Interface - The Journal of Wheel/Rail Interaction

STRESS REDUCTION

Reducing the Stress State on Canadian Pacific’s Western Corridor
By Mike Roney • July, 2009

Canadian Pacific has taken a unique approach to reducing the stress state in its western corridor. The approach includes the implementation of distributed power and the implementation of friction management. It also includes examination of their combined effects — something that is relatively new. Looking at CP’s operation from Vancouver to Montreal and into New York, this project is primarily focused on the Western corridor, running between Calgary and Vancouver and crossing over the Pacific mountain ranges as the traffic makes its way to the coast.

In this area, the ruling grades are 1.25% for westward traffic, and 2.4% for eastward traffic. It's a key area with heavy grades and high tonnage. Under these types of conditions we can clearly see the impacts of power configuration and under-speed conditions. Wherever there are heavy grades, there tends to be a lot of curves. In these types of areas, it is easy to see the accelerated wear, as well as the impacts of friction and friction management, and the impacts of distributed power.

The use of distributed power has attracted significant attention over the past several years. CP's objective in implementing distributed power in the western corridor was to take a scientific approach to appropriately powering the trains and achieving the lowest overall system cost. The key questions are: How does power configuration and train length affect fuel consumption, train velocity, train forces, and track costs? CP’s goal was to look beyond individual train performance and at optimizing the overall system.

In this project, work was done in conjunction with Applied Rail Research Technologies (ARRT Inc.) to look at the impact of the powering of trains, power positioning along the train, speeds, superelevation, angles of attack and drawbar forces, and to perform modeling with respect to balancing superelevation with train speed in both ascending and descending grade operations. ARRT's software showed CP that track costs are minimized when uphill and downhill trains run at close to the same speed.

The software also showed that in heavy grade operations, the interaction between ascending and descending speeds must be balanced. Uphill trains tend to lean on the low rail and produce high damaging loads, high angles of attack and truck skew. Downhill trains run at higher speeds and tend to lean on the high rail. As a broad conclusion, the ideal situation (i.e. the lowest forces, track structure degradation and costs) is achieved when uphill and downhill trains operate as closely as possible to the same speeds. The wrinkle is that an adjustment must be made to superelevation to compensate for the effects of drawbar and other vehicle / track forces.

The geometry car readout shown in Figure 1 plots loaded gauge, which is overlaid with an analysis of superelevation bandwidth — the full range of superelevations needed to achieve balanced forces for all of the trains over a particular segment of track. In the geometry car trace, several spikes and ripples appear, corresponding to locations of broken screw spikes (CP uses cut spikes in tangent sections of this timber tie track, and rolled plates with premium fasteners in sharp curves). Spikes that appear in sharp curves tend to correspond to areas that require superelevation adjustment due to the different speeds at which trains are operating, or adjustment to the powering or braking of the trains.

Looking at corridor fluidity, each of the traces shown in Figure 2 shows the progress of a train with time. This is predominantly a single-track operation, with segments of double track. Balancing the flow through this corridor comes down to balancing between the eastward and the westward operations. The use of distributed power and corresponding increase in velocity tends to improve the overall capacity in the corridor.

As a result of the investigation into the effects of distributed power, CP is running some new models (train makeups and distributed power configurations). These are primarily built around a 2-1-1 configuration (2 head-end locomotives, 1 mid-train and 1 pusher). Based on these models, CP has begun running 129-car coal trains, 142-car potash trains and has tested 168-car grain trains (with 5-locomotives).

Friction Management

CP's western corridor is the main focus of CP’s Total Friction Management^TM (TFM) initiative, a combined project between Canadian Pacific and Portec Rail. Looking at Figure 3, dark green areas correspond to territories where deployment is complete (i.e. top-of-rail (TOR) friction management has been rolled out in conjunction with gauge-face lubrication). Light green indicates areas where deployment is partially complete; yellow is new in 2009; orange is scheduled for 2010.

The CP Western Canada TFM initiative covers the mainline route west of Calgary — a total route mileage of about 900 miles. Implementation includes the addition of about 308 TOR application systems to the 17 that were already in place from an earlier pilot program. A curvature threshold of 4 to 5 degrees — the point at which steering saturates — was put in place for TOR coverage. The program focuses on territories where curves are particularly sharp, where rail wear and track degradation is particularly high.

PAGE 1 OF 3 | NEXT PAGE >