IIHS Issues First Ratings After New Frontal Crash Prevention Technologies Tests

Front crash prevention is part of a larger group of crash avoidance features spreading through the U.S. vehicle fleet. Marketed under various trade names, system capabilities vary by manufacturer and model, and most are offered as optional add-ons. In general, current front crash prevention systems fall into two categories: forward collision warning and front crash mitigation or prevention with autobrake.

Forward collision warning alerts a driver when the system detects that the vehicle is about to crash into the vehicle in front, but the system doesn’t slow down or stop the vehicle. Some forward collision warning systems are combined with an autobrake system to reduce vehicle speeds in a crash, but they aren’t designed to avoid the collision. Acura’s Collision Mitigation Brake System is an example.

Other autobrake systems can slow down or completely stop the car to avoid some front-to-rear crashes if its driver doesn’t brake or steer out of the way in response to a warning. Like the Acura system, these will reduce the speed of those crashes they can’t prevent. Cadillac’s Automatic Collision Preparation and Volvo’s Collision Warning with Full Auto Brake and Pedestrian Detection combined with City Safety are examples.

Another design difference involves whether the vehicle ahead is stopped or moving. All of the front crash prevention systems that earn a superior or advanced rating from IIHS are capable of braking for a stopped or slower -moving vehicle. Some other systems are designed to brake for a stopped car ahead only if sensors first detect the car moving before it stops. The BMW 3 series sedan is available with this type of system. It gets a basic rating for front crash prevention.

“The point of autobrake systems is to help inattentive drivers avoid rear-ending another car,” Zuby explains. “It’s clear that the ability to automatically brake for both stopped and moving vehicles prevents the most crashes.”

Test track evaluations

To gauge how autobrake systems from different manufacturers perform, the Institute conducted a series of five test runs at speeds of 12 and 25 mph on the track at the Vehicle Research Center in Ruckersville, Va. In each test, an engineer drove the vehicle toward a stationary target designed to simulate the back of a car. Sensors in the test vehicle monitored its lane position, speed, time to collision, braking and other data. The IIHS protocol is similar to the procedure the European New Car Assessment Programme uses to evaluate autobrake systems, which the group plans to begin rating in 2014.

The Institute awards as many as five points based on how much the systems slow the vehicle to avoid hitting the inflatable target or lessen the severity of the impact. In the case of an unavoidable collision, lowering the striking vehicle’s speed reduces the crash energy that vehicle structures and restraint systems have to manage. That reduces the amount of damage to both the striking and struck car and minimizes injuries to people traveling in them.

“We decided on 25 mph because development testing indicated that results at this speed were indicati ve of results at higher speeds — and because higher-speed tests would risk damaging the test vehicles,” Zuby says. “As such, we expect crash mitigation benefits at higher speeds as well.”

A vehicle must achieve 4 to 5 autobrake points to earn a superior rating and 1 to 3 points for an advanced rating. Vehicles get one additional point if they have a forward collision warning system that meets NHTSA criteria.

The highest-scoring cars and SUVs have autobrake and substantially reduce speeds in both the 12 and 25 mph tests. Most of these systems prevent the 12 mph collision.

Subaru’s EyeSight performed best. It helped the Legacy and Outback avoid hitting the target at both test speeds. Next best was Cadillac’s Automatic Collision Preparation. The system helped the ATS and SRX avoid hitting the target in the 12 mph test and reduced the ATS’s speed by 15 mph and the SRX’s speed by 19 mph in the 25 mph test.

“We want to help get the most effective systems in as many vehicles as soon as possible. That means a speed mitigation system like Subaru’s EyeSight that can prevent crashes at low and moderate speeds,” Zuby says. “At the same time, we want consumers to know that forward collision warning alone can help them avoid crashes, and it’s a feature that’s available on more models than autobrake.”

Besides the BMW 3 series, another midsize model advertised with autobrake also earns a basic rating. In tests of the Infiniti JX SUV, there was only minimal braking at 12 and 25 mph. The Toyota Prius v wagon, which claims to have autobrake, had minimal braking in IIHS tests and currently fails to meet NHTSA criteria for forward collision warning. It doesn’t qualify for an IIHS front crash prevention rating.

New criteria for highest safety accolade

The Institute introduced the TOP SAFETY PICK+ award last year to recognize models with the best crash protection. To qualify for the 2013 award, vehicles had to have good or acceptable protection in a new small overlap front crash test, in addition to good ratings for occupant protection in a moderate overlap front, side and roof strength test, plus good head restraints and seats for protection against neck injuries in rear impacts.

For 2014, vehicles also must have front crash prevention as standard or optional to qualify for the TOP SAFETY PICK+ accolade. Models with a basic, advanced or superior rating for front crash prevention are eligible to win. The Institute will award TOP SAFETY PICK to models with good ratings in 4 of 5 tests and good or acceptable in the fifth test. Winners of the 2014 awards will be announced in December.

Source: IIHS