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Rail Capacity Workshop. A Primer on Capacity Principles New Technologies Public Sector Needs . SCORT/TRB Rail Capacity Workshop - Jacksonville Florida . SCORT/TRB Rail Capacity Workshop - Jacksonville Florida . 1. 1. Part 2:

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Rail capacity workshop

Rail Capacity Workshop

  • A Primer on Capacity Principles

  • New Technologies

  • Public Sector Needs

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

1

1


Rail capacity workshop

Part 2:

Conventional Signaling and Train Control Technologies- A Primer

  • Signal and train control functions

  • Train control and dispatching

  • Signal systems and equipment

  • Capacity effects

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

2


Signal and train control functions

Signal and Train Control Functions

  • Ensure Safety

    • Collision Prevention

    • Over speed prevention (some systems)

  • Train operations management

    • Set or authorize routes

    • Manage train priorities

Advanced train control systems supplement and enhance, but do not replace these functions

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida


Facilities and installations

Facilities and Installations

  • Central office

    • Dispatchers desks (work stations)

    • Remote switching (where available)

    • Track layout displays

    • Support software

  • Office to field communications (voice radio, “code line”)

  • Field installations

    • Wayside signals

    • Switches – powered and manual

    • Block systems

    • Track circuits

    • Interlockings – prevent conflicting signal and switch settings

    • Track-train communications (where applied)

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

4


Track capacity effects

Track Capacity Effects

  • Track capacity depends on the technical features of office and field systems, especially:

    • Block system types (manual, automatic, CTC)

    • Block lengths

    • Use of track circuits for train detection

    • Switch control – powered or manual

    • Train speeds – freight and passenger

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida


Manual block system mbs

Manual Block System (MBS)

Manual Generation of Authorities

Voice Transmission & Repeat (3-5 mins)

Voice Location Reporting & Authority Release

Manual Operation of Switches by Crew

Low Capacity Operation – e.g. branch lines

Dark Territory

Station A

Authority Limit

Station B

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

6

22 September 2010


Rail capacity workshop

MBS With Automatic Block System (ABS)

  • Similar to MBS, except

    • Automatic Signals Protect Rear of Train

      • Roll up of Authority

      • Automatic detection of train using track circuits

    • Higher Capacity Operation – applied to lower traffic main lines

Automatic Block Signals

Station B

Station A

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

7


Rail capacity workshop

Centralized Traffic Control

  • Consists of Signals & Switches operated by central dispatcher

  • Major advantage is avoiding manual switch delays

Remote Control

of Switches / Signals

Supervisory Office

Control and/or Indication

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

8


Rail capacity workshop

Centralized Traffic Control (cont)

  • Authority conveyed by Signal Indication

  • Track Circuits convey train location to dispatcher

  • Block system protects train in block

  • Much higher capacity

  • Better train performance

  • Applied to most higher capacity main lines on US freight network outside terminal areas

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

9


Rail capacity workshop

Braking Curves

– Mixed Freight and Passenger Traffic

  • Block length is a function of freight train braking

  • Typically 2 – 3 miles length

Higher Speed

Passenger

Speed

Loaded

Freight

Passenger

Or Commuter

Block Design Distance

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

10


Rail capacity workshop

Wayside Signal Spacing

Signal A4

Signal A3

Signal A2

Signal A1

Train 2

Train 1

Y

G

R

G

Block A1

Block A5

Block A3

Block A2

Block A4

Direction

of Travel

Block is occupied by train

No

Code

Normal Speed

Normal

Speed

Caution Speed

Zero Speed

Block length fixed by maximum speed, civil limits, grade, and worst train braking distance.

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

11


Rail capacity workshop

Signal Spacing - Options

Signal A1

Signal A5

Signal A4

Signal A3

Signal A2

Train 2

Train 1

G/R

Y/G

G/R

Y/R

R/R

Block A1

Block A2

Block A5

Block A3

Block A4

Block A6

Block is occupied by train

Normal

Speed

No

Code

Normal Speed

Advanced

Approach

Zero

Speed

Caution

Speed

Additional aspects provide finer control of train movement, at additional cost and complexity. Trains operating at different speed limits may require different rules.

