tunnel cooling programme (tcp) systems engineering · tunnel cooling programme (tcp) systems...

UNDERGROUND Engineering Directorate

Tunnel Cooling Programme (TCP)Systems Engineering

Mark Gilbey &

Jonathan Harding


Purpose

• Explain the complexity of the problem

• Explain how we are using Systems Engineeringin the Tunnel Cooling Programme to manage thenetwork wide, long term cooling challenge

• Show examples of the proposed solutions


Problem• The TCP was set up in recognition of LU’s desire to

improve the thermal conditions for the travelling public.

• Whilst thermal conditions on some portions of LU’sunderground system are already reported to beuncomfortable, conditions could become significantlyworse as a consequence of the proposedimprovements in journey time capability required aspart of the PPP contracts.

• The TCP GOAL is to improve passenger comfort andsafety by maintaining 29°C station temperatures intime for the line upgrade programme between 2012and 2019.


Current Tunnel Temperatures


Energy Sources


79%

11%

10%

Tunnel Walls

Piston Effect

Mechanical

Ventilation

System Heat Sink67TS / 28TPH


CAR AIR VOLUMETUNNEL AIR VOLUME

CAR WALLS

CARINTAKE

AIR

CARRELIEF AIR

PASSENGERS

INTERNALAUXILIARIES

EXTERNALAUXILIARIES

TUNNEL WALLS

RESISTORGRIDS

INTAKE AIRFROM

UPSTREAMSEGMENT

CAR HEAT BALANCE

TUNNEL HEAT BALANCE

AC SYSTEMAC

CONDENSER

skin

fat

muscle

core

radiant flux

HVAC inlet

Person

Train

Mesh

Cross Section

POSSIBLE PARAMETERSRelative humidity inside and outside the trainAir temperature inside and outside the trainCarbon dioxide inside and outside the trainWall temperature inside and outside train

In-carriage air movementCondensation

Solar radiation outside of tunnelsWind outside of tunnels

Carriage ventilationTunnel ventilation

Heat dissipation from equipment inside trainsHeat dissipation from equipment outside trains

Sustained electrical powerPosture

AgeWeight

Train loadingCrowding

Psychological stressPre-exposure

Acclimatisation

STRAIN INDICESPassenger core temperature

Rate of dehydrationMaximum exposure to carbon

dioxideHeat Stress Index

STRESS INDICESEnvironmental indices such as:

Effective TemperatureWet Bulb Globe Temperature

Oxford Index

ALLOWABLEEXPOSURE TIMEOR


How the Tunnel Cooling Programme is usingSystems Engineering


TCP Document hierarchy

SteeringGroup brief

Technical Work scope packages

Design and BuildPackages

Detailed design

Project ObjectiveDefinition

FunctionalSpecification

Operational RailwaySystem Specification

Principal RequirementsSpecification

Line Application Specification


Complexity of problem• 98 delivery projects

• Indirect interfaces between projects (TCP and other)

• Working on an existing operational railway

• Using and upgrading old assets that are not normally used

• Limited space availability

• Limited engineering hours

• Not safety critical (less defined target requirements)

• Lots of unknowns

• Lots of Stakeholders

• Some potential solutions never used before in this environment


Solution breakdown


Systems Engineering Approaches to be usedby TCP

• Functional Failure Analysis

• High level RAMS apportionment

• Do nothing QRA

• V lifecycle

• FRACAS

• Change Control & Stakeholder consultation

• Requirements Management using DOORS

• RAMS Models

• Training and maintenance needs assessment


Failure mode <3hr >3hrs

100% failure single station low tangible

50% failure multiple stations low tangible

100% failure multiple stations tangible high

Functional Failure analysis results


RAMS targets

Using the assumptions that;

• 29°C or below is the targettunnel cooling temperature;

• Upper limit is undesirable;and

• SES modelling shows howlong it takes for thetemperature to raise 3°C tothe upper limit on 100%failure of a cooling solutionand so dictates reactiontimes;


Do nothing QRA.

• Purpose – to calculate the change to the LU customer riskprofile if we did nothing, to set the baseline case.

• The definition of “do nothing” in this scenario is that notunnel cooling is undertaken and the current plans for theupgrade of the underground go ahead including:

– More trains per hour (peak and off peak), leading to lesscoasting and more acceleration and braking.

– Upgrade to Rolling stock.

– Upgrade to stations.


Engineering Lifecycle from SEMP

Note: there will be 1 high level V lifecycle and lots ofsmaller solution specific V lifecycles

At a high level the business requirement is;

•“deliver the means to reduce the LU network heat load by theimplementation of a set of feasible solutions which can bedelivered at a reasonable price and in an appropriate timescale.”

