by jbvb
Short stretches of single track typically aren't big operational issues. I've ridden the Eastern Route off and on for 40+ years, and you're more likely to wait at Beverly Jct. than at either end of the Salem tunnel. Waltham is at a similar level. In terms of delays and train density, the two biggest north side capacity problems are Andover St. - Wilmington Jct. and Sullivan Sq. - Oak Grove. The former is in the works, the latter could be helped a lot for not much money by making the Medford Branch running track a CTC siding and scheduling meets there. Neither is really a prerequisite for Plaistow, NH service because that isn't expected to increase the number of trains on the Western Route; they'll just have to add 15 - 20 minutes to each round-trip time. The extra capacity Plaistow needs is extending double track a couple of miles beyond the current end at the NH 121A crossing. Otherwise, freights and DEs waiting for the single track to Rockingham Jct. will have to mix it up with commuter rail between Hall and Plaistow. Regrettably, Guilford's past behaviour suggests that this will take years and platoons of lawyers to get into service, once money becomes available.