The LRC (a bilingual acronym: in English: Light, Rapid, Comfortable; in ) is a series of lightweight diesel-powered passenger trains that were used on short- to medium-distance inter-city service in the Canadian Provinces of Ontario and Quebec.
LRC was designed to run with locomotives, or power cars, at both ends and provide service on non-upgraded railway routes. To accomplish this, the LRC passenger cars feature active-tilt technology to reduce the forces on the passengers when a train travels at high speeds through curves. LRCs have reached speeds as high as on test runs.
On its only regular service route, on the Quebec City–Windsor Corridor, wear concerns, signalling issues and conflicts with slower-moving freight trains limit this to or less. For service at these speeds, a single power car was used. Special signage allowed the LRC to run at higher speeds than normal traffic across a great portion of the Corridor when the tilt system was enabled.
The LRC locomotives and passenger cars are compatible with conventional equipment. While the last LRC locomotive was removed from service on 12 December 2001, the passenger cars are still in widespread use and form the backbone of Via Rail's services, albeit with the tilt system disabled. The same basic car forms the basis of the Acela in the U.S.
History
Problems with speed
As a vehicle turns it generates centrifugal force, which is proportional to the square of the speed and inversely proportional to the radius. Even a small amount of force, acting across the length of the human body, creates a moment that can make moving about difficult. Centrifugal forces are not normally an issue in an automobile because the occupants are seated, nor in an aircraft where the fuselage is tilted so the centrifugal force passes through the line of the floor. It is primarily a problem in high-speed trains, where passengers and attendants often walk about while the train is moving. The force also pushes the entire train sideways, leading to wear of the outer rail. This was not an issue on early railways where the speed was low, but gained importance as line speeds increased and the radius of curvature became tighter.
One solution is to place speed restrictions on curved sections of track; another is to bank the railbed on the curve, with the outer rail higher than the inner rail so the net force passes straight through the floor of the coach. Banking the track is known as "cant" or superelevation. These measures were gradually adopted on the railways between 1835 and 1860. The use of track cant can only be applied where the speed of the train is fixed in advance. Slower, or stationary, traffic sharing the same line will experience forces pulling inwards, and, conversely, faster traffic will still experience forces pulling outwards. Long experience has shown that, to avoid discomfort on slower trains, track cant should not exceed 6°; and, for trains moving more quickly, cant deficiency should not exceed 4.5°.
Dedicated high-speed railway lines were being constructed in Japan in the 1960s. Japan had previously used a but decided to lay entirely new standard gauge lines for these services, the Shinkansen. The lines were designed for a running speed of , using gentle curves with a minimum radii of , and entirely new signalling systems able to provide enough warning to stop a train at within . The Europeans were planning similar systems in several countries, while the UK, and Canada, could not justify such an expense given their passenger numbers.
Active tilt
Another solution to this problem had been developed in the 1950s but not widely used: tilting trains. Tilting trains rock into the curve to tilt the passenger cars the same way that a superelevated track would tilt them inward. Tilting systems had been introduced in service by the Spanish Talgo, but this system was "passive" and took some time to respond to curves. Great improvement can be made by making the system "active", reading the forces on the cars with sensors and quickly rotating them to the proper angle using hydraulic rams. British Rail ran an extensive experimental program on active tilt systems in the 1960s that was highly influential, and followed these studies in the 1970s with a new tilting train design, the Advanced Passenger Train (APT). The technical design objectives for the APT included a maximum speed 50% higher than existing trains, curving speeds 40% higher, all while running on existing tracks within the limits of existing signals.