“Balancing the hard and the soft elements”

Len Smith

Understanding the benefits of balancing the risks between the tunnel systems (the hard elements)  and the operational approach (the soft elements)   During Normal Operation During Refurbishment

“Balancing the hard and the soft elements”

• If you strip back the requirement for a road tunnel to the basic level there are two real requirements:

1. A Safe Tunnel; and2. Available Tunnel

• The hard and soft elements are key contributors to meeting these two requirements.

Basic Requirements

• Perhaps the last slide may be a statement of the obvious but these two fundamental points can often get lost/forgotten when embroiled in the detail of operations and particularly when involved in design and refurbishments.

• So first point – every so often stand back from what you are doing and ask does it increase or decrease the risk associated with meeting the two fundamental requirements?

1. A Safe Tunnel; and2. Available Tunnel

“Basic Requirements”

• Hard Elements are the physical systems and equipment in the tunnel such as:-

Power supplies CCTV IDS Lighting Signals Pollution Sensors Drainage Telephones

• When looking at the hard elements the criticality of the element and the redundancy in the provisions need to be taken into account.

Hard Elements

• Soft Elements are the procedures and people associated with the tunnel such as:-

Operational Procedures Maintenance Procedures Tunnel Control Room Staff Maintenance resources Traffic Officers etc

Soft Elements

• When looking at the soft elements examples of issues that need to be considered are:

Are maintenance staff available day and night or just day

Availability of specialist maintainers Tunnel control room or network control room Control room manned 24/7or only during the day On road traffic officers Closure availability Maintenance frequencies

Soft Elements (contin)

How can balancing the hard and soft elements help?

• During the life of a tunnel , or at various stages of a refurbishment, it is inevitable that the resilience of the hard elements will reduce.

• This can be due to a failure of part of a system or in the case of a refurbishment the introduction of a temporary system or use of a system that has not been fully tested and commissioned.

Balancing the Two

How can balancing the soft and hard elements help?• Example 1- Tunnel has overlapping CCTV Loss of 1 camera –not significant deal with at

next closure – inform operator. (Continue operation of tunnel - Green status)

Loss of 2 adjacent cameras- significant deal within next closure - alert operator and inform to use adjacent to clarify any potential incident- alert on road team to increase drive through. (Continue operation of tunnel - Amber status)

Balancing the Two

• Example 1 - Tunnel has overlapping CCTV (contin.)

Loss of all cameras- very significant deal within 24hrs – mobilise maintainer -alert operator - alert on road team to continuous drive through. (Continue operation of tunnel - Amber status)

Alternatively if the soft resource is not available for continuous drive through then the time to deal with would be reduced to say 2 hours and if not resolved a possible change to (Consider closing tunnel – Red status)

Balancing the Two

• Example 2 - Tunnel has 10 jet fans – 6 required for fire response

Loss of 1 jet fan- not significant deal with at next closure – inform operator. (Continue operation of tunnel - Green status)

Loss of 2 jet fans significant deal within 24hrs – mobilise maintainer -alert operator (Continue operation of tunnel - Amber status)

Loss of 4 jet fans very significant deal within 2hrs – mobilise maintainer -alert operator and fire service (Consider closing tunnel – Red status)

Balancing the Two

Example 2 (contin)- Alternative approach with increased soft provisions:Loss of 4 jet fans very significant deal

within 2hrs – mobilise maintainer -alert operator and fire service - Maintainer confirm local switching can be undertaken at plant room – maintenance staff available for continuous attendance (Continue operation of tunnel - Amber status Tunnel )

Balancing the Two

• The approach used in the two previous simple examples can be used for all the systems and operational procedures.

• For this approach to work it requires an in depth review of each system and their interactions.

• Once this has been done the Minimum Operating Requirements for each system and procedure can be draw up.

Minimum Operating Requirements

MOR - Example

• A comprehensive MOR document allows a considered approach to be taken in response to reduced provisions.

• Gives the operator clear guide lines on required mitigation measures.

• Helps prioritise maintenance response.• Sets response times for maintenance sub-

contracts.• Give a good understanding of the

resilience of the tunnel.• Minimises the risk of tunnel closure.

Benefits of MOR Document

Live tunnel refurbishment result in a progressive change from the exiting systems to the fully refurbished tunnel with new systems.

However the basic requirements still need to be met at all stages:-

1. A Safe Tunnel; and2. Available Tunnel

Live Tunnel Refurbishment

During the various stages of a live tunnel refurbishment the system configurations will progressively changes e.g. introduction of temporary system and/or partly completed systems.

This inherently means that the resilience and integrity of the systems is reduced or at least not fully tested and commissioned.

The following diagrams illustrate this

Tunnel Refurbishment

New systems

Existing systems

Refurbishment Systems Time Line

Temporary Systems

Time

New systems

Existing systems

Refurbishment Systems 1st Bore Time Line

Temporary Systems

Time

The second diagram illustrates the typical situation at the end of the completion of the first bore.

The situation is similar for a single bore tunnel at the end of each night closure when reopening to traffic.

The Tunnel Manager/Operator has to be confident that the tunnel is safe to open to traffic.

Tunnel Refurbishment

How can this confidence be given?By:-

Understanding the resilience of the hard systems as the works progress.

Identify the hard systems high risk areas.Review the soft systems currently in place.Enhance the soft systems to compensate for

the hard systems high risks.

Tunnel Refurbishment

What does this mean in real terms?In effect it is producing a high level MOR.Typical soft system enhancements use on

tunnel projects include:• 24hrs dedicated tunnel monitoring• Enhanced maintenance • Increased inspections• 24hr on site maintenance attendance for key

systems e.g. scada• Holding key spares for both new and temporary

systems• Enhanced operational procedures• Modified emergency plan

Tunnel Refurbishment

What benefits has this shown in the real world?• An example was the M25 DBFO- A1M

Hatfield tunnel refurbishment.The first bore programme delays were

recovered to allow opened ahead of the revised programme date.

Power system migration was helped by utilising a generator supply.

The tunnel was fully opened to meet a key additional DBFO finance release.

The tunnel was fully opened to traffic without speed restrictions.

Tunnel Refurbishment

Balancing the Soft and Hard Elements to provide :• A Safe Tunnel; and• Available Tunnel.

Developing Minimum Operating Requirements based the above approach gives clear understanding of the tunnel resilience and reduces the risk of tunnel closures.

Can have significant benefits when undertaking tunnel refurbishments

Summary

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