www.hsl. gov.uk An Agency of the Health and Safety Executive
www.hsl. gov.uk An Agency of the Health and Safety Executive Tower
Crane Incidents Worldwide Ian Simpson Principal Specialist
Inspector, HSE Slide 2 An Agency of the Health and Safety Executive
OBJECTIVES To identify worldwide Tower Crane accidents 1989 to 2009
Obtain where possible the cause(s) of each accident identified Use
the information to advise/guide the UK Tower Crane industry to help
improve safety Slide 3 An Agency of the Health and Safety Executive
CRANE TYPES Confined to tower cranes commonly found on UK
construction sites. Only major accidents resulting in the collapse
of the crane considered Does not include Mobile Cranes Self
Erecting Tower Cranes Tracked Crawler Cranes Dockyard Cranes Gantry
Cranes & Container Cranes Slide 4 An Agency of the Health and
Safety Executive CRANE TYPES LUFFING JIB CRANE CONVENTIONAL TOWER
CRANE Slide 5 An Agency of the Health and Safety Executive Internet
Websites of trade/industry magazines craneaccidents.com &
towercraneaccidents.blogspot.com Websites of private individuals
with some connection with the industry (both U.S. based) Websites
of media local to the accident e.g. New York Times SOURCES OF
INFORMATION Slide 6 An Agency of the Health and Safety Executive No
single source of accurate information identified Trade websites
tend to be Ok for the initial report & will follow up with
further detail when available The two private websites often
inconsistent with the trade websites and are prone to (usually well
meaning) speculation. LIMITATIONS/DIFFICULTIES Slide 7 An Agency of
the Health and Safety Executive Not all the websites have knowledge
of all the accidents. Some accidents are given on one website but
not another. Local media usually reports in the immediate aftermath
of the incident and details can be vague & inaccurate
Geographic locations. Remote countries with less developed health
& safety cultures tend not to be as well reported (investigated
?) as U.S.A. & Europe LIMITATIONS/DIFFICULTIES Slide 8 An
Agency of the Health and Safety Executive LIMITATIONS/DIFFICULTIES
This can be frustrating Zibo City, China Battersea Visually similar
accidents. Top of the crane has parted from the mast section at the
slewing ring joint. Lack of detailed information from the China
accident prevents accurate comparison Slide 9 An Agency of the
Health and Safety Executive 54 accidents resulting in the collapse
of the tower crane involved identified since 1999. Information
prior to 1999 very scarce RESULTS Slide 10 An Agency of the Health
and Safety Executive These split into the following categories:
Erection/Dismantling or Extending (climbing) the crane Strong Winds
or Extreme Weather Foundation Problems Mechanical Issues (including
safety & control systems) Misuse of the Crane, e.g Overload,
Collision etc No details verified in the research to explain the
collapse RESULTS Slide 11 An Agency of the Health and Safety
Executive RESULTS 54 TOTAL Slide 12 An Agency of the Health and
Safety Executive EXAMPLES OF ACCIDENTS Erection/Dismantling or
Extending New York March 2008 Slide 13 An Agency of the Health and
Safety Executive EXAMPLES OF ACCIDENTS Erection/Dismantling or
Extending New York March 2008 Slide 14 An Agency of the Health and
Safety Executive EXAMPLES OF ACCIDENTS Erection/Dismantling or
Extending New York March 2008 Cause of accident focused on the
number and condition of the lifting slings used to lift/support the
tie in collar Four slings were used instead of eight recommended by
the manufacturer. Old slings were apparently used with no prior
inspection despite four new slings being offered by the
construction manager to the rigging crew Sling protection not used
Slide 15 An Agency of the Health and Safety Executive EXAMPLES OF
ACCIDENTS Erection/Dismantling or Extending New York March 2008
DAMAGED/FAILED SLING TIE IN COLLARS Slide 16 An Agency of the
Health and Safety Executive EXAMPLES OF ACCIDENTS
Erection/Dismantling or Extending New York March 2008 Nothing
technically wrong with the crane itself Accident centred on
competence, procedural, communication issues & condition of
lifting equipment in use These factors not confined to Tower Cranes
or foreign countries Slide 17 An Agency of the Health and Safety
Executive EXAMPLES OF ACCIDENTS Foundation Issues Seattle November
2006 Slide 18 An Agency of the Health and Safety Executive EXAMPLES
OF ACCIDENTS Foundation Issues Seattle November 2006 Crane mast
section severed approximately 15 feet from the base The foundation
was an uncommon design consisting of steel I section cross beams
supported by four concrete pillars Site workers raised issues
concerning the crane before the accident. They reported that the
foundation creaked & groaned far more than usual. Slide 19 An
Agency of the Health and Safety Executive Foundation Issues Seattle
November 2006 Photographs of the crane taken before the accident
show that the crane appeared to be leaning Accident attributed to
failure of welded/bolted joints in the foundation steelwork This
resulted in the crane leaning and overstressing the bottom of the
mast section EXAMPLES OF ACCIDENTS Slide 20 An Agency of the Health
and Safety Executive EXAMPLES OF ACCIDENTS Foundation Issues
Seattle November 2006 Slide 21 An Agency of the Health and Safety
Executive EXAMPLES OF ACCIDENTS Foundation Issues Seattle November
2006 Accident centred on design & manufacturing issues of the
foundation itself and communication issues Had the concerns raised
by the site workers been acted on could the accident have been
avoided ? Again, these issues not unique to the tower crane
industry or foreign countries Slide 22 An Agency of the Health and
Safety Executive EXAMPLES OF ACCIDENTS Foundation Issues Singapore
February 2008 PIN GROUND ANCHOR ATTACHED TO CONCRETE FOUNDATION
BLOCK MAST SECTION LEG More conventional foundation arrangement. No
accurate details concerning the root cause. It appears as if the
ground anchors have failed and the pins have pulled through them.
