Technology


Acceleration modulation Many of the electrified and mechanical rail systems in operation today are highly automated, designed to maximise all operational elements, and to improve the service experience while minimising cost. Most of us have


experienced a train, subway or airport rail system with the all too familiar rapid acceleration on departure, and deceleration on arrival. This


function is actually quite complex, with the need to replicate the acceleration condition with variations in track inclination, highly variable weight loads due to changes in onboard passenger volumes, plus track conditions, such as ice, rain, snow. Optimising the G forces during these


events is accomplished using a sophisticated accelerometer, which provides a feedback signal to the train’s main control system. In this way, we, as passengers, can at least know what to expect, regardless of the high level of variability that exists where these vehicles operate.


Alignment in repairs Most of the repair work performed on rail lines is accomplished using highly automated machinery, capable of removing damaged sections and completely rebuilding them in a single integrated procedure. Strict rules exist through regulatory


agencies as to the configuration of the rails to the surface they are mounted on, and to each other. Very slight errors in positioning can lead to repairs that are out of specification, and ultimately present a significant safety hazard and liability. To ensure proper orientation and


alignment, most alignment repair systems are equipped with both single and dual axis


LSOC Servo Inclinometer: The fluid damping of the servo mechanism absorbs vibrations within rail applications to improve reliability


significantly to their costs. The decision to take a rail section out inclinometers. These devices help rail owners and


the repair companies ensure that track conditions are optimised and in compliance once repairs are complete.


Rail line condition Although some situations exist where the need for rail repair work is obvious, many other conditions worthy of repair are more subtle. Ground subsidence due to track bed undermining, for example, or the warping of tracks due to excessive wear, can put sections of rail out of compliance with their rated load and speed schedules. In the United States, there are four


categories for rail systems that define how fast a train can run, and how much weight the rails can carry. If a section of track falls out of compliance, operators are compelled to reduce loads and speed, which can add


‘Many of the electrified and mechanical rail systems in operation today are highly automated’


of service is not taken lightly, as this can adversely affect schedules and car availability, rippling through the rail system and possibly putting time-sensitive cargo at risk. The industry has addressed these issues


by developing equipment to proactively inspect their rail systems and ensure compliance. This equipment includes wheeled vehicles that ride the system while collecting and logging critical data such as rail gauge, incline and offset. Incline and offset data is captured using highly sophisticated dual axis inclinometers, whose performance is optimised to allow these vehicles to travel at very high speeds, while still being able to pinpoint compliance problems to within just a few inches.


Moving forward The rail industry, like many others, has evolved over many years. Sensors have played a key role in improving rail travel reliability, affordability and safety. In particular, sophisticated inertial sensors are employed to address key operational and design challenges. Nevertheless, rail owners and operators continue to look to the sensor industry for novel solutions, as new challenges arise with every advance in rail system and equipment designs.


JESSE BONFELD is VP of business development for Sherborne Sensors


DECEMBER 2011 PAGE 37


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