Will NHTSA’s Distracted Driving Guidelines Cripple Navigation Displays?

Sunday, March 25, 2012

Will NHTSA’s Distracted Driving Guidelines Cripple Navigation Displays?

Last month the Dept. of Transportation, through NHTSA, issued proposed guidelines on drivers' use of electronic devices that could distract them from driving. Wayne Cunningham, an automotive writer for CNet, has been mining the 177 page document and he's uncovered regulations that would effectively cripple navigation systems as we know them and also reduce the amount of information a car's systems can display to a driver at any one time.

Section V.5 of the Visual-Manual NHTSA Driver Distraction Guidelines for In-Vehicle Electronic Devices is devoted to graphical displays, including photographs and video, and NHTSA frowns on what they call "dynamic" displays. The guidelines call for static or "near-static" displays. Near-static would conform to NHTSA's intention of prohibiting any act that would take up more than 2 continuous seconds of a driver's attention. Obviously a static map on a navigation system would be of little practical value, compared to how drivers use today's nav systems. A "near-static" display that updates in 2 second increments would be of little value at intersections and changes in direction. Lest you think this is an alarmist reading of a harmless regulation, the guidelines are very clear that their intent is to cripple dynamic navigation systems that show your car's position on a moving map, or alternatively, a moving car on a fixed map.

V.5.b Dynamic map displays. The display of either static or quasi-static maps (quasi-static maps are static maps that are updated frequently, perhaps as often as every few seconds, but are not continuously moving) for the purpose of providing driving directions is acceptable. Dynamic, continuously-moving maps are not recommended. (emphasis added)

At 30 MPH you're traveling 44 feet per second. A navigation system that only updates every 2 seconds would be functionally useless in most driving situations. You'd be past your turns and destination before the system could update itself. None of these guidelines, by the way, were arrived at after actually measuring how using navigation systems could possibly distract drivers. Instead they are based on the agency's general testing that shows that tasks requiring 2 seconds of continuous attention are distracting, as are discontinuous tasks that in total take up 12 seconds or more of your attention.

A system that does not update continuously would be more distracting because drivers would spend more time looking at the nav screen. When a display changes continuously, there's less need to check it frequently.

Another guideline Cunningham discovered that could change the way cars work is how text can be displayed as well as entered.

V.5.g Reading more than 30 characters (not counting punctuation marks, counting each number, no matter how many digits it contains, as one character, and counting units such as mph as just one character) of visually presented text.

Way more than 30 characters.

Cunningham points out that a standard satellite radio display of a station, show and song title can easily exceed 30 characters. The guidelines also prohibit the use of scrolling text – that would be too dynamic.

V.5.e Automatically scrolling text. The display of continuously moving text is not recommended. The visual presentation of limited amounts of static or quasi-static text is acceptable.

You also wouldn't be able to enter an address into your nav system while driving, unless the address is fewer than six characters total.

V.5.f Manual text entry. A driver should not enter more than six button or key presses during a single task. This would include drafting text messages and keyboard-based text entry.

It seems to me that another of the guidelines, one concerning obstructed vision, might prohibit heads-up displays.

V.1 No Obstruction of View.

V.1.a No part of the physical device should, when mounted in the manner intended by the manufacturer, obstruct a driver's field of view.

I'm not sure if the HUD qualifies as a "physical device". It does incorporate a plastic film in the windshield made by DuPont. Though the HUD doesn't obstruct the driver's view in any manner that would affect safety, it does, technically, obstruct the driver's field of view, and if enacted those guidelines will be the law.

These guidelines are meant to address changing in-car "infotainment" technologies. Come to think of it, the guideline about not pressing more than six buttons during a single task makes me think that this would regulate perhaps the oldest of infotainment technologies, the pushbutton radio.