A short post on short trains

Automation, signaling, and frequency

• Many commenters note the argument mainly applies to fully grade‑separated, driverless systems; for new Western lines, automation is framed as a “no‑brainer” due to labor costs.
• Modern CBTC/moving‑block signaling can support high frequencies (30–40 trains/hour claimed), but others counter that >30 tph is rare and constrained by physics: braking, dwell time, and clearing platforms.
• Terminal and yard capacity, not just signaling, often caps throughput.

Small vs large trains, stations, and long‑term capacity

• Core claim: short trains + frequent service + smaller stations = cheaper construction and better rider experience.
• Some agree that frequency is what attracts riders and that smaller, automated “light metro” is a sweet spot.
• Others argue underbuilding is dangerous: Singapore’s Circle Line and Vancouver’s Canada Line were built with short trains and small stations, hit capacity quickly, and are now hard/expensive to expand.
• Debate over whether to “build big once” (long platforms from day one) versus start smaller and add lines later; critics stress retrofit costs and induced demand making later fixes painful.

Elevated vs underground

• Some praise elevated lines (views, lower cost than tunneling) and note they can work well in cities like Chicago and Vancouver.
• Others describe older elevated structures as ugly, noisy, sun‑blocking, and harmful to street life and property; modern concrete guideways are said to be less intrusive.
• Demolition for new elevated routes is compared to freeway projects that destroyed neighborhoods.

Buses, vans, BRT, and capacity math

• A self‑driving van vision is proposed as “the best train”; pushback focuses on capacity limits and higher per‑passenger maintenance (tires, roads).
• Disagreement over whether trains are really cheaper than buses; pro‑rail commenters cite vehicle lifespan, driver cost per passenger, and station throughput.
• BRT is described both as a legitimate cheaper alternative and, by others, as a political tool to block rail, especially when “BRT features” get watered down.

User experience, politics, and odds and ends

• Wait time and street‑to‑platform time are repeatedly called critical; a 10‑minute ride every 30 minutes is effectively a 40‑minute trip.
• Union rules and staffing expectations are cited as barriers to automation in some US systems; others note automated or single‑operator examples already exist.
• Several speculative ideas (split platforms, trains longer than stations, roller‑coaster profiles) are discussed but generally viewed as operationally complex or marginal in benefit.