Just one in five trains will run so the advice is once again only travel if you have to. Other workers - including traffic officers who work in the aftermath of road accidents - are walking out for the first time.

However, if you were planning a pre-Christmas getaway from Heathrow Airport, you'll be pleased to know that a planned strike by baggage handlers has just been cancelled.

This is my latest strike briefing, with lots of useful information on what is happening - and how it might affect you.

So what is Friday looking like?

Train delays again

Members of the UK's biggest rail union the RMT will walk out from midnight for 48 hours until the end of Saturday, hitting services throughout England, Scotland and Wales.

If you must travel:

*  Make sure you check with your rail operator before setting out to see which trains are running

*  Be prepared for no services at all on some routes

*  Be prepared for no early morning or late night services on other routes

*  Expect busy carriages with only one in five services operating between 07:30 - 18:30 GMT

The union is also planning further action over Christmas and in the New Year.

On the roads

National Highways traffic officers in the Public and Commercial Services Union (PCS) working in north-west England, north-east England, and Yorkshire and the Humber will stop work for 48 hours.

National Highways says no roads will be closed and it has "well-rehearsed resilience plans in place". About 125 out of 1,500 operational staff will take part - 10-25 people per region.

The strike will involve members of control centre staff who monitor the road network's CCTV and do a number of jobs including programming the electronic warning signs we see on major roads. Traffic officers who work in the aftermath of accidents will also stop work.

In the air

There's good news for travellers using Heathrow.

A 72-hour strike by baggage handlers from staff working for Menzies Aviation has been called off after talks between the private contractor and the Unite union.

Unite said the decision was a "gesture of goodwill" after a revised pay offer, which it will now ballot members on.

Driving tests cancelled

Civil servants in the Public and Commercial Services Union (PCS) - including driving examiners - are striking most days now until early January.

But the industrial action is regional - with different areas affected each week. This week, until Sunday 18 December, the walk out is in north-east England and Scotland.

The government said the union's demands were "unaffordable".

Bus drivers

Drivers in south and west London who are in the Unite union and work for operator Abellio will walk out for 48 hours in a dispute over pay.

Areas affected include Battersea, Beddington, Hayes, Southall, Twickenham and Walworth.

Unite said it had invited Abellio to pay talks in September but had no response, and accused the company of paying among the lowest rates for bus drivers in London, causing a severe "retention crisis".