The businesses and individuals who publish or promote bad driving advice that they themselves have received from bodies that should be trustworthy on this crucial subject can hardly be blamed for regurgitating it. But the state governments that so typically publish very poor or even dangerous advice in their state drivers manuals truly should know better …. If only!
In this instance, it is a huge insurance corporation, State Farm, that has published an article under the title of Time to Break These 5 Bad Driving Habits. In it, two of the bits of advice (‘Rolling through stop signs’, and ‘Slowing down to look at crashes or construction’) are reasonable and adequately accurate. Two more (‘Running yellow or red lights’, and ‘Disregarding the speed limit’) are poor and appear to have been written by someone who truly does not know enough about the subject of safe driving. And — sadly — the fifth topic (‘Failing to signal’) is seriously flawed, as are the aforementioned state drivers manuals from which it is derived.
The advice to “signal for at least 100 feet” is unreliable in more ways than one, as follows:
a) At what speed does this “100 feet” guidance apply? Clearly, 100 feet in a 30mph limit is a much lengthier proposition than 100 feet at 70mph, and for this reason alone it cannot be correct;
b) Just how far is 100 feet? This is a scenario I have demonstrated dozens of times on advanced and defensive driver training courses across the USA. Basically, if — one-by-one — you take five individuals, on foot, to a section of road with which they are not conversant and ask them to name and describe a point that is 100 feet away, on that roadside, you are likely to get as many different answers as the number of people involved, and the distances they actually select can commonly be different by a factor of up to four! This appears to be particularly pronounced in mixed groups of males and females. So what use is an arbitrary distance — and 100 feet is arbitrary in everything except it being a nice, round number — if people typically cannot judge distances accurately?
c) What potential ‘confusions’ exist within that arbitrary 100 feet? Telling a person to signal for 100 feet is downright stupid if there is anything in that section of road to which the signal might alternatively apply (such as an intersection, driveway or business entrance before the one into which a turn is planned). Drivers need to be taught to consider all possibilities in this context and to signal at the most appropriate time… It’s not difficult!)
d) This ‘signal for 100 feet’ advice is given in some state drivers manuals in relation to lane changes on divided highways, and this is where we really do get to see the ignorance of whoever dreamt up this nonsense. At 70mph — a common highway speed, even where the limit is somewhat lower — a vehicle is covering the ground at 103 feet-per-second, so perhaps the original writer of the advice would like to explain how signaling for less than a second can even remotely be acceptable or in any way worthwhile. Most drivers know how we all typically feel if someone gives a single flash of the turn signal before pulling across and ‘cutting us up’.
In 2007, in Detroit, I presented a research paper at the Society of Automotive Engineers World Congress, under the title of ‘State Drivers Manuals Can Kill Your Kids!‘ to specifically cover this topic of stunningly bad advice being promoted to new young drivers in state drivers manuals, clearly written by people who have no in-depth knowledge whatsoever of best-practice safe driving techniques.
Footnote: Papers which the SAE publishes are subsequently put on sale by them (with the relatively modest, $27 fee going entirely to them, not the authors) and this paper is therefore available via the above link. Whilst this final comment is immodest, for which I apologize, I believe it is relevant that the paper was also voted, by the audience, into the top five percent of all of the >700 papers presented at the event and as a result was awarded an SAE ‘Excellence in Presentation’ award.