CAMPAIGNERS claim Gatwick's expansion plans will require an additional £345 million of infrastructure spending.

Communities Against Gatwick Noise Emissions have rung alarm bells about huge new housebuilding plans which could add 69,000 new homes to the county and increase traffic clogging major roads.

Gatwick, which claims that all costs of the £7.8 billion expansion will be met by the private sector, claim the area will be road and rail ready in 2020 – five years ahead of any second runway’s possible opening.

The Gatwick Diamond infrastructure study authors estimate the area’s minimum infrastructure investment of £850 million would rise by 40 per cent to £1.19 billion with the second runway.

The expansion of Gatwick would require 52,000 new homes between 2030 and 2050 in addition to the projected 40,000 between 2015 to 2030.

Up to 69,000 of those homes could be built in West Sussex adding 20 per cent more homes to the area by 2050.

The report's authors warned significant new development could change the character of towns and villages making them less attractive while a new settlement might be necessary leaving councils, already struggling to accommodate growing populations, facing significant challenges.

The report also warns that sections of the M25, M23, A23 and junctions around Crawley will all be at or exceeding capacity by 2030 and may require “further enhancements”.

The report, commissioned by West Sussex and Surrey county councils, was due to be published in January but was only released earlier this month.

A decision on whether Gatwick or rival Heathrow will be chosen for expansion is expected within six weeks with MPs set to be given a free vote.

Gatwick bosses claim that expanding the Sussex airport will bring £90 billion of economic growth and create 120,000 new jobs.

CAGNE chairwoman Sally Pavey, said: “Gatwick has been quick to state that no Government funding will be necessary, but who is going to pay for the demands placed upon the county by an airport as large as Heathrow today.”

A Gatwick spokesman said: “The Airports Commission itself concluded road and rail improvements already underway or planned will more than meet the demand a second runway would create.

“Indeed, Gatwick will be road and rail ready for a second runway by 2020 which is five years before a new runway can be operational.

“With increased investment and projects already underway, Gatwick’s rail capacity is set to double by 2020, boosting growth and benefitting local rail users who can expect a significantly improved service in the coming years.”

Meanwhile, Gatwick bosses submitted fresh evidence to ministers claiming Sir Howard Davies' Airports Commission report from July last year was already out of date and had underestimated the airport's growth.