Heathrow Airport Ltd (HAL) has outlined two detailed delivery schedules with varying budgets as part its expansion plan.

HAL’s Initial Business Plan reveals detailed costings for its third runway proposal for the first time, including plans for rail links from the west and the south of the airport.

The plan submitted to the Civil Aviation Authority (CAA) outlines two potential delivery schedules, one which focusses on cost savings and the other which prioritises services and would require additional investment.

The first plan would allow Heathrow’s third runway to open in 2028, while under the second plan the additional runway would not be operational until 2029.

HAL claims the first delivery schedule can still be delivered within the original £14bn price tag given in 2014.

However, the second, more expensive schedule involves spending an additional £3bn over the first 15 years including investing £750M each in western and southern rail links.

Under this delivery schedule a western rail link would be completed in the mid-2020s ahead of the third runway opening, with a southern link scheduled to be completed in the mid-2030s.

The plan states: “We are working with DfT to create new airport rail links. A Western Rail link to Reading would allow passengers to travel to the airport from the South Coast, South West, South Wales and West Midlands without going into London.

“In the 2030s a Southern Rail link connecting the South West and Waterloo to Heathrow is also planned.”

It adds: “We assume building Western Rail in both options, but our contribution varies. Investment in any Southern Rail Link also varies by option.”

Both delivery schedules include improving road links to the airport, including creating two new junctions on the M25 as well as constructing a Southern Road Tunnel which would connect the airport’s central terminal with the M25 traffic travelling from the south.

Changes to the airport’s infrastructure including carparks and access roads is also included as part of both delivery schedules.

HAL chief executive John Holland-Kaye said: “This plan ticks all the boxes. New capacity at Heathrow will help drive down airfares, attract up to 40 new long haul as well as more domestic routes and connect all of Britain to global growth.

“It delivers a sustainable airport at the cost we said without a penny of taxpayer money. Expanding Heathrow will make Britain the best connected country in the world, at the heart of the global economy.”

In December, HAL announced that it was pushing back the completion of the third runway from 2026 to “early 2028 or late 2029”, after the CAA ruled that Heathrow’s timeline should be adjusted to allow for the Planning Inspectorate to rule on its development consent order (DCO) application.

It said that cost increases to early construction work had increased the risk that the project would incur “significant” sunk costs. It comes after pre-construction costs in relation to HAL’s planning application rose to £2.9bn in July.

The CAA has introduced a series of measures in recent weeks to ensure Heathrow’s expansion is delivered in an efficient manner.

As revealed by New Civil Engineer last month, the CAA has brought in an independent assessor to determine whether Heathrow’s terminals could be operated by different companies.

The CAA has also revealed that Heathrow Airport Ltd (HAL) will be fined if its expansion costs rise above what has been agreed with the aviation regulator.