Collision warning systems keep tabs on how far you are from the vehicle in front using radar, which passes through fog and smoke.
Time is one of the biggest factors when it comes to avoiding collisions. Under even minimally favorable road conditions, it might be all you need to keep safe, provided your vehicle is in working order.
So how fast is your reaction time? According to David Pierson, sales manager for the Vehicle Solutions Business Unit at Eaton Corp., racecar drivers may react to a dangerous situation in about half a second, but truck drivers typically take about 1.5 seconds.
Even if your reaction time is faster, you can still travel a long way in the blink of an eye – at 60 mph, 120 feet in 1.5 seconds.
That 1.5 seconds is plenty of time if a driver is rolling along with traffic and maintaining a good following distance. A collision warning system is designed to ensure that you always have at least that much time to react. They make up for the one thing that can defeat even the best driver – a momentary lack of awareness. As Pierson suggests, a driver might be pulling a sandwich out of a cooler, tuning the radio, or even doing his job by scanning the mirrors for trouble to the side or rear when something that spells disaster happens just ahead.
“Scanning the mirrors takes two seconds, and that means you travel 170 feet without looking at the road,” he says. That’s at 58 mph. You can multiply your speed in mph by 1.47 to get the distance you’re traveling in feet each second, in case you want to consider some other examples.
As Delphi Automotive’s Active Safety Start Center Manager Michael Ray says, “The system forces a distracted driver to pay attention to what’s in front of him.” Delphi describes its system as “a collision warning and headway alert.” It is actually composed of this and optional subsystems that include the forward collision warning/headway alert system, a lane-departure warning system, and a blind spot warning system, all of which are integrated, connected to the same controller, which reduces the cost.
Collision warning systems typically offer visual and audible messages so you don’t have to be looking at them to become alerted. This lets them help you without compromising your view of the road.
One of the most impressive aspects of these systems is the intelligence they add to basic radar, enabling them to fulfill one of the largest requirements the engineers design into them: the avoidance of nuisance warnings. Pierson says Eaton’s radar operates at a frequency that’s 60 MHz (mega-hertz) away from police radar. This way, the system won’t become confused and give you a false warning when Smokey is taking pictures of you.
Both systems combine a radar unit, a processor and a driver display. Their intelligence also allows them to be particularly smart about catching every dangerous situation. They incorporate not just radar receivers but also speed sensors and microprocessors, which are normally mounted, as in the case of the system made by Delphi Automotive, separately from the radar unit, well inside the cab.
Why is avoiding useless warnings so important? For the same reason the DOT should remove construction zone signs consistently once the work has stopped: People ignore inaccurate sources of information even when they know the source may sometimes be correct. As you might imagine, engineers have found that drivers will react negatively to a system that constantly bothers them when they are driving safely. In fact, they won’t just fail to pay attention to it, they will turn it off or, if that’s not possible, deliberately disable it.
By having enough of the right information and making sense of it, these systems manage to warn you only under critical conditions. They measure the distance of the vehicle ahead at frequent intervals. They also incorporate knowledge of the passage of time and some math. They combine those with an mph input from the vehicle’s speed sensor.
The systems calculate not just how far you are from the vehicle ahead, but how many seconds you are behind it, which depends on both distance and speed. Pierson says the Eaton VORAD system can be adjusted to give you a constant 2 1/4 to 3 1/4 seconds following time.
The systems also incorporate the closing speed, a basic capability of radar that has always helped operators to differentiate between an airplane or missile and a stationary object. If you are going 60 and the vehicle in front has slowed to 40, radar will catch the change and warn you while there is still time to do something about the situation. Of course, safe following times are shorter when both vehicles are cruising at the same speed. You need a lot more time and distance to react to a stopped vehicle than one that’s moving almost as fast as you are.
What you’ll see and hear
Audible signals that indicate just how much trouble you’re in allow you to be aware of what’s happening ahead even if you’re looking to the side, to the rear or at something in the cab. LEDs are also provided to give you a visual signal that is a little less annoying and shows up earlier. It’s just one of the ways these systems are designed to avoid annoying you unless you really need to know about something dangerous.
Pierson says the Eaton VORAD EVT-300 will not begin to react unless you are within 350 feet of the vehicle ahead. It first gives you a chance to react by lighting two lights when you are three seconds behind that vehicle. At two seconds, the lights will still be on, and, if you are closing in, a tone or “blip” will be added. However, at that time interval, the tone will not come on when the vehicle ahead is accelerating away from you.
When one second of following time is reached, you get a third light as well as an additional blip. Within a half second, you’ll get a continuous tone whether you are closing or the other vehicle is pulling away. The continuous tone is based on a simple truth: at this interval, it’s really time to back off because you won’t even be able to see taillights, according to Pierson.
The system is particularly aware of closing speed, and if you are traveling 20 percent faster than the vehicle in front of you, and in the range of 220 feet behind it, you’ll get what Pierson describes as a “triple tone of higher intensity.”
