An urban highway regeneration project in San José has become the first in California to be recognised for its sustainability efforts in design and construction.

Built by Pavex, a division of California-based Graniterock Construction, the 2.1-kilometre Monterey Road Reconstruction Project achieved a Greenroads Bronze Rating from Greenroads, a not-for-profit foundation formed by a number of industry associations and government departments in the US to implement the Greenroads rating system for road construction projects.

Built in 1912, the original four-lane section of Monterey Road between Blossom Hill and Bernal Roads was previously noisy and full of potholes and had the dubious distinction of being considered one of the worst roads in the state.

A key feature of the new construction work involved cold-in-place recycling, a pavement rehabilitation technique which involves the reuse of existing asphalt, which is then crushed, laid and compacted after the addition of either a virgin aggregate or recycling agent. The environmental and cost benefits arising out of this include the reuse of material as well as the avoidance of needing to transport material to site or use heat during the mixing process.

California Before Construction

Pavement condition before reconstruction.

Greenroads executive director Jeralee Anderson says around 97 per cent of the existing roadway was reused in this way, delivering savings of around 23 per cent on the project.

Other key features involved using a mix involving recycled rubber (19 per cent) instead of pure asphalt to provide two additional inches of surfacing in order to make the pavement quieter and the installation of LED street lighting with dimming controls.

Since its inception last year, Greenroads has certified seven projects, all of which are located within the United States.

A total of 23 additional projects have registered for certification, with a number of projects from Canada and New Zealand on the books as well as one from South Africa.