This whole discussion stems from the first sentence in the introduction of the issue paper: Tacoma Link Integration with Central Link. It states:
Sound Transit’s existing Regional Transit Long-Range Plan calls for light rail transit (LRT) service to operate between downtown Tacoma and downtown Seattle.What this means is that ultimately Sound Transit's plan calls for a continuous light rail system between downtown Seattle and downtown Tacoma. And that means that the clear option for vehicle technology will be Central Link vehicles. The only real decision after that is how does this more heavy-duty rail infrastructure connect with the existing Tacoma Streetcar.
The two obvious choices are to either convert the Tacoma Streetcar to Central Link technology or to keep the Tacoma Streetcar the way it is, but require a transfer between the systems. And once that major choice is made, the long-range consideration of how many Central Link vehicles to operate with also comes into play. The following table breaks it down fairly well:
The shortcoming of keeping the Tacoma Streetcar technology is that passengers coming from Federal Way and other points north via Light Rail would have to transfer at Tacoma Dome station to finally reach downtown Tacoma. However, if the Tacoma Streetcar is converted to Central Link technology, the turn at 25th and Pacific would have to rebuilt and the stations would have to be modified to allow for larger trains.
If four-car trains Central Link trains were to be used in downtown Tacoma, then major reconfigurations of the downtown area would have to be undertaken.
Another consideration is whether the Tacoma Streetcar will be extended to points west or other places. If the existing system is converted to the Central Link technology that is what would have to be used in other extensions. As noted in a previous post, the ridership demand on the possible extension down 6th ave would require either coupled Tacoma Streetcars running every 6 minutes or just one Central Link vehicle running every 7.5 minutes.