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

12


Automatic systems

Automatic Systems

  • Most conventional systems rely on engineer compliance with signals and operating rules

  • Automated systems provide in cab displays and may enforce compliance

  • Principal systems are:

    • Automatic Train Stop – ATS

      • Enforce braking if engineer fails to respond to signals

      • Normally 8 second delay before enforcement

    • Automatic Cab Signals - ACS

    • Automatic Train Control – ATC

    • Civil Speed Enforcement – NEC and some NJT only

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida


Rail capacity workshop

Direction of Travel

Signal

Train

Driver’s Panel

Processor

Signal Data

Speedo

Code Transmission in Rails

Signal

Data

Data

Code

Brake

Interface

Code Pick-Up

Coils

Code

Generator

Cab Signals

  • Aspect transmitted display in engineer’s cab

  • Brakes apply automatically if authority is exceeded

  • Used on NEC, LIRR, MNCR, NJT, limited elsewhere

  • Two types:

    • Intermittent

    • Continuous

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

14

22 September 2010


Rail capacity workshop

No changes can occur while train

is outside of limited intervals.

Intermittent , ATS, ACS, ATC

  • Speed authorization is passed to train at limited

  • intervals, typically at signal locations.

  • Train stores information until next authorization is

  • received.

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

15


Rail capacity workshop

Continuous ATS, ACS, ATC

  • Speed authorization is continuously updated to

  • vehicle.

  • Changes in speed authority can be made at any

  • time, and are visible to operator immediately.

  • Capability to increase traffic; immediate recognition

  • of aspect upgrades allow quicker response.

  • Loss of signal is most restrictive, stopping train.

  • Train requires no ‘memory.’

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

16


Rail capacity workshop

Signal A4

Signal A3

Signal A2

Signal A1

Train 2

Train 1

Y

G

R

G

Y

Without ATP, Train 2 continues to slow throughout block, even though Train 1 proceeds past Signal A1.

Signal A4

Signal A3

Signal A2

Signal A1

Train 2

Train 1

Y

G

R

G

Y

G

With ATP, Train 2 can resume normal speed as soon as Train 1 proceeds completely past Signal A1, increasing capacity

Advantages of Continuous Automatic Systems

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

17


Rail capacity workshop

Intermediate Signals - Non-controlled signals other than distant signals –

Aspect display cascades from next signal aspect. Most restrictive

display is “Stop and Proceed.”

Distant Signal - Last automatic signal before

a home signal. Most restrictive display is

usually “Stop and proceed.”

Home Signal - Controls entrance into interlockings.

Most restrictive display is “STOP.”

Types of Signals

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

18


Rail capacity workshop

Types of Signal – Speed Signaling

  • Speed Signaling

    • Displays speed at this and next signal

    • Turnouts speeds displayed where applicable

    • Requires many signal aspects

    • Applied on the NEC

Signals indicate authorized speed:

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

19


Rail capacity workshop

Signal Systems – Route Signaling

  • Route Signaling

    • Displays 3 or 4 Aspects

      • Clear , (double Approach), Approach to Stop & Stop

      • Diverging route, where applicable

        • Turnout speed is shown in timetable

Signaling indicates selected route:

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

20


Rail capacity workshop

>20 Seconds

Highway Crossing Protection

Minimum warning time by state regulation or FRA is 20 seconds.

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

21


Rail capacity workshop

Highway Crossing Protection

20 seconds = 2933 feet at 100 MPH

80 seconds at 25 MPH

FixedTrack CircuitApproach - Varies with train speed

20 seconds = 733 feet at 25 MPH

20 seconds – Any Speed

Constant Warning- Grade Crossing Predictor

Measures train speed and adjusts warning for

constant warning time

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

22


Rail capacity workshop

Highway Crossing Protection

Highway traffic signal pre-emption at nearby intersections.

When train approaches, highway traffic signals prevent turns towards crossing , while allowing cars to clear crossing.

22 September 2010

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

23


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