Cost has cast a question mark over full dualling of one of Cumbria's busiest and most controversial roads.

Although upgrading the A69 could cut journey times and bring much-needed jobs and investment to the county, a government study says it would turn out to be more expensive than another crucial scheme.

The alternative option of upgrading the A66, which links Scotch Corner to Penrith and west Cumbria, would cost less.

But the Northern Trans-Pennine Strategic Study states: "Completion of A66 dualling will generate around half the journey time saving of the A69 dualling."

Details of the costs have not yet been disclosed.

Experts have been analysing early findings of a study looking at road crossings between the north east and north west, the A69 and A66, as well as examining the potential to create a new or improved corridor in the region to link the A1 with the M6.

One option includes dualling the A69, linking Newcastle and Hexham with Brampton and Carlisle.

Currently, 32 miles of this road is single-carriageway.

This option could also include a junction improvement package on the A69/B6531, A69/A6079 and A69/A68, and dualling of the A689 or bypassing Warwick Bridge at the western end of the A69.

Option two dualling of the A689 would in Stage three combine into one Warwick Bridge bypass option which has a variety of delivery options.

Option three bypass of Warwick Bridge represents an option to upgrade the western end of the A69. This could be delivered in advance of the full dualling option.

Option four the junction improvements package could represent an option to upgrade the eastern end of the A69; could be considered as a stand alone scheme, as well as part of full dualling option and could be delivered in advance of the full dualling option.

Proposals to upgrade the A66 between Darlington and Penrith would see dualling of 15 miles of road, as well as a junction upgrade at the A66 with the A6. Alternatively the junction upgrade could be delivered as a stand-alone scheme.

Further options on the A66 could see dualling of Scotch Corner to Greta Bridge or dualling of Temple Sowerby to Brough. Both these options could be stand-alone schemes or delivered as part of phasing of the full dualling option.

A fifth option on the A66 would see a single carriageway bypass of Kirkby Stephen.

Initial findings suggest dualling of Temple Sowerby to Brough would generate a high proportion of A66 dualling journey time savings, due to current speed limits.

The Kirkby Stephen bypass would generate low journey time savings due to low traffic volumes.

Campaigners have argued for years that the two roads - both key arterial routes linking the county to the north east - should be upgraded to dual carriageway.

The A66 in particular is regularly blocked in winter by bad weather.

The study, led by structural engineers and consultants contracted by the Department for Transport, found that both routes were currently unreliable and suffered from above average numbers of crashes.

They say the benefits of the work as well as improving journey times would include cutting the number of accidents and ensuring there are fewer closures or delays caused by roadworks.

Rory Stewart, MP for Penrith and The Border, says he has long argued for improvements on both the A69 and A66.

"Firstly, I am very pleased that the Strategic Study Group have looked so carefully at these very important infrastructure options. As ever, it is a case of balancing need with available resources, and looking carefully at the road usage and prioritising accordingly," said Mr Stewart.

"On safety grounds alone, I would push for the solution that makes these roads safe for both drivers and pedestrians and, crucially, for those who live along the road," he added.

"The journey time savings that would result will also benefit our economy enormously."

Mr Stewart said investments needed to be bold. "We are looking for a long-term, lasting solution, and not a stop-gap."

He pledged to continue the fight alongside his fellow Carlisle MP, John Stevenson for the best possible plan for the A69. "One which will bring lasting results to residents and road users."

"I also want to pay tribute to the vision of the Department for Transport, and particularly the former Secretary of State Patrick McLoughlin, for committing an unprecedented sum to the strategic road network, in the region of £15 billion. The Northern Trans Pennine study is a significant step forward for our communities along these roads."

Improving east-west routes in the North is seen as key to improving economic benefits to the region.

"It's about infrastructure and investment," said John Stevenson, who added that the best option would be to fully dual the A69, including a by-pass of Warwick Bridge where residents had been campaigning for decades. "I appreciate it would be more expensive than the A66 option, but it's the one that has the most journey time saving. It would keep the journey down between Newcastle and Carlisle to one hour, and that would be hugely symbolic."

"It'll improve both business and tourism links between Cumbria and the north east, and is part of the Government's plans to improve Britain's infrastructure, and also support a northern powerhouse."

Former Chancellor George Osborne promised a business plan on the case for improving the A69 between Northumberland and Cumbria will be completed by the end of 2016 when he delivered a Budget statement in March.

He pledged £75m to develop a business case on transforming east-west road connections in the North including a new Trans-Pennine tunnel under the Peak District between Sheffield and Manchester, and enhancing the A66 and the A69.

A final report setting out the benefits and drawbacks of each option is not expected until late September or October. There will then be further development of options, which will include a public consultation.