RUNNING KEEP IT

In August, we take a closer look at special trackwork and the maintenance technology that it requires to allow freight and passenger trains to operate without incident. Special trackwork, meaning turnouts, sidings, and crossovers, among others, are feats of engineering that make it possible for trains to move in the right direction. And the type of special trackwork needed is dependent on several factors. For example, the needs of a speci c railroad and the surrounding topography dictate where sidings can be built.

Sidings are tracks that split from the main line to allow trains to serve industries, access yards or move entire trains to a “passing siding” to allow a higher priority train to pass. Crossovers are a series of switches that allow trains to move from one parallel main line track to the other. Simply put, the purpose of special trackwork is to allow a train to change direction and take a di erent route onto another track. e switch and the frog are two important parts of a turnout. While the switch is what allows a train to move from one track to another in a turnout, the frog is what guides the ange of the wheel through the crossing. e switch rails move at the switch point by way of the switching rod. Early versions of the switching rod were controlled by manual labor via a point person. Today, there are vendors who have developed point machines to handle this job. A track point machine has the ability to function remotely.

A turnout starts with stock rails, which are the rails that lay straight when the switch rails are in a closed position. Inside of the stock rails are the switch rails, or sometimes called point blades, and these are the movable rails in a turnout. ese switch rails, controlled by a switching rod, guide the wheels to stay on the current route or to turn onto another track. A shorter switch track section in a turnout allows for repairs and replacement of the switch track without having to replace the entire turnout.

A vendor that has o ers a switch machine and works to develop a system approach to special trackwork is voestalpine Railway Systems Nortrak LLC. Tahira Dhanji, Senior Vice President of Strategy & Corporate Development told RT&S that “the bene ts of the systems approach go beyond reduced wheel impact loads and reduced noise – increasing service life, availability, and reliability, while reducing maintenance.”

Combined with more than four hundred years of railway design experience, Nortrak’s design expertise in concrete,

By Jennifer McLawhorn, Managing Editor

hydraulics, plastics, metallurgy, asset monitoring, and electrical systems deliver a “multi-disciplinary approach to railroading.” By integrating concrete crossties and turnout ties, switch drives, fastening systems, special trackwork performance, and asset performance, Nortrak has an extensive system for rail operations which includes a variety of freight and passenger operations.

In its o ering for a switch machine, Nortrak has developed its UNISTAR HR switch machine. It provides an array of bene ts, some of which include complete control of the switch points at a turnout and the ability to monitor each throw, alerting operators of deviations in trends that indicate maintenance requirements to prevent a failure.

In addition, the UNISTAR HR switch machine is easy to install due to its weight of 165 pounds. It also has a smaller footprint that provides versatility to mount outside of gauge, on concrete, wood, or hollow steel ties, in gauge, or on tunnel walls. ere are no additional modi cations to the signal system, and the same UNISTAR HR switch machine can control the movement and locking of Nortrak’s thick web moveable point frog (MPF) on turnouts as large as a #24. is system approach from Nortrak can reduce installation costs as well as the upgrading of a turnout to a thick web MPF. Once a switch machine such as Nortrak’s o ering has changed the direction of the ow of tra c, a passing train can continue to run smoothly through the rest of the turnout.

Along the rest of the turnout, the switch rails meet and form a small gap. e gap exists between the switch rails and the vee section to allow for a train to cross the junction without hitting another track. e switch rails extend into wing rails past the frog, and the wing rails support the wheels through the frog as the train moves onto the diverting track. Check rails, or guard rails, exist on the inside of the stock rails to help guide the wheels onto the correct track. While the switch rails are the only moving components of a turnout, if a guard rail does not function exactly as intended, the wheel of a passing train can hit the frog and derail.

Seemingly a simple design, special trackwork such as crossovers and sidings require a great deal of maintenance. Each component must be designed and aligned correctly to function as it should. Even with the addition of remote-controlled point machines such as Nortrak’s o ering, maintaining special trackwork is a technical and serious undertaking.