Airport Express/Silver Line Light Rail Conversion
Recently, I had the opportunity to visit Seoul and ride its wonderful metro system. One of the highlights was AREX, an airport railroad connecting Seoul to the international airport in the neighboring city of Incheon. A trip from Terminal 2 to Seoul Station is nearly 40 miles and takes about an hour, stopping at all stations. The trains come roughly every 10 minutes all day, not counting the nonstop service.
To contrast, Logan Airport has two MBTA options for getting to Boston, neither of which are anything like AREX. The Blue Line is fast, but drops passengers far away from the terminals, and the airport buses from the station can take up to 30 minutes to squeeze through traffic. The Silver Line, being a bus, suffers from the same problem, plus the traffic in the Ted Williams tunnel and on the streets of the Seaport. The MBTA schedules this trip to take roughly 20 minutes from Terminal A to South Station, but it frequently feels more like 40 minutes from my experience.
Even assuming that the MBTA's estimates are reliable, that is 20 minutes for 4 miles (average speed 12mph), vs 60 minutes for 40 miles for AREX (average speed 40mph). Surely there must be a faster way to get to the airport!
In black are the existing Silver Line rights of way. Light rail tracks would be laid here, including passing tracks at Courthouse and possibly World Trade Center, if there is enough space.
In grey is the existing Ted Williams tunnel, with tunnel extensions at either end to complete the Airport Express part of the line. On the southern end, a tunnel would be dug from the World Trade Center station to the exposed section of I-90, where the tracks would take over the eastern tunnel under the harbor. Road traffic would be funneled into the western harbor tunnel. On the other end, a new tunnel would be extended from the end of the eastern harbor tunnel under the tarmac and between Terminal A and Terminal B. To save money, this could be a cut-and-cover tunnel. A new underground Airport station would be built under the road between the two halves of Central Parking, allowing riders to connect to all four terminals on foot. This would be the terminus of the Airport Express service.
In brown is a connecting tunnel or viaduct which would allow trains to travel onwards to the existing busway in Chelsea without entering mixed traffic. It would have stops at the original Airport (renamed Bremen after the nearby park) and Wood Island stations for Blue Line connections. To cross Chelsea Creek, where SL3 is frequently delayed by drawbridge raisings, the route would require either a high viaduct or a deep tunnel. Either way, the route would return to ground level at Eastern Avenue station.
To contrast, Logan Airport has two MBTA options for getting to Boston, neither of which are anything like AREX. The Blue Line is fast, but drops passengers far away from the terminals, and the airport buses from the station can take up to 30 minutes to squeeze through traffic. The Silver Line, being a bus, suffers from the same problem, plus the traffic in the Ted Williams tunnel and on the streets of the Seaport. The MBTA schedules this trip to take roughly 20 minutes from Terminal A to South Station, but it frequently feels more like 40 minutes from my experience.
Even assuming that the MBTA's estimates are reliable, that is 20 minutes for 4 miles (average speed 12mph), vs 60 minutes for 40 miles for AREX (average speed 40mph). Surely there must be a faster way to get to the airport!
The Idea
The Silver Line already has a tunnel under the Seaport and a busway in Chelsea. Why not connect the two with the power of light rail?
This plan proposes that the Silver Line services that pass through Logan Airport (SL1 and SL3) should be converted to light rail and given a dedicated right of way for the entire route. This would allow faster average speeds for two reasons:
- Trains on dedicated tracks don't get stuck in road traffic
- Trains don't require careful steering in tunnels
Additionally, a dedicated right of way means that the MBTA can predict travel times much more reliably, and can run a more frequent service. To avoid digging a new harbor tunnel for this right of way, we can even re-purpose one of the two tubes of the Ted Williams tunnel!
SL1 would become the Airport Express, a limited service which stops only at South Station and a new Airport station. SL3 would become the normal, local Silver Line service, with frequent trains and many stops between Chelsea and South Station. SL2, the odd man out in this scenario, would likely need to be converted to a street-running bus.
The map below shows the details of the route:
In black are the existing Silver Line rights of way. Light rail tracks would be laid here, including passing tracks at Courthouse and possibly World Trade Center, if there is enough space.
In grey is the existing Ted Williams tunnel, with tunnel extensions at either end to complete the Airport Express part of the line. On the southern end, a tunnel would be dug from the World Trade Center station to the exposed section of I-90, where the tracks would take over the eastern tunnel under the harbor. Road traffic would be funneled into the western harbor tunnel. On the other end, a new tunnel would be extended from the end of the eastern harbor tunnel under the tarmac and between Terminal A and Terminal B. To save money, this could be a cut-and-cover tunnel. A new underground Airport station would be built under the road between the two halves of Central Parking, allowing riders to connect to all four terminals on foot. This would be the terminus of the Airport Express service.
In brown is a connecting tunnel or viaduct which would allow trains to travel onwards to the existing busway in Chelsea without entering mixed traffic. It would have stops at the original Airport (renamed Bremen after the nearby park) and Wood Island stations for Blue Line connections. To cross Chelsea Creek, where SL3 is frequently delayed by drawbridge raisings, the route would require either a high viaduct or a deep tunnel. Either way, the route would return to ground level at Eastern Avenue station.
Why is it Implausible?
It goes without saying that converting an already-congested highway tunnel to rail only for the sake of saving money on construction would be controversial at best. Though a better service to the airport would take cars off the road, it is impossible to tell if that would match half the number of people who currently use the Ted Williams Tunnel. Additionally, tunnel construction under airport tarmac would delay flights to and from Terminal A, and construction work on airport roads would temporarily increase the traffic there.
Additionally, tunnel or viaduct construction through East Boston would suffer from many of the same traffic issues, and tunneling deep enough or bridging high enough over Chelsea Creek to allow ships through could prove prohibitively expensive. Connecting to the old Airport station and Wood Island would also require constructing pedestrian bridges or tunnels through elevated highways, resulting in yet more traffic.
For now, I can only dream that someday there will be an easy way out of Logan Airport. Until then, I will continue waiting for the next Silver Line bus, forever twelve minutes away.
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