Are Electronic Brake Performance Monitoring Systems (EBPMS) the most cost-effective and efficient way of testing your trailer brakes?

Overview

With EBPMS becoming the standard method for assessing trailer brake performance within the Transport and Logistics industry, knowledge on how to understand the results remains low.

History of brake testing & introduction of EBPMS

Systematic testing of vehicles’ brakes has been around since the 1920s when the Detroit Police Department determined the number of feet required to stop a moving vehicle. If the braking distance was within the required limit, the Police Officer issued the driver with a pass certificate, which would be dated and displayed in the vehicle’s windscreen, much like the old car tax disc.

In the 1970s roller brake testing (RBT) was introduced in the UK. A roller brake tester is a method of allowing the dynamic assessment of the braking system of a vehicle, whilst the vehicle itself is stationary. It subsequently became mandatory to be tested at least 4 times per year for HGVs or trailers. The vehicle must be loaded for a brake test - ideally to at least 65% of its total maximum weight.

In the 21st century, EBPMS was introduced to dynamically test a vehicle’s brakes while in use.

How does EBPMS work?

EBPMS is a system that enables the braking performance of a commercial vehicle to be monitored and recorded during everyday operations under a variety of operating conditions. EBPMS autonomously collects braking event data during every braking event, and analyses the data over time to produce a braking performance value. While each EBPMS system works slightly differently, the DVSA has developed an industry standard specification which they have been developed to.

From April 2025, there will be an expectation that a laden RBT or EBPMS will be the only accepted methods to assess brake performance, with an RBT only required during MOT.

EBPMS vs. RBT results and interpretation?

In addition to the cost of roller brake tests (starting from ~￡12 per axle); and downtime to transport the vehicle to the site of the test, load it and unload it for the test; fleet operators have experienced significant challenges in fully understanding their RBT results.?

At a first glance this RBT above looks positive as the overall result is passed. However hidden in the details there are three factors of concern from this test:

• Insufficient axle load – For a brake test to be meaningful, each axle should be loaded to a minimum of 50-65% of the designed axle weights. Here the trailer was loaded to 51% of its total capacity. However this was not spread equally across the axles, which led to insufficient weight on axle 2 and 3.?
• Pass on locks – Testing a vehicle or trailer unloaded will lead to less braking force being exerted, the brakes locking earlier than they should, and a false positive test result which gives no indication of whether the vehicle will be able to stop safely when fully loaded.
• Dangerous imbalance – Any imbalance in the brakes on either side of an axle could lead to the vehicle pulling to one side under heavy braking and potential failure in emergency braking situations. It is recommended that any imbalances over 10% are investigated (as seen on axle 3),? and brakes adjusted to address the imbalance. However as the vehicle passed on locks it did not cause the overall test to fail.

As EBPMS monitors trailer brake performance out on the road, rather than in test conditions, the exceptions which appear under a roller brake test conditions are not replicated in real life and so can cause confusion. There are different key factors to look out for when analysing results from an EBPMS Report:

• Pass on locks - If a vehicle has passed its RBT on locks only, this does not indicate that the brakes are performing well and it could be shown as failing on EBPMS.?
• Score level ?- On some vehicles, calculated EBPMS can be higher than the corresponding RBT, up to 20%. Therefore for a vehicle with a result of 50% on EBPMS, it should not be assumed that it would score 50% on RBT.
• Impact of retarder - If the truck is equipped with a retarder this will artificially improve the brake rate reported for the trailer within the convoy.?
• Parking and secondary brakes - These can not be tested via EBPMS and instead a visual inspection is suggested alongside EBPMS.

These factors can lead to some operators either discarding EBPMS results, as they are not confident in them, or deliberately ignoring them, as a RBT passing on locks is sufficient to get the vehicle back out on the road in their eyes.

Conclusion

EBPMS offers many safety benefits to fleet operators, providing them with real-time insight into their vehicles rather than having to wait for their planned maintenance inspections to identify any issues. There are further cost and productivity benefits delivered through reduced downtime. However, results need to be carefully explained and considered independently from previous RBTs.

Are you paying high costs for brake testing or experiencing downtime due to brake testing requirements? Please reach out to us at MICHELIN Connected Fleet so that we can help you improve your fleet's costs and productivity.