it is called the nair orrownarr. it goes down to two lanes in each direction. it is a bottleneck and slows people down. but cal trans has a plan for it today and made it official in the most ceremonial of ways. >> one, two, three. >> reporter: along the sonoma and marin county borders a not so subtle contrast between the bigging of -- digging of dirt. the highway 101, the narrows, in the past 25 years traffic flow has doubled to 135,000 cars aday. >> it is a very difficult -- to traverse this corner right now. >> we're trying to make it bearable. >> reporter: the project will cost $735 million of state, local and some federal money. it will take about three years. is it an engineering marvel? they say no. >> not too difficult. it is just a chore. >> reporter: the improvements will straighten a sharp curve and widen and elevate the highway and build a new bridge above the flood prone creek. for cal trans, they are in charge of the project. >> this is exciting. >> she grew up in it india pushing around bump trucks before getting a master's degree at san jose stat