An obsolete six-lane expressway that slices through East Somerville will, by the end of this summer, become a four-lane expressway with wide buffered bike lanes. MassDOT plans to repave McGrath Highway later this year, and when the project is over, the roadway’s stripes will be repainted in a new layout (pictured above) that will transform the highway’s outer lanes into new buffered bike lanes to accommodate Somerville’s growing volumes of bike traffic. “This project is an indication of how progressive and courageous MassDOT can be. The road diet is outrageously ambitious for a resurfacing project, and it’s an indication of their willingness to work with us for a safer, calmer McGrath Boulevard,” said Brad Rawson, Director Transportation & Infrastructure for the City of Somerville, in a phone interview on Wednesday morning.