During its Operation Safe Driver Week this summer, the Commercial Vehicle Safety Alliance (CVSA) found speeding as the top violation. During the safety blitz, officers pulled over 28,148 commercial vehicles, citing 1,690 commercial drivers for speeding and warning another 2,549.
That impacts overall road safety, of course, but also could cause disruptions for a fleet’s maintenance division. Exceeding recommended speeds takes a toll on the overall health of a truck, as fuel is brined faster and more inefficiently, and the brakes must work harder to slow momentum. That friction leads to excessive tire tread wear, as well.
These are just basic common-sense ramifications, but to get into the nitty gritty of driving too fast and too furious, we asked various trucking stakeholders to sound off on the specifics:
Joe Kay, Meritor's director of Engineering, Front Drivetrain, explained the physics of braking:
“The function of a brake is to convert kinetic energy into thermal energy (heat) then dissipate it into the atmosphere. The basic equation for energy is 1/2M V*2. The importance of showing the physics equation is the V- Velocity (speed) goes up by a square factor. For example, if an 80,000-lb. tractor trailer is traveling at 50 mph, the kinetic energy calculates to 6.7M Ft* lbs., and if the same vehicle is traveling at 60 mph, the kinetic energy is 9.6M Ft* lbs.—a significant increase in energy.
Because the energy requirement goes up by the square of the speed it means the amount of thermal energy (heat) also increases at an exponential rate. This example assumes the vehicle gross weight and the desired deceleration rate are the same.
Applying the brakes from higher rates of speed are likely to have effects on wear of pads, rotor, or drums, or tires. The life of a brake will depend on speed when the brakes are applied, the deceleration rate (emergency-type stop verse longer stop), the operating temperatures of the brake, condition of all the brakes on a vehicle, etc.”
Kay also offered some advice on rooting out possible habitual speeders, who could then be coached up to slow down:
“Most fleets will be able to detect driver abuse verse the normal or expected wear life. Operators that tend to abuse brakes usually have symptoms like 1) accelerated wear and 2) thermal (overheating) shows up as burned or scorched boots, seals, grease. It may also show up with blued color drums or rotors.”
Willie Reeves, maintenance manager at PacLease, Paccar’s truck leasing arm, echoed Kay’s sentiments on brake wear and tear, adding:
"Ultimately, speeding can cause a truck to have to come in for unscheduled preventive maintenance service, which drives up the cost of operating the truck. Having unscheduled maintenance can cause headaches for a maintenance facility due to the shop having to ensure they have the parts on hand and the proper technician available to perform the work.
Tire wear is another casualty. Tires generate heat, and increased speed causes more heat to build due to the load placed on the tire—especially if the trailer is loaded. Tires have a speed rating that can vary from 55 mph to 70 mph. Many drivers are not aware of their tire speed rating—it’s important to know.
What’s more, heavy braking can cause tires to become flat-spotted, which changes the shape of the tire. This can potentially cause a blowout, creating a safety hazard, requiring a service call, and delaying delivery. Even without a blowout, flat-spotting will require the tire to be replaced prematurely. It also means the shop will have to review the tire program it has in place with the customer."
The powertrain and aftertreatment also feel the affects of a driver’s need for speed. Reeves explained:
"Engines will run at a higher rpm rate to achieve higher speed. That builds up heat, reduces fuel economy, and adds more stress on the engine and its components. Regen cycles will also occur more frequently due to the excessive heat, causing the use of more diesel exhaust fluid. Overall truck health will be impacted as it will cost more to operate the unit due to more frequent PM cycles.
Uptime is affected due to the unit having to be scheduled for PMs more often. Many trucks run three to four PM cycles per year. With constant speeding events, those PM cycles can increase to four to six per year and additional road service calls could occur. All of this means a reduction in vehicle uptime."
So what is Reeves’ advice to get drivers to slow down and keep fleet operations running smoothly and according to schedule?
"It starts with communication and having a productive relationship between the shop, customer and driver. This will ensure the best overall health of the vehicle to prevent lost uptime and added maintenance costs.
For fleet managers, utilizing data from telematics devices can play an important role. Most telematics devices track data such as speeding, hard braking events, and engine overspeeds. Fleet managers can use this information as a coaching opportunity with their drivers."
While components such as tires are getting more expensive and harder to come by, Paul Pettit, VP of maintenance at third party logistics carrier Dart Transit, reminded that there are bigger things at stake than wear and tear:
"I believe the safety of everyone out on the road is more important than the damage done to the equipment, and reducing speed to prevent injuries is always the best way to go in my opinion.
Maintenance is also involved in repairs to any damaged equipment, and speeding can be a leading factor in increased accidents.
We have pre-determined pull points for brakes and tires, so we are pretty aggressive with when we are making changes. All of these will ideally be done at our PM interval, so speeding doesn’t have much impact on downtime or availability over regularly scheduled maintenance."
And to lighten all those lead foots, the Eagan, Minnesota-based fleet uses a mix of technology, training, and trust building, Pettit said:
Dart uses a tiered system for truck speeds based around tenure and safe miles driven. We use the vehicles’ programming to limit the speed the truck will go, and adjust the speeds when certain criteria are met. We also use some in-cab technology to alert drivers when they are speeding. That’s reinforced through our safety department by coaching on any speeding alerts we receive.
We have a few different speeds we allow our drivers to achieve over time; however, we don’t allow speeding over the posted speed limit, and most of our governed speeds are below the posted speeds in certain areas.
