Show historic speed on stretches of track

[devinmatte]

Some sets of track on the MBTA were designed for 50mph or higher, yet the MBTA maxes out at 40mph. We should look to call out what those stretches are.

Because we only have data back to 2016 for rapid transit, we may need to source this data from documents, but, it would be really cool to call out stretches where improvements are possible to improve people's lives

One document for example: https://bc.mbta.com/uploadedfiles/Business_Center/Bidding_and_Solicitations/Request%20for%20Proposals%20No.%20CAP%2027-10%20(Technical%20Provisions).pdf Outlines many parts of the Red and Orange line. Would be great to get help parsing out the stretches of track and their max speed on that stretch

Probably relies on #803 first being finished to actually add to the dashboard