EU referendum: Heathrow runway decision left up in the air

Britain's vote to leave the EU will potentially have far-reaching implications for the country's transport system.

Perhaps, most pertinently from a timing point of view, is what happens to Heathrow?

The west London airport was favourite to be picked as the site for a new runway, with the government talking about making a final decision this year, possibly even this summer.

But that was when David Cameron was in charge. Boris Johnson has promised to lie down in front of bulldozers to stop expansion.

It is bound to form part of the Conservative leadership campaign. If so, you can forget an early decision.

If Mr Johnson is the new PM, that would seem to kill off Heathrow's chances. Rival Gatwick is very much back in the game.

Also vulnerable, though much further along in terms of process, is the promised investment in high speed rail (HS2).

A government source has suggested that this vote won't affect funding. However, HS2 is yet to be voted through Parliament and the new prime minister will have her or his own spending priorities.

Investment in Britain's train services is also open to question.

Many of the country's rail franchises are already controlled and operated by European state-owned companies from Germany, the Netherlands and France.

They all got the chance to bid for the business because of EU competition rules. In future, however, will that still be the case?

I asked the transport secretary that question a few months ago. He wasn't quite sure.

It is also unclear what will happen with the car industry.

New cars currently have to pass a European emissions test before they can go on sale.

Frankly, it's done a poor job of protecting the air in recent years, even carmakers say it's too weak, which is why it's being tightened up considerably, starting in 2017.

So will our future cars have to pass the new, tougher EU pollution test?

One expert told me it's likely to stay in some form, otherwise we wouldn't be able to sell UK-built cars across the rest of Europe.