.9 0.9 2.8 5.5 8.3 55

60 12.6 11.5 10.4 9.3 8.2 7.1 6.0 4.5 3.6 2.8 1.8 0.9 2.7 5.5 60

65 13.5 12.4 11.3 10.2 9.1 8.0 6.9 5.4 4.5 3.7 2.7 1.8 0.9 2.8 65

70 14.4 13.3 12.2 11.1 10.0 8.9 7.8 6.3 5.4 4.6 3.6 2.7 1.8 0.9 70

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

Target Speed

Acceleration / Deceleration Time (in second)

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LRV Speed Restrictions TableSpeed Curve Radius Without Cant Curve Radius With Cant

0 -- --

5 -- --

10 11 --

15 20 11.0

20 32 16.6

25 50 25.1

30 71 31.6

35 97 47.4

40 126 62.0

45 160 77.5

50 197 93.8

55 238 113.6

60 284 135.7

65 333 160.0

70 386 186.4

75 443 214.6

80 503 284.0

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Enhanced LRT Facilities

KCRC has installed a new LRT Signalling System for Tin Shui Wai Phase IV Extension in December 2003. It is scheduled to replace the existing LRT Signalling System in Tuen Mun, Yuen Long and Tin Shui Wai areas by end 2005 or early 2006.

The new LRT Signalling System has incorporated some new facilities to enhance the operation of the system.

Subject to the approval of TD, the Enhanced LRT facilities might be implemented along with the new Signialling System. If it happens, the future ATC System should take account of the Enhanced LRT facilities.

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Efficiency

• Latched / unlatched demand

• Compensation time

• Flexible all red facility

• Variable Dwell Time

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Latched/Unlatched Demand

Latched Demand- The demand remains active until the phase or stage is served.

Unlatched Demand– The demand is cleared if the demand condition ceases before the phase or stage is served.

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Compensation Time

If a VA phase is curtailed by LRV priority, an extension of the VA maximum time of that VA phase may be introduced next time when it gains right of way.

4 different sets of compensate timers can be configured in associated with the LRT phase to cope with the AM peak, PM peak, Off-peak and Fault Mode operations.

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Phase Compensation

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