A key decision over an ambitious �26m expansion of Norwich Research Park, which would create thousands of new jobs, will be made within the next fortnight.

The blueprint for the growth of the park has been hailed as a potential shot in the arm for the city and county's economy and councillors are to be asked to decide whether to give the first phase of the expansion scheme at Colney the go-ahead.

But the proposals have sparked concerns from some parish councils who fear the extra traffic generated will lead to clogged roads and rat-running.

Members of South Norfolk Council's planning committee will meet on Wednesday, January 9, to vote on whether to grant permission for what is known as the Norwich Research Park North development.

The radical plans for the expansion of the park, which could create more than 5,000 jobs, include new flagship buildings and upgrades to the park's IT infrastructure and road network.

Known as Project 26, the aim of the expansion is to kickstart development of the park to encourage more businesses to set up home there.

The application has been lodged by Norwich Research Partners, which is made up of the six institutions on the park – the Norfolk and Norwich University Hospital, John Innes Centre, Sainsbury's Centre, Institute of Food Research, the Genome Analysis Centre and the University of East Anglia – as well as land owners including the University of East Anglia, the Biotechnology and Biological Sciences Research Council (BBSRC) and the John Innes Foundation.

Some 2,700 scientists work on the park and more than 11,000 staff in total, but up to 2,800 more could be created through the first phase of the expansion.

The park was last year awarded �26m by the government, through the BBSRC, to help it attract more businesses.

South Norfolk Council officers are recommending that councillors approve the outline plans for what is known as Norwich Research Park North.

A number of existing buildings on the site, off Colney Lane, would be knocked down, with 65,000 square metres of new office space for research and development created.

Project manager Alan Giles previously said of the plans: 'The expansion of the park is a core part of our vision to develop a strong research-led business community in the life and environmental sciences.

'The future is bright, and if plans go well the knock-on effects could create 5,000 new jobs in the region over the next 10 to 15 years.'

The plans also include a new road from Hethersett Lane and changes to the existing access from Colney Lane. Other road changes as part of the scheme are planned for the B1108, the Old Watton Road and on Colney Lane and Hethersett Lane.

George Freeman, Mid Norfolk MP and a special adviser to the department for business, innovation and skills, has long supported the expansion of the park, which he says is vital to Norfolk's economy.

He said: 'The Norwich Research Park is a jewel in the Norfolk crown - with the world class science and innovation to create new products, markets, businesses, and jobs - across the medical, agricultural and environmental sectors.

'With the right infrastructure and high quality planning, we can create a world class 'cluster' of high growth small businesses and opportunities for the Norfolk economy over the next 50 years.

'But planning is critical to its success. These clusters need a high quality environment with green space, fast broadband, rail, road and bike links, and well planned housing.

'I know that South Norfolk Council are very aware of the importance of getting the research park right, and I look forward to seeing the park grow and prosper.'However, a number of parish councils have raised concern about the proposals. Colney Parish said it had supported the development in principle, but had to object because developers had not addressed their concerns.

Those concerns include that the scale of the development goes beyond the guidelines laid down for the site and that the impact of traffic on local communities has not been made clear.

Hazel Martin, parish clerk for Colney, said her parish meeting had called for a formal meeting between developers, council officers, parish councils and the highway authority to discuss the issues.

She said: 'Given that traffic assessments are essential components of obtaining planning permission... we regard such a meeting as essential if the planning process is to be legitimate and a democratic input is to be guaranteed.'

Cringleford Parish Council has similar concerns over traffic volume and whether there would be enough car parking on the site to prevent workers parking in neighbouring villages.

And Richard Sinclair, clerk to Little Melton Parish Council, wrote to planners at South Norfolk Council, with worries that Little Melton could become a rat run.

He wrote: 'The impact of substantially increased traffic in Little Melton seems to have been overlooked.

'The parish council has strong concerns that Little Melton will become a rat run with all the inherent problems that this brings, such as drivers having no concern for speed limits, increased traffic, larger vehicles and lorries.'

But officers, in recommending approval, said the developers have come up with proposals for highway works to address the 'inevitable increase in the use of the site by all forms of transport'.

Further jobs could be created by a second phase of expansion, on a privately developed plot next to the N&N hospital, with that scheme known as Norwich Research Park South.

Those plans are likely to come before South Norfolk councillors later next month, with Bullen Developments keen to build up to 100,000 square metres of offices and labs there, mainly for medical research.

Developers say that would lead to even more jobs, bringing the total which could be created by the expansion to more than 5,000.