PERCHED on the edge of the stormy Atlantic, they have long been considered the rugged jewels in Scotland's crown.

Now ambitious plans to bind the Western Isles with a network of bridges and causeways are a step closer to reality.

The multi-million pound scheme would form a spectacular chain of roads all the way from the Butt of Lewis to the sparkling white sands of Vatersay, allowing drivers to travel seamlessly from one end of the Outer Hebrides to the other.

It promises to be one of Scotland's most spectacular road trips - and tourism chiefs are already hailing the potential boost to visitor numbers.

Ian Fordham, chairman of Outer Hebrides Tourism, said it would be an "investment for the future", and could prove a more cost-effective option than increasing the number of ferry trips.

He said: "We know that the Sound of Harris ferry is always a bottleneck. The ferry is pretty much fully booked all the way through summer. This would really enhance the visitor experience."

Plans to link the islands are among 11 priority projects listed by Western Isles Council as part of a proposed "Islands Deal" aimed at mirroring similar investments in Scotland's cities.

Edinburgh secured a £1 billion package last year, including £20 million for a new 1,000-seater concert hall and substantial investment in road infrastructure. Glasgow has seen similar funding.

Now the Western Isles, Shetland and Orkney are pushing for their own scheme, and representatives from the islands met with civil servants from both the UK and Scottish governments in January.

While no details are set in stone, proposals to build fixed links over the Sound of Harris and the Sound of Barra have been outlined, connecting Harris to North Uist and South Uist to Barra.

This would allow drivers to travel the full 175-mile stretch of the island chain for the first time, taking in some of Scotland's most celebrated scenery.

A report drawn up by council officials last week said a formal commitment from the UK Government for any Island Deal in unlikely to be in place until next year - but insisted other funding could be made available before then. It also noted the "level of funding being sought is high, particularly from the Western Isles".

Other projects prioritised by Western Isles Council include a regeneration scheme in Stornoway and the UK's first designated spaceport.

Mr Fordham said fixed links between the islands had been "on the agenda for a while" but had always come with a large price-tag attached. An Island Deal could finally overcome this hurdle by providing investment. A Western Isles Council spokesman confirmed building the links was one of the priorities in any wider deal.

He added: "We've done bridges in the past, and we've done causeways in the past. But we're not really at the stage of details."

He said earlier plans for a 15-mile tunnel between North Uist and Skye - connecting the Outer Hebrides to the mainland - had "dropped out as a priority".

A Scottish Government spokeswoman said: "We are committed to working with Comhairle nan Eilean Siar [Western Isles Council], Orkney Islands Council and Shetland Island Council on an Islands Deal, and looks forward to receiving the detailed proposals the three island local authorities have been working on in the coming months."

It is not known how much money could be made available as part of any Islands Deal, but officials have confirmed rural areas will not be given less simply because of their smaller populations.

The latest move comes as legislation aimed at handing greater powers to the islands continues to make its way through parliament.

HeraldScotland:

ANALYSIS: Building causeways is cheaper but the conditions need to be right

LINKING the Outer Hebrides would be an expensive project – but it can be done.

That’s the view of Ronnie Hunter, the former chairman of the Institution of Civil Engineers in Scotland.

He told The Herald a causeway, rather than a bridge, would provide the most cost-effective option – but only if the conditions are right.

He said: “The easiest one, if it can be done, is the causeway – because essentially you pile rocks into the sea and drive it out from the land.

“If you protect it properly, a causeway is probably the cheapest to maintain. It would probably be more expensive to build a bridge.

“There are precedents for causeways but the conditions have to be right.”

Mr Hunter listed a range of conditions that would need to be kept in mind to ensure success, such as depth and ground conditions, weather and tidal and navigational factors.

He added: “A causeway is an embankment – usually made out of rocks – across the water, and you put the road on top of it.

“What are the hassles on top of that? Well, how deep is the water, because the volume of rocks you need is driven by the depth of the water.

“And if you put a causeway across, you are interfering with [boat] navigation. You are also interfering with the environment.

“A causeway is a big dam. If there’s a very high tide flow, then a causeway maybe isn’t the answer. So your next step would be a bridge.”

Mr Hunter – who once carried out a study into building causeways in Argyll and Bute – also raised some concerns over the distance which would need to be covered by any link.

Five miles of ocean separates the tiny island of Berneray, which is connected to North Uist, and Harris.

He said: “You would want to take into account the demand. Does the demand justify the cost? It sounds an expensive opportunity.

“It would need a study – but those studies can be done. They have been done before, and causeways have been built in the Western Isles and elsewhere before.”