Mass. Gen. Laws ch. 160 § 134A
Tracks in a yard or yard area owned and maintained by a corporation or company operating a railroad shall have a minimum distance between center lines of parallel tracks of not less than thirteen feet, plus one inch per degree of track curvature. The center line of any ladder track, or lead track, constructed parallel to any other adjacent track shall have a clearance of not less than seventeen feet from the center line of such other track. Platforms or buildings may be constructed or maintained at a minimum distance of five feet nine inches from the center line of the track adjacent to any such platforms or buildings, providing a clearance of not less than eight feet six inches, plus one inch per degree of track curvature, is maintained on the opposite side of such track to any fixed structure, or the track centers to an adjacent track are not less than thirteen feet, plus one inch per degree of track curvature.
No other structures or obstructions shall be maintained in such yard nearer than eight feet and six inches, plus one inch per degree of track curvature, from the center line of any track; provided, that signals and switch stands therein which are located between tracks and are three feet or less in height above the top of the rail may have a clearance of not less than six feet and six inches, plus one inch per degree of track curvature, from the center line of track where it is not practicable to provide the aforesaid clearance of eight feet and six inches. No bridges, viaducts or other obstructions shall be constructed, and so far as practicable, no bridges, viaducts or other obstructions shall be reconstructed over the tracks in a railroad yard at a height less than twenty-two feet and six inches measured from the top of the rail. Upon petition of any railroad corporation, the state department of highways, the metropolitan district commission, the county commissioners of any county, the selectmen of any town, the city manager of any city having a Plan D or E charter, or the mayor of any other city, the department of telecommunications and energy, after due notice and public hearing, may grant an exemption from any and all requirements of this section; provided, however, that any exemption so granted shall be limited to the specific location described in said petition; and provided, further, that the department of telecommunications and energy shall fix and prescribe reasonable regulations governing the location exempted.
Mass. Gen. Laws ch. 160, § 134A