Traffic Q&A: Does rain mean mandatory headlight use in Washington?

Q: Aren’t we required by law to have headlights on when it’s raining? – Ted N., Tacoma

A: One might think, with Washington’s reputation for rain, that such a law would be on the books.

But it’s not. Not exactly anyway.

RCW 46.37.020 spells out when a driver should turn on the headlamps on their vehicle:

“Every vehicle upon a highway within this state at any time from a half hour after sunset to a half hour before sunrise and at any other time when, due to insignificant light or unfavorable atmospheric conditions, persons and vehicles on the highway are not clearly discernible at a distance of one thousand feet ahead shall display lighted headlights …”

So, aside from the obvious hours of darkness, visibility is the key to mandatory headlight use.

Can’t see 1,000 feet ahead because of rain, sleet, snow or wildfire smoke? The law requires you turn on your headlights.

Conversely, said Washington State Patrol trooper Shaneka Phillips, “If it’s sunny and lightly raining at the same time during the middle of the day, you may not need your headlights on.”

We here at Traffic Q&A headquarters are notoriously bad at judging distances (what does 1,000 feet look like, anyway?), so we turn on our headlights if there’s a cloud in the sky.

Can’t hurt, said Tacoma police spokeswoman Loretta Cool.

“Yes, headlights on any time vision is limited is the best solution,” she said.

“There are, for example, headlight zones in the mountain passes. Those require headlights during daylight hours as it increases the visibility of oncoming cars around the curves.”

Q: As far as speed limits go, is there a minimum speed that motorists must travel? As you may have noticed, extremely slow drivers cause accidents, too. – Chuck D., Tacoma

A: Yes, but it is in the eye of the beholder (or state trooper).

Here’s a portion of Section 1 of RCW 46.61.425:

“No person shall drive a motor vehicle at such a slow speed as to impede the normal and reasonable movement of traffic except when reduced speed is necessary for safe operation or in compliance with the law …”

Now, there are stretches of highway where the state secretary of Transportation or local authorities might decide a mandatory minimum is necessary. Such roads would be posted accordingly.

Neither we nor Phillips could think of any in or around the Pierce County environs, however.

This story was originally published April 17, 2016 at 5:00 AM.