Research

Part I: The Present Chaos

In 1978 the National Bureau of Standards wrote 167 pages on emergency vehicle warning lights. It opened the first section with the words “The Present Chaos” — and forty-eight years later almost none of what it recommended has happened.

A government report that calls the situation chaos

Emergency Vehicle Warning Lights: State of the Art was published in September 1978 as NBS Special Publication 480-16, written by Gerald L. Howett with Kenneth L. Kelly and E. Thomas Pierce of the Center for Building Technology, for the Law Enforcement Standards Laboratory. It ran 167 pages and sold for $3.50.

Government technical reports are not usually blunt. This one divides itself into three parts, and the first is headed, without apparent irony, Part I: The Present Chaos.

The opening diagnosis is worth reading slowly, because everything that follows in the next fifty years is contained in it. There is no single standard or recognised form of marking for emergency vehicles in the United States, the report says, as there is in Great Britain. The result is confusion among motorists and pedestrians — a proliferation of lights that look alike but call for different behaviour depending on which vehicle carries them and which locality you happen to be in.

And then it turns to the driver of the emergency vehicle, who the report says is in an unenviable position: in constant danger, because he does not know whether the driver ahead will understand his signal or react correctly to it. An out-of-town motorist, meeting a local convention he has never seen, may respond in a way that endangers himself, the traffic around him, and the emergency vehicle itself.

How bad the variation actually was

The report reproduces a survey presented to the National Committee on Uniform Traffic Laws and Ordinances in November 1971. It is a remarkable piece of bookkeeping.

Sixteen states allowed blue — and among those sixteen there were six different rules about how the blue was allowed to move. Rotating, oscillating, flashing, alternately flashing, or simply unspecified. One of the four in the first category was Illinois, where the permission applied to Chicago only.

Fire vehicles were worse: six states permitted blue, eighteen permitted red, one restricted its flashing red to fire police and another to fire captains. The same colour meant a different thing depending on the county line you had just crossed.

The question nobody answered

Beneath the inventory sits a genuinely deep question, and the report states it cleanly: should the reaction expected of a driver differ depending on whether the vehicle approaching is a police car, a fire engine or an ambulance?

There are two philosophies, and American practice mixes them. In one, the light tells you what to do — a flashing red on a moving vehicle means pull right and stop, and nothing else matters. In the other, the light tells you what the vehicle is, because police, fire and ambulance services all want distinctive identification.

Try to satisfy both at once, across fifty states, and the number of configurations a driver must learn becomes, in the report’s word, excessive.

Its recommendation is modest and clear. If the object is simply to clear a path, the sensible answer is one set of warning light configurations, with vehicle identification left to the paint and markings, which a driver can read at distance anyway. In the absence of contradictory evidence, it concludes, the ideal system in any jurisdiction — and most desirably in all of them — would include only one to three distinct signal light patterns, each requiring a different reaction.

The compromise it offered instead

The report is realistic about American federalism. Knowing that full agreement was unlikely, it proposes a fallback that requires almost nothing of anybody.

Agree on one colour. Let yellow always mean danger from a slow-moving or standing vehicle, and let the lights indicating a rapidly moving vehicle be any other colour a locality prefers. Drivers would learn a yellow-versus-other system easily. A specific pairing — yellow and red, yellow and blue — would let them react slightly faster still.

That is the whole ask: national agreement on a single colour’s meaning, everything else left to local choice.

What happened to the recommendation

The honest answer is that the chaos is still there, and we have a recent measurement of it.

The 2020 Virginia Tech survey covered in why American police cars look the way they do catalogued fifty city and forty-nine state police forces. It found eleven colour schemes, ten logo shapes, three striping styles, and nine agencies running no logo at all. Britain, which the 1978 report held up as the counter-example, went the other way and specified markings recognisable nationwide from 500 metres.

And the same 2020 work found the deeper problem that the 1978 report predicts without quite naming: conspicuity of that kind is learned. Battenberg works in Britain because British drivers were taught it. It does not increase conspicuity in the United States, because there is nothing to have learned.

Forty-two years, two administrations of the same underlying question, and the same answer: the signal is only as good as the agreement behind it, and there is no agreement.

What the report does not say

Two things worth stating, because this is a document it would be easy to over-read.

It is a state-of-the-art survey, not a standard. The Law Enforcement Standards Laboratory produced several kinds of document — voluntary equipment standards, user guidelines, state-of-the-art surveys — and this is the third kind. It describes and analyses; it does not mandate. The authors also note that their own experimental work was to be reported separately, so this is the literature review rather than the laboratory findings.

And it is 1978. Its catalogue of hardware is a period piece in its own right — rotating bases carrying sealed-beam lamps, oscillating units sweeping through 95 to 110 degrees, figure-eight patterns, and an extensible roof platform electrically raisable four to seven feet above the roof. None of that describes a modern LED bar. The perceptual analysis survives the technology change; the equipment list does not.

Why these three documents belong together

Read in sequence they make an argument no one of them makes alone.

1978 said the system had no agreed meaning. 1982 and 1984 said the most prominent piece of hardware in it was not earning its place. 2020 said that making that hardware brighter makes the officer harder to see.

Every one of those was published at public expense, sat in a public archive, and changed almost nothing. That is not a conspiracy. It is what happens when a decision belongs to eighteen thousand separate agencies and no two of them have to agree.