Over the years, Trainweigh have attended many trade shows and have showcased our AX Series of portable scales as well as our Force WIM (weighing in motion) systems. By doing so we have met many clients, suppliers and general public who have all been intrigued by what our products can do. However, there is always one question that comes up in nearly EVERY conversation.
“Why do you have to weigh trains?” It is very easy for us to answer that question…..SAFETY!!
We hear so much of train derailment but what causes a train to derail? There are a few well known factors that cause derailment, but most cases involve one crucial factor, poor weight distribution.
“Surely this doesn’t happen in this day and age?” This is usually the second question asked.
You often see trains going around bends on the track looking very much like the Leaning Tower of Pisa. At the same time, you possibly find yourself thinking “how does that stay on the track?!?” Through engineering marvels, the train is designed to stay on the track even whilst leaning in this nature. However, none of this is possible without the correct weight distribution of every component on that train’s carriage.
When a train reaches curves in the track the rail is higher on one side (this is called a cant).
A visual demonstration of a cant on a curved rail
Whilst travelling over this part of the rail the train leans into the curve making it look like the picture above. If there is a poor weight distribution, then any part of the train can eventually be derailed but not necessarily from tipping over.
Case Study
Whilst we were researching how we could develop our Trainweigh products to include Rail Safety Features we came across many reports from Rail Accident Investigation Branch (RAIB) involving a rail incident that occurred in the UK in 2020 at Wanstead Park, London.
In brief, the train, carrying a clay-like material, departed after having its wagons weighed whilst loading material. The total capacity of the wagons were not exceeded.
The train, travelling on its way at the recommended speed, came to a slight curvature in the track. The wheels on certain wagons exerted excessive force on the rail, tilted the rail causing the rail gauge (the distance between the two rails) to widen. This then caused the wagon’s wheels to fall into the four-foot (the area in-between the two rails) and the train subsequently derailed.
Rail gauge widening caused by a side-overloaded wagon
“But the train was weighed, and it wasn’t speeding! How did this happen??” I hear you ask! Correct, the trains wagons were weighed but only to a total capacity. The wagons did not exceed this capacity therefore were within the UK guidelines for travelling on UK rail.
When the wagons were investigated by RAIB, following the accident, this is what they found as per the report:
“The wagons were loaded at Barking using a 360° excavator with a weighing facility, working from the right-hand side of the train. This method of loading, and the nature of the clayey material involved, contributed to the payload in every wagon being off-set towards the right-hand side when the train left Barking on 23 January.
Wagon 3415 did not exceed the maximum gross vehicle weight, but the load was concentrated towards the rear right corner of the wagon. The load on the leading and trailing wheelsets on the trailing bogie weighed 26.4 tonnes and 25.95 tonnes respectively, both exceeding the 25.4 tonne RA10 limit.
In addition, the payload was off-set so that the two right- hand wheels on this bogie were carrying over 6 tonnes more than the left-hand wheels with a maximum wheel load of 14.9 tonnes, which can be compared to the 12.7 tonnes carried if the maximum permitted vehicle load is distributed equally between all wagon wheels.”
As you can see from the report excerpt, even though the wagons were weighed, the weight was NOT distributed correctly causing one side of the wagon to exert more force than usual on the rail. Along with poor track maintenance this essentially caused the gauge to widen and then the derailment occurred.
What is our solution?
You will also see from the report that this incident is not on its own. Over the past few years there have been a number of incidents with the exact same outcome. This is why after reading the report we went to the drawing board to design a system that could assist in combatting this issue, thus our DPS (Derailment Protection System) was created.
Our DPS watchdog being used with our AX400 Series bogie weigher
Our DPS monitoring watchdog is designed to not only take the total weight of each bogie, wagon and train but also shows side loadings, axle loadings and individual wheel loadings. In the particular case above, had the loading station had our watchdog installed, the DPS would have shown that the loadings on one side of wagon 3415 were overloaded and would have instantly alerted the operators and loading engineers that the wagon was NOT suitable to depart the loading station. The operators and loading engineers could then easily locate the offending area of the load and correct it instantly, saving millions of pounds in damages and potential loss of life and the legal proceedings that occur with any rail incident.
The report by RAIB on this incident is downloadable at https://www.gov.uk/raib-reports/report-12-2020-derailment-of-a-freight-train-near-wanstead-park
You can view our Trainweigh products at www.weighbridgeservices.com/trainweigh
A bright new look for a brighter future in rail weighing
Following the integration of both our Weighbridge Services Ltd and Trainweigh products, we have now also brought our two websites together at weighbridgeservices.com and weighbridgeservices.com/trainweigh respectively.
Our Trainweigh products are also now more easily identifiable for whatever type of industry you work in whether it be freight or depots and workshops. Each of these industry pages make it quick and simple to identify what type of Trainweigh products are suitable for your specific application.
Visit our new look website today and see what Weighbridge Services Ltd can offer you!
