American ExperienceSignal school Clip: Season 29 Episode 11 | 2m 6s In this co-production with Retro Report, we visit the MBTA’s Signal Shop, where workers maintain the equipment that keeps the trains on track. Aired: 01/31/17 Rating: NR The full episode is no longer available for online streaming. Why? Please continue to enjoy extra(s) from this episode. The full episode is still available for purchase through the "Buy Now" links.Buy Now:PBSBuy DVDs AppleBuy on iTunes checkmarkAdd to WatchlistProblems Playing Video?Report a ProblemClosed CaptioningShare:Share this video on FacebookFacebookShare this video on TwitterTwitterShare this video on Google PlusGoogleShare this video via EmailE-mailEmbedEmbed Code for this videoEmbed CodeAmerican ExperienceSignal schoolSeason 29 Episode 11Width in pixels px Height in pixels px Copied to your clipboardUnable to copyLabelCopy to ClipboardClick to copy embed code for videoCloseCloseReport a ProblemBefore you submit an error, please consult our Troubleshooting Guide.Type of ErrorVideo doesn't loadVideo loads, but doesn't playVideo jumps back/forwardOnly audio is streamingSponsorship playback errorOtherPlease add more detailsCancelSubmit ReportYour report has been successfully submitted. Thank you for helping us improve PBS Video.CloseCloseClose Learn More Down StartUp Success Story The Boston subway system is one of our nation’s oldest startup success stories. The Race Underground, Chapter 1 The dramatic story of the nation's first subway, chapter 1. The Race Underground promo The dramatic story of the nation's first subway.