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
• If you strip back the requirement for a road
tunnel to the basic level there are two real
requirements:
A Safe Tunnel; and
2. Available Tunnel
1.
• The hard and soft elements are key
contributors to meeting these two
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; and
2. Available Tunnel
• 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.
• 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
• 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
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.
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)
• 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)
• 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)
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 )
• 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.
• A comprehensive MOR document allows a
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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 subcontracts.
Give a good understanding of the resilience of
the tunnel.
Minimises the risk of tunnel closure.
 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; and
2. Available Tunnel
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

Time
New systems
Existing systems
Temporary Systems
Time
New systems
Existing systems
Temporary Systems
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.

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.
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
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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.
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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
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