Modern snowclearing concepts and equipment
Cost-efficient snowfighting uses 2 concepts:
- As long as possible, use the train's snowplow for clearing the track.
- If that's no longer possible, recreate a train path, that allows to use the train's snowplow as the clearing device again.
Lowest cost is achieved, if the train's snowplow clears the track. The task of a rotary is, to create free room, about 13 feet wide. If this width is provided, the loco's snowplow can throw the snow over walls of 8 feet height.
Clearing snow with the train's snowplow is almost for free. All it takes, is the proper design of new trains, with rather low additional cost. Freight locos in the USA are designed rather well for the task, at their speed level. For higher speeds, more pointy designs are required. The approach has its limits, though. Even with the best snowplow design, the acceptable snow height is lower at higher speeds.
At a certain snow height, the train's snowplow can no longer lift the snow over the "walls" right and left. Results are icy buildups, which will make trains stall, or derail them. On low-capacity lines with moderate snowfalls, the problem can be solved with a Jordan spreader. If snow heights are worse, or a high clearing speed is needed for a high capacity line, it is the task of a rotary.
Rotaries of the past have been expensive to operate, and the achieved result compared unfavourably to the cost. The single wheel couldn't be bigger than the loading gauge of the line. In order to create free space left and right, a "mouth" had to be formed, guiding the snow into the rotating wheel. This "mouth" created a huge resistance. Most of the energy put into the forward thrust was dissipated into compacting snow, heating it up a tiny amount before being rotated away. This is the reason, why huge contraptions out of a Leslie rotary and several locos were easily replaced by rather small modern devices.
Modern plows can push their rotary wheels to the left and right, where they "eat" the buildups outside of the loading gauge directly. As well, the design of the rotary wheel is more efficient. Due to this technical progress, modern rotaries clear 10 times the snow with a given horsepower, in comparison to an old Leslie.
Other measurements of efficiency are "cleared snow divided by hours of line usage" and "cleared snow divided by crew working hours". In high capacity line operation, there won't be more available time than an extra train path. The most powerful snowplows aren't used for mountain lines with the worst snow problems, but for clearing trunk routes within the shortest time possible.
Modern technology has made snowclearing a 1-man-operation, though a crew of 2 is still quite common. Short clearing times reduce labour costs as well, though this argument might not exist for some of the Class 1 railroads in the USA: They pay their crews by the mile, not by the hour, making it less attractive to invest into efficiency.
Railroads can always bring the heavier, more powerful and more efficient equipment. For this reason, plus the advantage of running on rails, some passenger railroad lines are operated under conditions, which force the closure of all road traffic.