Would a light rail from Alewife to Lexington really make sense in the middle of Mass. Ave. and other streets? Or would the bike and hiking trail through Arlington Hts. be taken back to put in light rail? Is light rail quiet enough that residents who opposed the Red Line going through Arlington Hts. would not object to light rail in what is now the bike trail?
A corridor without stop requests every fifth of a mile, without left turning private cars in the way, without lots of traffic signals, is desperately needed to make light rail a success.
Any corridor feature of bus rapid transit that is not chosen will adversely impact light rail along the same route comparably. So a reasonably accurate preview of a light rail on Mass. Ave. could be done using BRT. Compared with light rail, the biggest disadvantage of BRT is labor, in the form of number of operators. Should passenger volumes be great enough, the BRT could be converted to light rail. (If the whole thing is a flop then it is quietly discontinued leaving no large and unusual infrastructure that has to be removed.)
Suggest putting Scotch Magic or similar "permanent" tape over the seams of the envelope to prevent machinery jamming of or tampering with important mail.