The UK Government is expected to approve the first phase of the £32bn HS2 high-speed rail project this week.

The 100-mile rail project is planned to be built between London and Birmingham from 2016 to 2026 and, once completed, the rail link will reduce the journey time between the two destinations from 1 hour 23 minutes to 49 minutes. The rail line will have branches to Manchester, Leeds and may possibly be extended further north by 2033.

Consultants for the high-speed rail project have drawn up a plan to introduce double-decker trains of 400m long that can carry more than 1,000 passengers. UK transport secretary Justine Greening told the Sunday Times she was excited by the idea of "continental-style double-decker trains that immediately give you more seats and more space". The trains could also boast glass viewing ceilings and meeting areas.

The rail line will allow trains to run at a speed of 155mph, and the government expects that it will generate benefits of around £44bn for the UK economy. After completion, the HS2 is expected to replace six million flights and nine million road trips as travellers are expected to opt for rail journeys.

Last month the government revealed that it may consider drilling a 1.5-mile tunnel under the Chiltern Hills. The new tunnel could cost £500m and is expected to reduce the HS2 line’s environmental impact on the countryside. It will also allow the minimisation of some deep cuttings along the route, which will help meet the extra tunnelling expenses.

The Department for Transport has considered changes to the HS2 rail line’s design amidst opposition to the original rail route. The high-speed rail project has been opposed due to concerns about affecting the natural beauty of the countryside.

The latest review by Network Rail considered two alternative schemes, including a series of improvements to the existing West Coast Main Line (WCML).

Those who are opposing the project question the business prospects of the line and the UK government’s traffic forecasts that the existing intercity rail network will start to run out of capacity by 2025.