Repeal the 79mph Rule

Current FRA regs limit passenger trains to 79mph, unless certain signaling improvements are implemented, such as in-cab signaling and positive train control. This is the lowest default speed limit in the Anglosphere. Canada’s VIA operates at 100mph in the Quebec City-Windsor coridor with standard lineside signaling. Melbourne’s V-Line operates at 160kmh using the same. And the UK operates at up to 125mph on lineside signals, with AWS (an older form of in-cab signaling) only deployed at select locations.

The 79mph rule doesn’t have much impact in the Northeast, where major corridors are already equipped with in-cab signaling. However, in the rest of the country it is the single biggest impediment to operating intercity and commuter rail at speeds which are competitive with off-peak automobile travel.

Most of the radial routes entering Chicago used to host passenger trains at 100-130mph. The Milwaukee and Pennsylvania both ran 100mph under steam. But today, those all run at 79. Illinois has spent close to $2bb upgrading it’s Chicago-to-Saint-Louis line for 110mph; this same speed could have been achieved with the stroke of a pen.

110mph on un-upgraded tracks with un-upgraded signals allows cities and states to bootstrap rail service in corridors where there may not be enough ridership to undertake a major capital investment up-front. It also obsolesces a lot of questionable rail projects. For example:

—There’s no need to build a new set of train tracks in the median of I-15 to serve Las Vegas; just run 110mph on the UP.

—There’s no need to spend billions to shave another half-hour off Seattle-Portland; just run the existing Talgos at 90-110 wherever the track is straight enough.

—FEC’s All Aboard Florida train, which is currently planned to operate at 110mph between Orlando and Cocoa and 79mph between Cocoa and Miami, can run 110 the entire way.

—Existing and future commuter rail in the Sunbelt and the Mountain West is a lot more attractive. SLC FrontRunner and NM Rail Runner can operate at 110. Houston can construct rail along 290 without having it carry fewer people than the current HOV express bus.

—Longer and more direct Midwestern services become economical. Chicago-Kansas City via Quincy or Fort Madison is one such run. Chicago-Minneapolis via Madison is another.

One thought on “Repeal the 79mph Rule”

  1. The 79 mph speed limit is not about PTC. It’s about a weaker and more straightforward train protection system called ATS, or automatic train stop. ATS provides automatic protection from SPAD, but not from overspeed. The legacy NEC has this system, as does the Southern Transcon, which is why the Southwest Chief runs at 90 mph. PTC requires the same functionality but also automatic protection from overspeed, including temporary speed restrictions caused by work zones.

    Also, there’s a very good reason not to run passenger rail on UP to Vegas: it would crawl. Even if the tracks were brought up to speed, passenger trains would get stuck behind freight trains.

    The Talgos on the Cascades are limited less by maximum speed and more by curves. Thanks to our dear friends at the FRA, the diesel locomotives are heavy and have high center of gravity, so they can’t do more than 6″ cant deficiency – and BNSF doesn’t allow them to do more than 5″ or else they’d get stuck behind freight trains. So the tilting Talgos have maximum cant deficiency that is completely standard for a non-tilting train.

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