Alternative Transit Modes

As I explained in an earlier guideway post, Sound Transit chose light rail technology to make it easier to use the existing transit tunnel and to run and stop at grade but many new technologies have been developed since. As Sound Transit builds a lot more elevated and tunneled sections and opens new lines in urban areas, it may need to reevaluate that decision. Sound Transit and Metro already use buses, heavy rail (for Sounder), ferries, and trams. Other cities like San Francisco, Mexico, and Paris use even more different modes like people movers and gondolas. In that post I talked about monorail and maglev guiderail systems. They are easier and faster to build due to prefabricated guideways, are slicker and therefore visually less obtrusive, and may offer easier maintenance.

As Sound Transit is facing escalating construction costs and feels it cannot accommodate traditional elevated trains downtown, it may be a good time to evaluate these and other alternative transit modes. Monorail systems have opened in Bangkok, and TSB has built a maglev test line in China and is looking at several options in Germany. Swyft Cities (working with Whoosh Solutions) and Ottobahn are working on cabins which hang from a guideway like the Wuppertaler Schwebebahn and provide personal rapid transit (PRT).

Similar to a Waymo or Zoox robotaxi, Swyft Cities and Ottobahn offer more route flexibility, are called via phone app, and have small individual cabins with an electric motor. Unlike a robotaxi, they use airspace and don’t get stuck in traffic, they are confined to its track network, have specific parking/staging areas, use electric motors with track power, and use small stations. While Swyft cabins travel on fixed cables (similar to a gondola or the RopeTaxi but those are propelled by the cable), Ottobahn cabins travel on regular tracks at 37mph. For longer distances Ottobahn claims up to 150mph. Both use track switches to guide cabins to their destination.

Ottobahn cabins hang off a bogie which is powered by an electric motor with regular wheels and steel tracks. Cabins either stop at elevated stations or can employ a lift mechanism which drops the cabin to the sidewalk for on- and off-boarding. Ottobahn claims they can support 6000 riders per hour in each direction, or even more with a favorable network design. Similar to a monorail, their track is supported by towers about 120ft apart and between 15 and 30ft high. The track can also cross longer distances over rivers and other obstacles akin to a suspension bridge. Cabins can usually climb up to 7%, with extra support even 12%. That may allow a ship canal crossing.

Swyft is hoping to start projects in Queenstown, Miami, or Los Angeles. Ottobahn started construction of its first network in Phuket.

Traditional train lines serve stations along a linear corridor. Turning a train around at the end of the line takes time as the operator usually has to switch from one end of the train to the other. Lines may branch towards the outer area of a network, but that splits the headway on each branch. As automated train systems do not need to worry about a driver, they can switch direction more easily and offer a bit more flexibility. For example, they can serve short stub lines by backing in and out, though that may impact travel time. PRT systems are not bound to any fixed line/schedule, can use a more elaborate track network, branch on demand, skip stations, and only stop as necessary. Though each cabin may be smaller, short headways may still allow for sufficient capacity.

Any of these systems promise simpler/faster guideway and station construction, easier integration into the existing urban infrastructure, more flexible branching capabilities, and more convenience for riders. It may be worthwhile to consider them for West Seattle or Ballard and other future lines.