Shares in Sweett Group jumped almost 10% on Friday after the infrastructure and professional services provider said it had secured a new four-year contract with Network Rail.The London-listed company confirmed it had been re-appointed to provide to provide commercial management and estimating services on the £6.5bn Thameslink Programme, which aims to create a bigger north-south rail line running through the heart of Central London from Brighton to the south and Bedford to the north of the city.In 2006, Sweett Group was first appointed to the government-sponsored project by Network Rail to support to their programme and project teams in the form of pre and some post contract commercial management services.Under the terms of the new agreement, Sweett and a number of other firms will provide support on the delivery of a number of schemes, such as the rebuilding of London Bridge Station and infrastructure changes in the outer areas on the Peterborough, Cambridge, and Sussex routes.Sweett Group shares were up 9.46% to 20.25p at 11:13 on Friday.