Minimum stair width for carry-down evacuation

[Revol]

Is anyone aware of guidance regarding carrying wheelchairs down stairs and minimum widths?

The old SSLD 6 (Internal Stairs in Schools) for guidance on what width is required and this document states the following on page 19?.

? 1600mm. This enables two adults to pass each other with ease and permits 3 people to safely carry down a wheelchair user when required

In practice this would be very difficult to do and manage so isn't something I'm aware that fire safety design guidance considers. 

[AnthonyB]

This issue is filled by the industry that's emerged over the last 20+ years in providing evacuation aids that are single operator and narrow enough for most stairs and the presumption is that you would use these, have a managed lift use plan or make alternative service provision.

We all know there are going to be situations where none of these three are viable, but it seems to be the default!