Trains for the curvature of the Shasta Route -
the problem and the fastest solution
The old Shasta Route of the 19th century has had three parts with a huge number of very tight curves:
- The Sacramento River Canyon north of Redding.
- The crossing of the Siskiyou mountains.
- The Cow Creek Canyon in central Oregon.
When the Shasta Dam was built, Southern Pacific replaced the southernmost track in the Sacramento River Canyon by a new line, that circles around Shasta Lake with lots of tunnels. Most of the Sacramento River Canyon was never bypassed, though. Between Delta, a few miles north of Shasta Lake, and Mott, a little bit south of Mount Shasta, there are 95 curves with a radius of 574 feet or less.
Sensor-controlled tilting systems can have problems with such tight curvature. They work well with nice transition curves, accompanied with a superelevation ramp, that matches exactly to the transition curve. In very tight S-curvature, compromising might be unavoidable, though. The best solution for such situations is a tilting system, that does not rely on sensoring, but on a track database and position checks. Such trains have been developed in Japan and Spain.
Japanese tilting trains, like those used for the "Super Ozora" service between Sapporo and Kushiro, would be very well suited to the Shasta Route, after adaption to normal gauge:
- They are built for a minimum curve radius of 262 feet.
- At 14.7 hp/ton, they are capable of operating on the grades of the Shasta Route.
- With an angle linked steering bogie and only 48.4 tons per car, these trains achieve their high curve speeds on a less than perfect trackbed.
- The body shell of Japanese narrow-gauge trains is about as wide as European normal-gauge stock.
- The restriction to 81 mph in Japan is just a function of the required braking distance on the old parts of the Japanese network: 1968 feet.
As explained on page 15, lightweight tilting DMUs loose their advantages by adaption to the FRA body shell strength ruleset. Without a modernization of the rules, operations like the "Super Ozora" of JR Hokkaido aren't feasible in the USA.
This document assumes, that usage of the fastest trains for the Shasta Route is no realistic option. Adapting to reality, the author will try to indentify the fastest kind of trainset for this route, that is compatible with the current FRA ruleset.