06072CaldwellIRSE-final

TMG

Generation of Optimised Automatic Signalling Layouts with Computer SimulationsDavid CaldwellIRSE Technical Conference, Sydney21st July 2006

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WorleyParsons TMG

resources & energyWhat is signalling trying to achieve?

“To consider railway signalling and telecommunications specifically, shouldn’t we focus on selling capacity? Indeed, safety alone does not really pay. Saying then ‘Signalling is safety for more trains’ is probably wrong. Signalling is a business tool…”

- Jacques Pore, IRSE President (March 2006 IRJ)

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WorleyParsons TMG

resources & energyIn more general terms

The system has to be inherently safe

We want to meet operational capacity requirements as

efficiently as possible

Target signalling capital to provide desired performance

along a line

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WorleyParsons TMG

resources & energyAutomatic Block Signalling

Broadest application is to Multiple Aspect Signalling

Also applied through fixed-block cab signalling

Core requirement for availability of braking distance are

the same in both speed and route signalling

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WorleyParsons TMG

resources & energyFor automatic signal layouts we want…

Signals placed safely in accordance with train braking

performance

Signal placement and spacing to be optimised for the

traffic requirements of the line

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WorleyParsons TMG

resources & energyFunctional Relationships

Capacity

Capacity

Braking distancesBraking

distances

Sighting

Sighting

Number of aspects

Number of aspects

HeadwayHeadway

Train speedsTrain

speeds

GradesGrades Rolling stock(Train Mix &

Performance)

Rolling stock(Train Mix &

Performance)

Speed limits

Speed limits

Signal spacingSignal

spacing

Dwell time or junction

delay

Dwell time or junction

delay

Time to clear

Time to clear

Overlap

Overlap

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WorleyParsons TMG

resources & energyLayout Aim

Layout optimised to

Either maximise line capacity with certain traffic

requirements

Or meet certain traffic requirements less than line

capacity

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WorleyParsons TMG

resources & energyLayout Aim

Very laborious to optimise a layout by manual

techniques, particularly under diverse traffic conditions

involves inaccurate generalisations

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WorleyParsons TMG

resources & energySimulation tools

Computer simulations make it possible to analyse the

observable characteristics of a railway system without it

existing in reality

SIMULATOR

ROLLING STOCK

TRACK

SERVICES

SIGNALLING

SPEED

BRAKING DISTANCE

CLEARANCE TIME

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WorleyParsons TMG

resources & energySimulation tools

Provides speeds to indicate whether a train can reach line speed at all, and whether short fast trains present more of a problem than long slow ones

Provides the necessary data to determine clearance times at any signal, and therefore provides achievable headway

Assesses braking distances on the actual (varying) gradients of the line, rather than on some fixed generalised grade applied to the whole block

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WorleyParsons TMG

resources & energySimulation tools

>Service braking distance

What is the gradient in this section?

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WorleyParsons TMG

resources & energySetting goals

In order to apply simulations to signal design, some

clear goals have to be set

Actual planned traffic diversity (dwell times, tractive

effort, length, braking rate)

Desired headway

Required braking conditions

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WorleyParsons TMG

resources & energyMethodical Approach

Methodical approach is required to maintain the integrity

of data

Must take care to select correct data for each

application- make sure data is “fit for purpose”

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WorleyParsons TMG

resources & energyCalibration

Usually braking distances for signalling the layout are

stipulated in design Standards or Principles

Simulations calculating braking distances must be

calibrated to the design standard

This is achieved by adjusting equipment delay times and

deceleration in different speed bands

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WorleyParsons TMG

resources & energyCalibration

Emergency Braking Distance GE52A

0

10

20

30

40

50

60

70

80

90

100

110

120

Distance [m]

Sp

eed

[km

/h]

GE52A Level

Level

GE52A F1:30

Falling30

GE52A R1:40

Rising40

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WorleyParsons TMG

resources & energyBraking Distance Simulations

Worst case brake service and emergency braking

curves for each train type

Non-stopping trains running at full free-speed

No Temporary Speed Restrictions

Unladen trains (maximum acceleration)

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WorleyParsons TMG

resources & energyHeadway Simulations

Apply normal in-traffic service-braking rates applicable

to each train

Apply all operational delays, such as stops, junction

delay, dwell time and recovery time

Apply all temporary speed restrictions that are

applicable in operation

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WorleyParsons TMG

resources & energyOptimising the Layout

Braking Distance

Distance (chainage)

Time

Train

Cle

ara

nce

tim

e “

A”

Signal A

Simulated service braking distance

Clearance point A

Overlap A

From clearance time and headway simulation

From Braking distance simulations

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WorleyParsons TMG

resources & energyOptimising the LayoutOptimise MAS

layout

Generate emergency braking distance along the route

Develop maximum density three aspect layout

Generate service braking distance along the route

Simulate clearance times

Develop maximum density four aspect layout

Are user requirements

met?

Yes

No

Are user requirements

met?No

Simulate clearance times

Yes

Test reductions in speed limits, or tolerability of

restrictive signal running

Produce signal locations and clearing point locations

Signal spacing and overlap requirements

Remove excess signals and

redistribute for consistent clearance

time

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WorleyParsons TMG

resources & energyHandling the data

Lots of data flowing between steps in the process

Results from different simulations have to be

consolidated

Data has to be handled simultaneously so that signal

placements are on the basis of clearing time, but are

always compliant with braking distance requirements.

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WorleyParsons TMG

resources & energyExpectations have changed

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WorleyParsons TMG

resources & energyThe information is in there…

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WorleyParsons TMG

resources & energyIRSE “Green Book” No27 headway

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WorleyParsons TMG

resources & energyWhich looks like this

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WorleyParsons TMG

resources & energyIt all needs to be tied together

Can do this in Excel

Requires some tricky macros and big formulae

Still requires manual execution of simulation and lots of data handling (means lots of checking)

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WorleyParsons TMG

resources & energyA specific interface

RAIL//SIG - Qld_test_layout1

File Edit View Insert Settings Window Help

Signal edit mode

System Rules: Brisbane Metropolitan 1.00

Service Braking: Longest of selected:

Brisbane suburban EMU

QR Superfreighter

Tilt Train (DMU)

Brisbane suburban SMU

Overlap: Longest of selected:

Fixed minimum 200m

Tilt Train (DMU)

Not loaded

Base file: mstest1.RAW

Clearance time: Greatest of selected:

Brisbane suburban EMU

QR superfreighter

Tilt Train (DMU)

Brisbane suburban SMU

Track gradient and features

Signal clearance timeClearance time simulation settings

Line speed

Free speed of train-type applied for headway analysis

Service braking distance

Service braking settings

Signal showing all displayable colours

That signal’s clearing pointEmergency braking distance

Overlap settings

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WorleyParsons TMG

resources & energySignal design robot?

Methodical application of simulations does provide an

efficient means of “roughing out” and making changes

This is not the complete story

External factors, such as sighting distance and forcing

signals to coincide on parallel lines

Case by case risk analyses

Still requires a skilled practitioner

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WorleyParsons TMG

resources & energyConclusion

Signal layouts can be optimised with the aid of computer

simulations

Optimisation means not only tailoring the layout to the

specific traffic requirement, but also having no more

signals that are required to meet that requirement

Applying simulations requires a methodical approach,

which has scope for much greater automation

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WorleyParsons TMG

resources & energyConclusion

Clear presentation of decision support information, such

as limits of signal spacing, overlaps and clearance

times, empower the user to make better decisions

Time and cost of development can be reduced,

infrastructure in the field can be better targeted

Design issues can be more quickly identified and

assessed in large projects

Thank you