Advertising

Friday, April 24, 1992 - Page updated at 12:00 AM

E-mail article     Print

Getting There

How Bright Really Right In Today's Headlight?

Usually, failing to dim your lights at another motorist doesn't end in gunfire.

But that's what happened near Vancouver, Wash., last January when Randy Korth was driving along in his car and another car came up behind him with its high beams on. Somehow, words were exchanged. Then a man got out and shot Korth in the neck.

On April 10, Robert Wrinkle was found guilty by a Clark County jury of attempted first-degree murder and Eric Tichrob was convicted of second-degree assault in the incident.

Granted, such violence is unusual, but headlights certainly are a common curse in getting there. The problem seems common at this time of year when lights tend to fail after a winter of use.

As with many things in transportation, what you're seeing is evolution.

The evolution was basically stalled in this country from 1937, when sealed-beam headlights were introduced, until 1974, when halogen headlights were allowed because of the energy crisis.

Major differences are that halogens are brighter and the entire light assembly often doesn't need replacing; instead, you just replace the bulb.

The evolution included a 1977 change that allowed cars to have headlights of up to 150,000 candlepower, instead of the previous 75,000 candlepower.

But most car wiring wouldn't support such an electrical load. Switching to halogen gave more light using less current.

It's still not enough, however. All car lighting systems face a

basic quandary - if they're bright enough to allow safe driving, they blind oncoming drivers.

High beams of 150,000 candlepower will show a human figure about 530 feet away in good visibility. A car going 80 mph takes about 550 feet to stop, including a two-second driver reaction time. So if you're driving in rain with low beams near that speed, you'll see danger too late.

Also, a rock cracking the lens of a seal beam makes the filament burn out instantly, but with halogen lights, the inside bulb keeps burning even though moisture gets inside the lens.

In addition, heating and cooling make the light act like a bellows, drawing moisture inside if cracks develop.

"Moisture will degrade the performance of the light," says Jack Oliver of General Electric's product-development branch in Cleveland. "Moisture will tend to degrade the reflector rapidly."

If you're lucky, that replacement will cost $10 or so for just the bulb; on some cars, replacing the entire lens assembly can cost $200.

Incidentally, says Oliver, all lights burn out. The industry standard is a test that says after 320 hours of use, half the lights in a test group will burn out and half will be on - using lights 2 hours a day, that means you could expect about 5 months of continuous service, although headlights obviously often last far longer.

Traffic notes:

On Interstate 5, expect northbound slowing overnight Wednesday near North 175th Street as traffic-data equipment is put in.

Elsewhere on I-5, the Northeast 85th Street on-ramp and the Northeast 80th Street exit will be closed from 6 a.m. to 6 p.m. tomorrow for HOV lane installations.

Chuckanut Drive near Bellingham is closed every morning for the next two weeks for construction work.

And expect slowing on Highway 18 near Southeast 312th, 296th and 208th streets as widening is done.

Got a traffic problem, beef, suggestion or question to share with us? Call 382-8899, weekdays or write "Getting There," The Seattle Times, Box 70, Seattle, WA 98111.

"Getting There" appears Wednesdays and Fridays in the Northwest section of The Times.

Copyright (c) 1992 Seattle Times Company, All Rights Reserved.

advertising


Get home delivery today!

Advertising

Advertising