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UMTRI-IIHS study: Easy-to-spot anchors boost tether use

February 26, 2014

If a vehicle’s tether anchors are easy to find, parents are more likely to use top tethers when installing a child restraint, according to a study performed by UMTRI for the Insurance Institute for Highway Safety.

This is most often the case in sedans. Most tether anchors in sedans are on the rear shelf, behind the back seat, where they are easy to see. In SUVs and minivans, parents usually have to search for the anchors because they are typically on the floor, middle or lower seat back, in the cargo area or on the ceiling.

Tethers are part of a child restraint attachment system called Lower Anchors and Tethers for Children, or LATCH. All forward-facing child restraints made since 1999 have a built-in top tether typically located just behind the upper back of the child restraint. Top tethers should be used with all forward-facing child restraints, whether they are secured by safety belts or with a vehicle's lower anchors.

Previous studies have established that parents only use top tethers with forward-facing child restraints about half the time despite the fact that passenger vehicles have had corresponding anchors to attach the straps for more than a decade.

UMTRI associate research scientist Kathleen Klinich led the current study.

“We also found room for improvement in the owners’ manual instructions for using the tether,” said Klinich. “Providing better directions for how to route different styles of tethers could help reduce errors.”  

In the study, researchers recruited 37 parents and specifically told them to use LATCH to install two different forward-facing child restraints in four different vehicles for a total of eight installations. The 16 vehicles used in the study had a range of tether anchor characteristics.

Parents used the top tether in 89 percent of the 294 forward-facing child restraint installations and attached the tether correctly 57 percent of the time. Because the instructions were designed to encourage tether use, the rate of tether installations was higher than recorded in field observations. Tether use rates improved from 83 percent to 95 percent after researchers in the study gave parents specific instructions on using LATCH and tethers halfway through their installations.

In sedans with tether anchors located on the rear shelf, 95 percent of parents used tethers, compared with 79 to 89 percent of parents when the anchors were located on the floor, ceiling or seat back. What's more, parents in the study were more likely to use tethers correctly when anchors were on the rear shelf or at the middle of the seat back than those located in other spots in the vehicle.

Additionally, the researchers noted that when vehicles had hooks for tying down cargo or other confusing hardware that could be mistaken for a tether anchor, the chances that parents would use and correctly install tethers were lower than in vehicles without such gear. This was most often the case in SUVs and minivans, while sedans were less likely to have confusing hardware. If parents did use top tethers in vehicles with confusing hardware, just 47 percent of the straps were attached correctly, compared with 70 percent of installations when there was no confusing hardware.

The study findings complement earlier UMTRI and IIHS research of the key vehicle factors that make lower LATCH anchors easier to use.

Read the full report.

Also see IIHS Status Report.