•The TCP GOAL is to improve passenger comfort and safety bymaintaining 29°C station temperatures in time for the line upgradeprogramme between 2012 and 2019.


Lifecycle definition phase example (2+3)


FRACAS Process and aims

AIMS

• Establish a database of all the products.

• Monitor the Reliability, Availability, Maintainability and Safety metrics of the newequipment to compare actual against predicted performance.

• Develop an agreed approach to identify corrective actions and monitor their success.

• Improve the understanding and reliability of the new assets being installed by TCP.

• To provide evidence that the equipment installed is operating safety and reliably.

Ope

ration

al

railw

ay

Failure OccursFailure

recorded inSST-A

Ma

inta

ine

rFault repaired

and fault and fixdata entered

SST-A

TC

PF

RA

CA

Ste

am

PopulateFRACAS

database withasset specificinformation

Update FRACASdatabase withrelevant failure

and fix informationfrom LU database

Analysefailuredata

FR

G FRG reviewanalysisreport

Doesassetmeet

RAMStargets?

Correctiveaction (CA)

recommended

Implement and MonitorCA to determine

effectivenessNo

Produce regular RAMSreports and feed into

lessons learntdocumentation

Yes

Ope

ration

al

railw

ay

Failure OccursFailure

recorded inSST-A

Ma

inta

ine

rFault repaired

and fault and fixdata entered

SST-A

TC

PF

RA

CA

Ste

am

PopulateFRACAS

database withasset specificinformation

Update FRACASdatabase withrelevant failure

and fix informationfrom LU database

Analysefailuredata

FR

G FRG reviewanalysisreport

Doesassetmeet

RAMStargets?

Correctiveaction (CA)

recommended

Implement and MonitorCA to determine

effectivenessNo

Produce regular RAMSreports and feed into

lessons learntdocumentation

Yes

UNDERGROUND Engineering DirectorateStakeholder consultation

Stakeholder Organisation

London Fire andEmergency

Planning Authority

LU Safety Qualityand Environmental

Department

LU EngineeringDirectorate

Tube Lines (JNP)

Metronet (BCV)

Metronet (SSL)

Thames Water

Environment Agency

Station UpgradeTeams

Step free Access

Programs Tunnel CoolingProject

Transportfor London

Infracos

LU ChiefProgrammes office

TransportTrading Ltd

LondonUnderground

HSE

Mayors Office

RSSB

Customers

3rd Party

Housing associations

DFT

Highways

3rd Party utility suppliers

Other railways

Heritage Trust

Workforce

Research Groups

Local Authorities


Proposed solutions

Passive and active Measures

• Passive measures - reduce energy usage and hence heatdissipation on the underground:

• Wayside resistors.

• Capacitors on trains.

• Train operations and train planning activities.

• Regenerative braking.


Fan Coil Units

Borehole solution

3m

2m wide,approx 30kWcapacity

Platformobstruction isunlikely to beacceptable

Above head maybe the onlyalternative, butimpacts stationservices

Air Handling Units

Train

Tunnel

Cables

100mm diapipe with150mm longfins (typ)

Station Station

Station Station

Pipes in tunnels


Chillers

Blue Fans trial

Evaporative cooling

Draught Relief(about 10m² per shaft)

Under Platform Exhaust(about 70m³/s per station)

Draught Relief and Fan Operations(about 125 to 150m³/s per station end)

Ventilation shafts and underplatform exhaust

OPTION 1 – PAD TYPE

FACE VELOCITY LOW BUT MOISTURECARRY OVER LITTLE.

CAN WE GET UNITS WITH FACEVELOCITIES UP TO 5 m/s

OPTION 2 – SPRAY TYPE FACE VELOCITY HIGHER BUT MORE

MAINTENANCE. CAN WE RUGGED DRIFT ELIMINATORS

WITH VERY LOW MOISTURE CARRYOVER

OPTION 3 – TUNNEL SPRAY TYPE BETTER YEAR-ROUND

PERFORMANCE BUTMAINTENANCE ANDTECHNICAL CONCERNS.

CAN WE NOZZLES TO SPRAYAT SUB 100 MICRONDROPLET SIZE Under Platform Exhaust


Summary• Explained the complexity of the problem

• Explained how we are using Systems Engineeringin the Tunnel Cooling Programme to manage thenetwork wide, long term cooling challenge

• Showed examples of the proposed solutions


Any Questions?

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