Automatic Warning System for increased rail passenger safety


Train drivers on most European lines are informed of approaching warnings and cautions through the use of an AWS (Automatic Warning System). As the train reaches a certain point on the track a non-contact inductor sends a signal which is detected in the drivers cab. An audible or visual alarm then activates to alert the driver who then needs to acknowledge the signal otherwise the brakes are applied. Our client has an in-house design capability and required an experienced, reliable PCB manufacturing partner to review the designs and provide a strong, dependable supply chain of the fully populated boards to the exacting standards required for such an important part of the train system.

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The environment in which these PCB’s operate is challenging and has a high degree of variability. Large swings in ambient temperature range, dust and dirt ingress, varying humidity levels and high levels of vibration are some of the variables encountered. Hence we needed to ensure the design and manufacture of the PCB’s was to the standards required to give a long service life. Our engineering team considered the environmental, mechanical and electronic parameters to ensure the high degree of reliability required was met with the final production boards. This included the use of an acrylic conformal coating using a selective application process to protect the components from the harsh environment.



Upon review and approval of the design and manufacturing details, a prototype batch of units was produced for final test of the circuit functionality and suitability for the environment. On completion of these tests, the final design was signed-off by our client and a fully documented build pack was produced. The output of which was the series production of conformal coated PCB’s for both the audible and visual variants of the AWS units, compliant with rail standards including EN50155 “Railways Applications Electronic Equipment Used on Rolling Stock” and EN50121 “Railway applications - Electromagnetic compatibility,” to help ensure the safety of passengers, crew and the trains themselves.

This is an example of how May & Scofield's capabilities to deliver build to print PCB's could be utilized by other customers in a different application or industry.




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