Earlier sections along the beginning of the Orange Line (where the trackage exited the tunnel to the Washington Street crossing... about a mile in length) utilized lots of CD 269 Jumbo insulators. The porcelain "cleat" style insulators you see were quite common along stretches of the Orange Line Elevated (where the CD 267.5s and many CD 267s were located) . They were used as replacements for broken glass examples and further down toward the end of the line (almost exclusively) probably on account of better reliability (and availability) compared to the glass pintypes that were mounted in very similarly-designed cross-timbers. I have no documentation as to where on the Boston system this image was taken.