Ask Me Anything: Simon Calder to answer your travel questions as Heathrow caps passengers until September

The mercury is rising - and, with it, the chance that your train will be delayed or cancelled.

On Monday and Tuesday, as temperatures are set to soar and potentially hit 40C in the UK, train operators are reducing services to cope with the heat.

Steel rails are susceptible to buckling under extreme temps; some companies will have to run trains at speeds as low as 20mph (instead of the usual 125mph) for safety reasons.

Meanwhile, passengers across certain parts of the country have been told to only travel by train over the next two days if their journey is strictly necessary, with Transport for London giving the same message to commuters.

So what does it mean for your imminent public transport journeys? And are you still allowed to travel by train?

Our expert Simon Calder will be on hand tomorrow, Tuesday 19 July, to answer all your questions in an ‘Ask me anything’ event, between 4-5pm. He will be answering live in the comments section below.

Register to submit your question in the comments box under this article. If you’re not already a member, click “sign up” in the comments section to leave your question.

Don’t worry if you can’t see your question – they will be hidden until Simon joins the conversation to answer them.

Then join us live on this page from 4pm as Simon tackles as many of your travel queries as he can within an hour.