Study shows USA child seat installation ease using LATCH

The IIHS has compared different vehicle makes fitted with the LATCH child seat installation system for ease of use by consumers.

Similar to ISOFIX in the European market, LATCH (Lower Anchors and Tethers for Children) is a system that uses hardware which is already installed in the car for fixing child safety seats rather than using the seat belts alone.

What is the difference between ISOFIX and LATCH?

The European ISOFIX, US LATCH and Canadian UAS systems are similar in their technology and applications but have some essential differences in terms of set-up, conformance to standards, operation and performance. Seats designed for a particular market should only be used in that market on vehicles that have corresponding hardware fitted to them. LATCH based seats may fit in ISOFIX equipped cars but are not designed to operate correctly in that environment.

In comparing ISOFIX and LATCH, a study performed by the United Nations Economic Commission for Europe (UNECE) to evaluate LATCH for European markets, showed that rigid ISOFIX results were superior to LATCH in all measured criteria during tests performed on a range of seats. The UNECE therefore continued its support for ISOFIX in the European market. For the full study, read the UNECE’s “Side impact and ease of use comparison between ISOFIX and LATCH“.

IIHS ease of use testing

The Insurance Institute for Highway Safety (IIHS) is the main vehicle safety evaluation body in the USA, similar to the new car assessment programmes in the rest of the world (NCAP). The organisation has recently introduced new LATCH ratings which will serve as a resource for families looking for a vehicle that makes it easy to transport their children safely. They also are intended to encourage vehicle manufacturers to pay attention to this equipment and make improvements.

Properly installed, age-appropriate child restraints provide considerably more protection for children in crashes than safety belts alone. However, observational studies have found that parents often fail to secure them tightly or make other installation mistakes.

Installing a child seat base using the US LATCH systemLATCH is intended to make it easier to install a child seat properly and reduce the human error factor during installation since child restraints installed with LATCH, rather than with vehicle safety belts, are more likely to be installed correctly, according to the IIHS research.

However, not every vehicle is created equally and the LATCH hardware is better in some than in others. Parents are more likely to install the seat correctly when the LATCH hardware meets certain key ease-of-use criteria.

“LATCH is meant to simplify child seat installations, but it doesn’t always succeed,” says Jessica Jermakian, an IIHS senior research scientist. “Parents often struggle to locate the anchors in the vehicle or find it difficult to attach the seats to them. We believe fixing these problems will make the task less frustrating for parents and increase the likelihood that children will ride in properly installed seats.”

The comprehensive tests performed by the IIHS showed that only 3 vehicles out of more than 100 they evaluated have hardware that earns a good rating for ease of use, while more than half have hardware that is poor or marginal.

Test Criteria

On the LATCH system, the lower anchors are located where the seatback meets the bottom seat cushion, an area known as the seat bight. Attachments at the bottom of the child restraint connect to these. The top tether connects the top of the child seat to an anchor located on the vehicle’s rear shelf, seatback, floor, cargo area or ceiling. This top tether is one of the key differences from ISOFIX, which uses a different method of preventing seat tilt.

Child restraints can be installed with lower anchors or safety belts. A top tether should be used with every forward facing child restraint, whether it is secured using the safety belt or using the lower anchors.

In the new ratings system, vehicle LATCH hardware is rated good if it meets the following criteria:

* The lower anchors are no more than 3/4 inch deep in the seat bight.
* The lower anchors are easy to manoeuvre around. This is defined as having a clearance angle greater than 54 degrees.
* The force required to attach a standard tool to the lower anchors is less than 40 pounds.
* Tether anchors are on the vehicle’s rear deck or on the top 85 percent of the seatback. They shouldn’t be at the very bottom of the seatback, under the seat, on the ceiling or on the floor.
* The area where the tether anchor is found doesn’t have any other hardware that could be confused with it. If other hardware is present, then the tether anchor must have a clear label located within 3 inches of it.

Under federal regulations, most vehicles must have at least two rear seating positions with full LATCH hardware and a third with at least a tether anchor. The IIHS ratings are based on the best two LATCH positions available in the vehicle’s second row.

To earn a good rating, two LATCH positions must meet all five criteria, and a third tether anchor also must be easy to use. For an acceptable rating, two LATCH positions must each meet at least 2 of the 3 requirements for lower anchors and at least 1 of the 2 tether anchor requirements. If either position meets neither of the tether anchor requirements or meets only one of the lower anchor requirements, then the vehicle is marginal. If even fewer criteria are met, the vehicle is poor.

The ratings measure ease of use only. A correct installation in a vehicle with poor LATCH is just as safe as a correct installation in a vehicle with good LATCH. The same is true for an installation with a vehicle safety belt: If it’s done correctly — including attaching the tether in the case of a forward-facing restraint — the child will be just as safe as with an installation using lower anchors.

Rating results

Of 102 current models that IIHS has rated for LATCH, the three good ones are the BMW 5 series, a large luxury car; the Mercedes-Benz GL-Class, a large SUV; and the Volkswagen Passat, a midsize car. Of the rest, 44 are acceptable, 45 are marginal, and 10 are poor.

The poor-rated vehicles run the gamut of vehicle types from minicars to large pickups. Most glaring is the Toyota Sienna. As a minivan, it’s commonly bought to ferry children.

The IIHS LATCH online ratings information helps consumers understand exactly why a vehicle gets the rating it does. A diagramme for each vehicle shows the location of all LATCH-equipped seating positions and which criteria those positions meet and which they miss. The location of extra tether anchors, for use with restraints attached with vehicle safety belts, is also shown.

In some cases, centre seating positions don’t have their own lower anchors, but manufacturers allow anchors to be “borrowed” from adjacent positions. The rating diagrammes show when such borrowing is allowed by the vehicle manufacturer.

“Even if you’re not in the market for a new vehicle, our ratings can be a helpful source of information about a vehicle you already own,” Jermakian says. “We’re essentially providing you with a map of where child seats can be installed most easily in your vehicle, including the specific hardware available for each seating position.”

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