(ShareCast News) - Transport for London has agreed a £500m deal with contractors Costain, Morgan Sindall and Skanska to carry out major road improvement projects over the coming four years.The framework agreement, covering the construction, upgrading and maintenance of bridges, tunnels and highways across the capital, may be extended by two years at TfL's discretion.TfL said part of the framework will be aimed at improving safety and reliability of the highways and byways while also encouraging cycling and walking.Projects could include the proposed Fiveways scheme in Croydon, the removal of the Vauxhall gyratory, as well as major renewal and upgrades programmes such as on the A40 Westway flyover.TfL said each contractor had been chosen to bring "something unique to the table" and all have experience in designing and building major schemes.Costain chief Andrew Wyllie said the contract win was "a reflection of our strong track record in applying innovative techniques in highways".Morgan Sindall's infrastructure boss Nick Fletcher added: "The projects within this framework call upon a wide variety of expertise, including highways, bridge and tunnelling skills - all of which we are well-placed to deliver, having a strong project history with similar schemes."