I appreciate the inclusion of a Text Only link on your Trip Planner web site, because I often use a text only browser. I know that this also helps visually impaired people using screen readers, and people using older computers or slower Internet connections.
However, the Text Only link itself actually does not show up when you are using a text browser! This is because the link is in a <map> HTML element. I tried 3 different text browsers, the most popular ones, and none of them display the ALT text for <map> elements. They all show something useless and cryptic like, "[MAP]". I'm guessing you only actually tested this site in a graphical browser with images turned off, not in a fully text-based browser (like the programs "w3m", "links" and "lynx").
From the W3C's HTML Techniques for Web Content Accessibility Guidelines 1.0 (http://www.w3.org/TR/WCAG10-HTML-TECHS/):
Until user agents render text equivalents for client-side image map links, provide redundant text links for each active region of a client-side image map. [Priority 3]
So, the first problem is that text browsers don't display the Text Only link, which means it's only available to people who already know the URL and can put it in by hand. The solution to this is to provide redundant text links. The W3C accessibility guidelines explain how to do this. This would not change the look of your site at all.
Thanks for thinking enough to include the Text Only link. The MBTA already gets criticized for accessibility at its physical stations, and is taking action to address those criticisms; I hope you'll consider these suggestions for its virtual station as part of this effort to make the T fully accessible to everyone.
The MBTA responded immediately to my pressing of the Submit button on the feedback form. Their response?
An error occurred on the server when processing the URL. Please contact firstname.lastname@example.org.