MAR/General/TBT-MAR-017

Tidal Working Window Procedures

Marine & Coastal WorksGeneralTidal Working Window Procedures

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Tidal Working Window Procedures

TBT-MAR-017

Marine and coastal construction work is often restricted to tidal windows when the tide is low enough to expose the work area. Operatives must complete their tasks and evacuate before the rising tide floods the work zone. Misjudging the tidal window or failing to monitor water levels has led to workers becoming trapped, stranded, or drowned. This talk covers the procedures for safe working within tidal windows.

Key Hazards
Drowning from being trapped by a rising tide in the work area
Equipment and plant stranded by rapidly incoming tidal water
Hypothermia from unexpected immersion in cold tidal water
Slips and falls on wet, seaweed-covered surfaces at low tide
Control Measures
  • Calculate the safe working window from published tide tables with an appropriate safety margin.
  • Brief all operatives on the start and finish time of the tidal window before each shift.
  • Appoint a dedicated tide watcher to monitor water levels and give early warning of the rising tide.
  • Set a mandatory withdrawal time that allows sufficient margin for safe evacuation of all personnel.
  • Establish and clearly mark the escape route from the tidal work area to high ground.
  • Ensure all workers near tidal water wear personal flotation devices throughout the shift.
  • Remove all plant, equipment, and materials from the tidal zone before the tide returns.
  • Carry out a head count when all personnel have withdrawn from the tidal work area.
  • Never extend the working window beyond the agreed time regardless of work pressure.
Emergency / Rescue

If anyone becomes trapped by the rising tide, call 999 and request the Coastguard immediately. Do not attempt a rescue in tidal water unless trained and equipped. Throw a lifebuoy if the person is within range. Account for all personnel at the muster point.

Remember
  • Never extend the tidal working window beyond the agreed safe time under any circumstances
  • A dedicated tide watcher must monitor water levels and give early warning throughout
  • Know the escape route from the tidal zone to high ground before starting work
  • Wear a personal flotation device at all times when working in the tidal zone
  • Carry out a head count when all personnel have withdrawn to confirm everyone is safe
Applicable Legislation: CDM 2015 · Health and Safety at Work etc. Act 1974 · MHSWR 1999 · Merchant Shipping and Fishing Vessels Regulations
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