Application of health and safety law to "walk to work" vessels

  • Operations notice: 80 (version 2)
  • Issue date:  February 2014


Walk to work [W2W] guidance is re-issued to:

  • Re-affirm HSE's view that W2W vessels used to transport and accommodate workers, but which do not remain at an installation for a period longer than that required to transfer workers, are not offshore installations as defined by the Offshore Installations and Pipeline Works (Management and Administration) Regulations 1995 (MAR) and do not require safety cases.
  • Clarify for duty-holders that they may need to revise their safety cases with respect to the W2W activity.
  • Inform duty-holders that if they plan for a vessel to remain stationed for a period longer than that required to transfer workers, the vessel will become an installation under the definition in MAR and require a non-production safety case.


Revision of the installation safety case

Where W2W activity 'in connection with' is not described in the installation safety case and/or materially changes the basis on which the current safety case was accepted, duty-holders should submit a revision under the Offshore Installations (Safety Case) Regulations, regulation 14(2). The revision will need to consider the adequacy of the major hazard control arrangements, including emergency response and evacuation arrangements.

Preparation of a non-production safety case

If a vessel is to remain stationed alongside an installation for a period longer than that required to transfer workers, it will in HSE's view attract the status of an offshore installation. Therefore, the owner of the vessel will have to prepare a safety case and have it assessed by HSE.  A walk to work vessel with an accepted Safety Case may be more versatile in providing a service to the offshore industry.

HSE's legal opinion

HSE's view is that although a W2W vessel used to provide accommodation and possibly transport, but which does not remain at an installation for a period longer than that required to transfer workers, the length of time a vessel spends at an installation and its itinerant nature means that it does not have a sufficient degree of permanence to be considered as 'standing or stationed'. It therefore does not become an offshore installation as defined by MAR and therefore does not require a safety case.

The activity of transferring workers on and off an installation is as an 'activity in connection with' the installation. As such, the Health and Safety at Work etc. Act 1974 (HSWA), and certain regulations made under the Act, will apply to the activity by virtue of the Health and Safety at Work Act 1974 (Application Outside Great Britain) Order 2013 (AOGBO). HSWA will also apply to the activity of providing accommodation for the workers.

When providing accommodation for workers, out with the short periods taken to transfer them to and from an installation, duty-holders should ensure that W2W vessels are located far enough from the installation so that they are not affected by any dangerous event that may take place on the installation. Typically, where possible, this will be at least 500 metres from the installation.


For several years, duty holders have used W2W vessels for the purposes of transporting and/or accommodating workers. The traditional W2W arrangement involved the vessel remaining stationed whilst the workforce is transferred to the installation and then moving to a safe distance. More recently, there have been further proposals to extend their use to facilitate a need for increased maintenance and repair on offshore installations. 


If workers are transported and accommodated offshore by W2W vessels, this is by definition a marine activity, as well as being an activity in connection with the offshore installation. HSE will, therefore, liaise closely with the marine authorities over any jurisdiction. These arrangements are covered under the Memorandum of Understanding between the Health and Safety Executive, the Maritime and Coastguard Agency and the Marine Accident Investigation Branch for health and safety enforcement activities etc. at the water margin and offshore memorandum with MCA and MAIB.

HSE is aware that the MCA has engaged the offshore industry over W2W vessel design standards and operation.

Updated 2021-02-16