National Grid will be replacing an existing gas main on Littleton Road (Route 110) between the Nashoba Valley Technical High School and the intersection of Littleton Road and Tadmuck Road.  The work is expected to continue through the end of May and is being done in advance of the intersection improvement project at Littleton Road & Tadmuck Road.  All businesses will be fully accessible throughout construction.  Motorists should expect delays in this area and plan extra time for commuting.  Please drive with caution through the construction zone.