Slide 23 An Agency of the Health and Safety Executive EXAMPLES OF
ACCIDENTS Mechanical Issues New York May 2008 Slide 24 An Agency of
the Health and Safety Executive EXAMPLES OF ACCIDENTS Mechanical
Issues New York May 2008 Crane involved was a Kodiak at least 24
years old Production of Kodiak cranes ceased prior to the accident
Investigation showed that the accident was due to failure of a
welded repair to the slewing ring support structure at the top of
the mast section. Slide 25 An Agency of the Health and Safety
Executive EXAMPLES OF ACCIDENTS Mechanical Issues New York May 2008
Accident raised issues of use & maintenance of aged plant:- Why
did the slewing ring support structure require repairing in the
first place ? Who technically evaluated/authorised the welded
repair technique and inspection criteria/standards (if any) ? Was
the repair carried out to the required standards ? These sort of
issues not confined to the tower crane industry or foreign
countries Slide 26 An Agency of the Health and Safety Executive
EXAMPLES OF ACCIDENTS Mechanical Issues (Control System) Rotterdam
July 2008 Slide 27 An Agency of the Health and Safety Executive
EXAMPLES OF ACCIDENTS Mechanical Issues (Control System) Rotterdam
July 2008 The crane was lifting a heavy load within its rated
capacity close to the mast. It was required to slew the crane &
manoeuvre the load along the jib such that the load was very close
to the maximum permitted at the required radius During final
positioning of the load it ran away down the jib, overloading the
crane and causing it to fail at the mast section Slide 28 An Agency
of the Health and Safety Executive EXAMPLES OF ACCIDENTS Mechanical
Issues (Control System) Rotterdam July 2008 Prior to the accident
the hook block saddle was stationary in position along the jib and
under control of the mechanical saddle travel motor brake Slide 29
An Agency of the Health and Safety Executive Mechanical Issues
(Control System) Rotterdam July 2008 Under these conditions the
crane was leaning forwards The crane controls were operated to
bring the load in towards the mast section for final positioning of
the load Instead of moving towards the mast the load ran away to
the outer end of the jib EXAMPLES OF ACCIDENTS Slide 30 An Agency
of the Health and Safety Executive EXAMPLES OF ACCIDENTS Mechanical
Issues (Control System) Rotterdam July 2008 The hook block saddle
travel motor control system was a sophisticated modern PLC/Inverter
electronic system The accident was attributed to settings of the
control system When the controls were operated the hook block
saddle travel motor mechanical brake was released (solenoid
operated) before the electric motor had built up sufficient current
to hold the load against the downward slope of the crane jib Slide
31 An Agency of the Health and Safety Executive EXAMPLES OF
ACCIDENTS Mechanical Issues (Control System) Rotterdam July 2008
Since the crane was leaning forwards, the hook block and load
started to move towards the outer end of the jib The electric
braking of the motor was not sufficient to stop the load once it
had gathered momentum The mast section suffered structural failure
close to the edge of the building Slide 32 An Agency of the Health
and Safety Executive EXAMPLES OF ACCIDENTS Mechanical Issues
(Control System) Rotterdam July 2008 Slide 33 An Agency of the
Health and Safety Executive EXAMPLES OF ACCIDENTS Extreme Weather
Utrecht, Holland January 2007 Katowice, Poland January 2007
Liverpool, UK January 2007 Utrecht Liverpool Slide 34 An Agency of
the Health and Safety Executive EXAMPLES OF ACCIDENTS Extreme
Weather Speaks for itself really, no firm details concerning the
Utrecht & Katowice accidents other than the Katowice crane
reportedly literally snapped in half Common issues associated with
high winds (above 72 km/hr, 20 m/s) can include: The jibs of
luffing cranes being blown backwards Structural failure of jibs,
counter jibs and mast sections Prevention of the cranes ability to
free slew or weathervane Slew brake left on Advertising boards
along the jib and counter jib acting as sails Slide 35 An Agency of
the Health and Safety Executive SUMMARY Causes of tower crane
accidents in other countries have common recurring themes with the
UK and other industry sectors and include (in no particular order)
Poor design Improper or not sufficiently thorough
maintenance/inspections Inappropriate modifications or repairs and
failure to implement these to sufficiently high standards Human
Factors Training/Competency Miscommunication/Misunderstandings
Failure to follow procedures (shortcuts) Failure to act if
something is not right
