Theresa May confirmed the government would "press ahead" with HS2 development and that it would "shortly take a decision on expanding Britain's airport capacity".
In the closing speech to the Conservative Party conference the Prime Minister said "big and sometimes controversial" decisions on infrastructure needed to be taken.
The £55.7bn HS2 project will create a high-speed line linking up London and Birmingham by 2026. The Prime Minister's backing of the line reaffirms Transport Secretary Chris Grayling's comments in July. He said there were "no plans to back away" from HS2 following criticism of the cost and impact on people living around the route.
UKIP Wales has called on the high-speed rail line linking London with northern England to be scrapped, instead suggesting money should be spent on upgrading the Welsh network instead.
Meanwhile, the Green Party's co-leader Caroline Lucas called May's big decisions "overpriced diversions".