Red Line at 100

Yesterdays’s post about the Boston Trolley Meet was more about playing with the iOS WordPress app, and the HTML 5 <video> element, but it did remind me that there was another recent local centenary that I’ve been meaning to talk about: the 100th anniversary of the opening of the initial section of the MBTA’s Red Line. The original section of the Red Line opened from Harvard Square to Park Street on March 23, 1912.

One of the interesting things about the Red Line is that it’s the only one of Boston’s four subway lines to be designed as a rapid transit line right from the beginning. The Blue Line began life as a tunnel for streetcars; the Green Line still is, and the Orange Line ran through the Green Line’s Tremont Street Subway for its first seven years, meaning that the the rolling stock had to be sized for that tunnel’s tight clearances. Because the Red Line was rapid transit from the start, its designers were able to make design decisions unhindered by the dimensions of the trolley subway. The tunnels are bigger and the curves are gentler, allowing for higher speeds.

Another trade-off the Red Line’s designers made was to go with larger cars– Red Line cars are about a foot wider, four feet longer, and higher off the ground. This is a trade off: it means that while Orange Line equipment can be made to run on the Red Line in a pinch (although highly unlikely nowadays, given the difference in heights), Red Line equipment cannot run on the other lines. It’s a reasonable design decision though, given that there’s no room for a direct connection anywhere.

The corporate side of the system back then was interesting. Within the Boston city limits, all the design and construction of the subway system was under the purview of the Boston Transit Commission, and the tunnels were owned by the commission. It’s not clear to me whether the Commission was part of the City of Boston, or a commission of the city and state –both the mayor and governor appointed members. The Commission was chartered in 1894, and ran until 1918. The annual reports of the commission are online, and make very interesting reading. It’s clear that the whether the Commission was part of the City of Boston or not, the commissioners were able to exercise a great deal of autonomy.

The actual operation of the system was the responsibility of the Boston Elevated Railway (BERy), a private company, sometimes referred to as the El. BERy provided and owned the rolling stock, and furnished the equipment for the subway stations. The company built and owned the elevated lines, but paid tolls to the Transit Commission for the use of the Commission’s tunnels.

When first proposed, the El intended the line to Harvard Square to be another elevated line. Due to fierce local opposition, though, eventually it was decided to build the line as a subway, and unlike the Boston side of the river, the Cambridge side of the line was built by the company itself.

The line, as it originally opened, was in three segments. The Cambridge Main Street Subway was built by the El. It ran from Harvard Square, under Massachusetts Avenue and and Main Street. It was built using cut-and-cover methods, where a deep trench is dug, usually under streets, the tunnel built, and then covered back over. The El also built a tunnel to Brattle Square, connecting to a yard and maintenance facility at Eliot Square. In later years, during the Harvard football season, the El would run service to the storage yard, where there was a small platform; this was called “Stadium” station.

The second segment was over the Charles via the Longfellow Bridge. The bridge had been built earlier by the Cambridge Bridge Commission, but had been designed with a reservation in the middle intended for the future use of rapid transit.

The last section was the Cambridge Connector, built under Beacon Hill by the Transit Commission, and ending up under the existing Park Street Station. Construction of this started in 1909, after some delays caused by legal action (some things never change). The Transit Commission was sued by a couple of parties wanting the tunnel to go under Cambridge Street and connect to the East Boston Tunnel (now the Blue Line) at Scollay Square (now Government Center). The case lasted a little less than a year (some things do change) and was resolved in favor of the commission.

The Cambridge Connector was built via the deep bore method; this means a semi-circular tunneling shield was placed at the tunnel starting point, and then pushed forward as construction progressed to support the roof of the tunnel while the tunnel was dug and the walls of the tunnel were built. Amazingly, a lot of this digging was by hand.

Building the Red Line - workers tunneling under Beacon Hill. From the 1911 Annual Report of the Boston Transit Commission

The Park Street end of the tunnel was built in an open excavation, and the existing station had to be underpinned and modified to connect to the new station under it. That end of the Cambridge Connector had several design constraints. First, obviously, it had to connect with, and support, the original Park Street station. Second, even before it opened, there were plans to extend it via the Dorchester Tunnel, down Winter Street, under the existing Washington Street tunnel, down Summer Street, and under South Bay to Dorchester, so the initial segment to Park Street had to be deep enough, and properly positioned, to facilitate that. Finally, at the point when the Cambridge Connector was designed, a third subway, the Riverbank Subway, had been authorized, and it was contemplated that it too would terminate at Park Street, so allowance had to be made for that.

The Red Line has been greatly expanded since then. The Dorchester Tunnel opened in sections, ending at Andrew Square in 1918. The Dorchester Branch opened nine years later via a railroad right of way, first to Fields Corner, then a year later to Ashmont. The South Shore line was grafted onto it in 1971, and in the late 80’s, the original Havard Station was demolished, and replaced with a new station and the extension out to Alewife. But aside from Harvard Station, that original section is still in service today, and is still an essential part of the line.