I was down at JFK the other day and I was looking around when I realized that there is only one track for the Old Colony line. Is it just a single track the whole way? This strikes me as odd seeing that there are 2, and some day three, branches.
This has been talked about before but I will put it like this.
The Old Colony is single tracked from the Southampton Yard to the Dorchester Armory. The line becomes double-tracked and is double-tracked over the Neponset river to just north of Wollaston Station, I believe the street next to the ROW is Newport Ave, and there is a Stop and Shop there. The line becomes single tracked again through quincy center and I believe is single tracked to the Braintree wye, where greenbush will branch off. It is double tracked from here through braintree station. There are two crossovers just outside braintree station, with the right track going to middleboro and the left track going to Kingston.