1. Date:
Tool box talk
Shallow service
strikes – What
can you do?
Kier MG Limited
01/04/2013

2. You have achieved zero strikes
Many days there are no strikes, many weeks there are no strikes and
there have been months when no strikes have been reported. The
last time was December 2012!
So why do strikes happen?

3. Warning: Streetlights

4. Warning: Not always electric

5. But why?
 We find the majority of our service strikes are shallow and you
have already located them.
 We excuse these strikes due to their unknown depth and have
decided they are unavoidable, but we have enough evidence
across our business to show that these shallow services are not
unknown or unexpected anymore.
We must learn to expect shallow services
 During investigations carried out in to service strikes the teams
will often refer to removing the surface material as a different
process as digging below it.
It is not a different process
The digging starts from the very top

6. Reasons or excuses?
 “Yet again this service was moled in at an angle, gas services are
supposed to go in straight, the gas guys on site are digging one hole on
the main and Moling 2 or 3 services from here at angles and our guys
don’t stand a chance” - Manager
 “Team did a Cat & Genny scan of the area services picked & marked up.
They then broke the tarmac but the service was directly underneath. A
member from WPD was there & noted the cable depth was too shallow”.
- Manager
 ”The team had located the Cable but it was in the Tarmac, we do not know
the depth of the cables” - General Foreman
 “Cables and services can be at any depth” - Team
 “Streetlights are not powered in the daytime” - Team
 “Banksman saw service as slightly scraped it, no damage, slight pin hole.
Digging with mini digger” - General Foreman

7. How to overcome the problem...
 When you investigate the area to be dug look around and identify
any street furniture, road scars and other clues
 You will check the drawings, and with the CAT and Genny scan the
area using all modes
 You will have marked up the located services with spray paint,
wax crayon or chalk
 You will then plan to cut the surface, selecting the right tool for
the task
 You must not cut or break directly over the marked services, you
could either directly pierce it, cut it or push a section of the
surface in to the service below.
You have done the clever bit, don’t cut the service by
breaking or cutting over your own marks.

8. Choose and use tools carefully...
 A circular saw can cut up to 100mm depth, you can feel when you
have broken the surface layer. By plunging the saw in to full depth
you will hit the sub-base this will damage the blade and you will
find those shallow services
 Using a breaker over the marked services can drive the surface
layer into the shallow services even if you do not directly hit the
service itself
 Using hand tools; if you stab in to the ground with any hand tool
you can cause as much damage as using a powered breaker
 Whatever tools you choose to use you must think about the way
you use them:
 Don’t cut across the marking up
 Don’t stab the ground with hand tools.

9. YOU are the professionals
You provide a service to the community, where would we be with no
water, electricity or waste water disposal.
You don’t just dig holes!
Everyday you are working to the best of your ability to carry out the
task and overcome the problems you face.
And everyday you face the possibility of a strike so why some days
do you avoid the services.
What is different?
What can you do to work safely?

10. Know unknown’s!
Through our personal experiences and the corporate memory we
know to expect shallow services even if they are laid incorrectly.
“Reports that say that something hasn't happened are always interesting
to me, because as we know, there are known known's; there are things
we know we know. (shallow, poorly laid services)
We also know there are known unknowns; that is to say we know there
are some things we do not know. (shallow, poorly laid services)
But there are also unknown unknowns - the ones we don't know we don't
know” (shallow, poorly laid services)
D. Rumsfeld
“There is little excuse for damaging a service you have already
located”

11. Injury, cost and disruption...
BBC NEWS, Man hurt in city centre explosion
A man suffered serious injuries in an electrical explosion in central London
which led to a power cut. Shops were evacuated and witnesses heard a loud
noise and saw smoke in Hanover Street, south of Oxford Circus.
The man, in his 60s, is being treated for burns which are said to be life-
threatening, after he drilled through an electric cable. A cordon has been put
in place between Hanover Street and Regent Street but power has been
restored to the area.
Electrical Cable Cut - 12 December 2012
Fire-fighters were called to reports of a minor explosion, believed to have
been caused by a workman cutting through an electrical cable, on High
Holborn.
One man sustained burns and was taken to hospital by the London
Ambulance Service.

12. You work with these hazards everyday...
Joint failure
The explosion was caused by an electrical problem known as a "joint failure",
Central Networks power distribution company said. The joint is what connects
two sections of underground cable.
"The two pedestrians, a man and a woman, were treated at the scene for
burns to their arms, legs, faces and hair.
Faulty power cable
A central London resident has released video footage of the moment when a
pavement exploded in central London, narrowly missing a passer by.
The blast, which left a crater in the middle of the street, occurred at about
10:25 BST on Thursday and is believed to have been caused by a faulty
power cable.
Witness Charlie Brook, who filmed the second explosion from her window,
described hearing three explosions, the most dramatic being the second blast
which saw flames erupt into the air.

13. A damaged electric cable filmed in Pimlico, London