“You can’t stop an 80,000-pound truck in 220 feet,” he says. “This provides the opportunity to slow down and lessen the severity of a potential crash, as well as the time to decide whether or not there is an escape route. With the warning, you can figure out what to do much sooner.”
The Delphi system, according to Ray, first reacts when your speed and difference in speed combined with the following distance indicates potential danger. The signals consist of a colored lamp and a tone that Ray describes as a “ding.” As you get closer and closer to the vehicle ahead, the tones increase in frequency. Eventually, you’ll get “a collision warning event,” which means you’re in a truly dangerous situation. A typical example of what would cause this would be someone (possibly a four-wheeler) cutting in front of you at a close interval and then rapidly beginning to slow. You get what Ray describes as a distinctive “two-tone warble.” At the same time, the warning light begins flashing more frequently.
However, Ray says, “We want the driver to respond from hearing the warning, not from looking at the display.” Thus the tone is loud enough and distinctive enough to “force a distracted driver to pay attention to what’s happening.”
Once you mount a radar unit on the front of a truck and combine it with a speed sensor, you can do more with it than just warn the driver of trouble. One reason drivers tailgate is that they set the cruise control and then find somebody in front of them cruising at just slightly below their speed setting. Who wants to reset the cruise every two minutes?
Delphi’s Smart Cruise takes care of that job. Eaton calls their similar system Active Cruise Control.
“It integrates with the engine software,” Pierson says. “If you’re doing 60 and you come upon someone doing 58 mph, it will slow you and hold the same following distance.” The time (and as a result the distance) will be adjusted from a following time of 2 1/4 to 3 1/4 seconds so it’s appropriate for the speed. It communicates with the engine and transmission over an SAE J1979 link and can even downshift an automated transmission and use the engine brake to control your speed. If the other vehicle moves away or you move to an open lane, the cruise control brings you back up to the original setting.
Both Eaton and Delphi also make a side blind spot warning system for the right side of the truck. The Delphi system also has a lane-departure-warning subsystem available. This can follow even faded lane markings. When you begin to stray out of your lane without turning on the directional, it lets you know about it.
Both side blind spot warning systems are connected to the turn-signal system. This way, the system can ignore a vehicle riding next to you unless you are obviously turning toward it, a clear indication that you don’t realize it’s there. By interfacing the system with the turn signal, nearly all false warnings can be avoided.
Ray says the Delphi blind spot and lane departure warning systems were originally developed for the premium automotive market – a large market that allowed huge development costs. They were then reprogrammed to provide warning strategies ideal for heavy trucks.
Pierson says the Eaton VORAD version will illuminate a light to warn you something is there but keeps the audible signal off unless you flip on the turn signal. “The side sensor has a 10-foot range,” he says. “It covers one lane and has a 100-degree field of view.”
“The blind spot next to and in front of the door by the front fender is the reason for the window in the door,” Ray says. “But if the driver is busy, he doesn’t always look. Most drivers will admit they’ve made an error of that type.”
Pierson says, “The drivers we’ve interviewed talk about the side sensor as an additional benefit. It’s good for peace of mind.”
A new system
Eaton recently introduced a new version of its system called the VS-400. The radar unit is only about 25 percent of the size of the EVT-300 and uses a 77 GHz signal rather than 24.750 GHz, which gives it more range. It can see up to about 650 feet. It displays everything in one place, forming what Pierson calls “a collision and safety system in one display. Drivers were getting beeps and tones from all over. We tried to redesign it so the driver would look in one area of concern.”
It was developed as part of the Integrated Vehicle Based Safety Systems Initiative of the National Highway Traffic Safety Administration and includes integrated lane tracking capability. “Because of the [NHTSA] program, it’s more intelligent and intuitive,” Pierson says. It also includes a training program that reads out through an LED on the front of the display.
Some fleets use a recording function Eaton offers to train drivers in following at a safe distance.
Both systems are available as OEM factory installations, but if you’re an owner-operator with an existing vehicle, you can purchase one in the aftermarket and install it yourself. Pierson says the VS-400 is actually easier to install than the EVT-300. The earlier design requires a diagnostic tool to set it up. In general, “The installation manual, available through www.roadranger.com as a download, should tell you how to do it,” Pierson says. “The system needs to be plugged into the J1939 communications link, but a dealer should know how to do it and might be willing to give you some guidance.”
Ray says of the Delphi system, “We tried to make installation simpler. There are just four wires to connect the power and ground and to connect to the 1708 serial data bus. Beyond that, it’s easy – just plug it in and it’s working for you. The controller must be inside the truck and can be placed under the seat or dash at any angle. The harness will reach to the back of the sleeper cab, giving you plenty of flexibility in locating the controller.”
The harness plugs to the radar units and driver display and all the connectors are unique so you can’t hook it up wrong. Mounting brackets are included, and anybody with basic technical experience in a fleet maintenance department should be able to handle the job.
But Delphi’s Paul Martindale, Active Safety marketing manager, still recommends that you have a dealer service department do it. Labor time will be four hours maximum because of the job’s simplicity.
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