Pulsing Back-of-Trailer Lamps Aim to Prevent Crashes

I don’t think I’ve seen so much attention to rear trailer visibility since conspicuity tape became mandatory 20 years ago. This time, however, it’s not a controversial mandate, but optional additional rear trailer and body lighting that pulses when the brakes are activated.

Federal Motor Carrier Safety Regulations require all exterior lamps (both required lamps and any additional lamps) to be steady-burning, except for turn signal lamps, hazard warning signal lamps, school bus warning lamps, amber warning lamps or flashing warning lamps on tow trucks and CMVs transporting oversized loads, and warning lamps on emergency and service vehicles authorized by state or local authorities.

But Oklahoma-based tank truck carrier Groendyke Transport decided it would bend those rules to tackle the problem it faced from distracted drivers hitting them from behind. The idea of the flashing amber light came from the advance warning signals that precede some traffic signals at rural intersections. They are used to warn drivers the traffic signal is about to change. 

In road testing, drivers began pulling the specially equipped trailers almost immediately reported seeing changes in the behavior of people driving behind them. When the brake lights came on (and the strobe began blinking), car drivers began making lane changes sooner to get around the truck, the drivers said. The amber strobe was making people notice that the brake lights were on.

Groendyke tracked two groups of trucks for 90 million miles over 30 months, from January 2015 to July 2017. One group was fitted with the strobes, the other without. The data revealed that the flashing amber light that blinked when the drivers applied the brakes reduced rear-end collisions by almost 34%.

However, during the testing, the company received somewhere in the neighborhood of 40-50 violations for using the technically illegal additional brake light. So in April 2018, after gathering and correlating all the data collected over the course of the trials, Groendyke submitted a formal petition to the Federal Motor Carrier Safety Administration, which was granted about a year later in April of 2019.

Groendyke is a member of the National Tank Truck Carriers, which was supportive of its exemption application, and filed for an exemption that would allow all tank truck carriers to install similar warning lights. That exemption was granted last October, a limited five-year exemption to allow motor carriers operating tank trailers to install a red or amber brake-activated pulsating lamp in the upper center position or in an upper dual outboard position on the rear of the trailers.

Lighting manufacturers such as Grote Industries and Peterson Manufacturing have developed products specifically for this application.

Grote unveiled its Auxiliary Strobe & Stop Lamp late last year. The company said it designed the lamp specifically for this application rather than re-packaging an existing product. Braking initiates a sequence of five amber flashes in four seconds followed by a solid red burn. This light sequence exceeds the attention-getting capability of standard solid-burn brake lights, according to Grote, while not overwhelming following drivers with long periods of strobing.

Peterson’s LED Auxiliary Brake-Strobe Light and Harness System is specifically designed to meet the specifications of the FMCSA’s 49 CFR 393.25 five-year exemption for tanker fleets. Tank fleets can now install Peterson harness components and Peterson LumenX LED 10-diode strobe light.

Beyond Tankers

If the technology works for tankers, why not for other types of trailers and even truck bodies?

As far back as 2009, the National Highway Transportation Safety Administration was doing research into whether pulsing, rather than steady, brake lamps would help prevent rear-end collisions. It reported that although data available was sparse, the “data do suggest that flashing with increased brightness may be effective in reducing the incidence of long off-road glances,” and that “drivers exposed to the flashing with increased brightness were more likely to brake in response as compared with conventional, steady brake level signals.”

In addition, the Federal Motor Carrier Safety Administration found that data between 2010 and 2016 revealed that large trucks are three times more likely to be involved in rear-end accidents resulting in fatalities, according to Peterson.

Late last year, FMCSA gave Grote a five-year exemption to take the technology beyond tankers, to allow motor carriers operating trailers and van body trucks to install amber brake-activated pulsating warning lamps on the rear of trailers and van body trucks in addition to the steady-burning brake lamps required by the Federal Motor Carrier Safety Regulations. Grote asked for requested allowance to use:

• an upper pair of brake-activated warning lamps centered about the centerline of the trailer
• a single brake-activated warning lamp centrally located on or below the rear sill collinear with the stop/tail/turn lamps
• a lower pair of brake-activated warning lamps centered about the centerline of the trailer located on or below the rear sill; or
• a combination of an upper pair of brake-activated warning as described in combination with either of the lower brake-activated warning lamps.

More recent exemption requests, which at this time are still under consideration, want to take the pulsing light concept to additional types of trailers and bodies.

Waste Management asked for an exemption to allow all of its 106 operating companies to replace the high-mounted brake lights on their fleets of heavy-duty refuse and support trucks with red or amber brake-activated pulsating lamps positioned in the upper center position, or in an upper dual outboard position, in addition to the steady burning brake lamps. Currently, WM has installed an additional steady burning brake lamp (not required), but proposed changing out this “additional steady burning brake lamp” with a brake-activated “pulsating lamp.”

Intellistop petitioned FMCSA for an exemption to allow motor carriers to operate all commercial motor vehicles, including flatbed trailers and straight trucks, equipped with Intellistop's module, which pulses the rear clearance, identification and brake lamps from a lower level lighting intensity to a higher-level lighting intensity four times in two seconds.

Unlike the exemptions allowing for additional lighting, Intellistop wants to use a system that would combine the flashing or pulsing concept with existing brake lights. It asked to incorporate the Intellistop module with the preexisting brake, clearance, and I.D. lamps, creating a pulsing cycle while maintaining the steady burning red brake lamps as required by the FMCSRs. During the four pulses, the light does not go out, and after the four pulses the lamp finishes at full burn until the driver releases their foot from the brake pedal. The petition pointed out that NHTSA has previously interpreted that clearance lamps and I.D. lamps may have dual functionality as long as the primary function of that lamp is maintained.

Drawing attention to the actions of trailers will increase operator safety and minimize rear-end collisions, meaning less equipment and freight damage, less downtime, and fewer delayed shipments. “Additional functionality for auxiliary lights will cut down on accidents, property damage, and make our highways safer," said Mark Blackford, Grote director of national fleet sales.

For fleet managers, that means a better safety record, fewer CSA headaches, more money saved, and most importantly, a safer road for everyone.