Rules of the Road

Road Rules: There is no ‘I’ in ‘freeway,’ but there is a ‘we’ when it’s time to merge safely

Though Washington law says it is the primary responsibility of the driver merging onto a freeway to do it safely, it’s more of a team activity.
Though Washington law says it is the primary responsibility of the driver merging onto a freeway to do it safely, it’s more of a team activity.

Question 1: I drive Interstate 5 daily, and I consistently see drivers enter the freeway at slower speeds than traffic is moving, causing a slow-down. I see the same with exiting drivers, who slow down to as little at 45 mph before they even reach the off-ramp, causing another traffic backup. What are the rules for entering and exiting a freeway?

Question 2: Who has the right-of-way when an on-ramp merges onto the freeway? The car on the on-ramp or the car already on the freeway?

Answer: Lately I’ve encountered a lot of questions about getting onto the freeway, and a few about getting off of it, and collectively these questions could be summed up with the two questions above. Sounds like it’s time for a refresher on how to get on and off the freeway, doesn’t it?

We’ll walk (or drive) through the steps involved, and I’ll point out what the law requires as well as what a safe driver should consider.

Let’s begin by recognizing that getting onto the freeway is actually a complex set of tasks. I don’t mean that it’s complicated; just that a driver must do several things simultaneously.

These things include changing from a relatively slow speed to a fast speed, identifying an opening in the lane of the freeway by looking both ahead and behind and changing lanes from the on-ramp to the freeway. Compare that to the driver already on the freeway who is primarily concerned with maintaining speed and lane position.

Keep that in mind; we’ll come back to it.

Most on-ramps are long enough to allow a driver to reach freeway speeds before merging onto the freeway, and most off-ramps are long enough to slow down after exiting the freeway.

As mentioned in the first question, entering (or leaving) the freeway at a slow speed can cause congestion. But of greater consequence, it increases the risk of a crash.

Traffic engineers use the term “speed differential” when describing the variation between the highest and lowest speeds on a road, and they consider it a major hazard. Enter the freeway a lot slower than the flow of traffic, and you may be met (a nice way of saying rear-ended) by another driver not expecting a slow car.

Merging at freeway speed also increases your chance of success at merging in heavier traffic. The sooner you get up to speed, the more opportunities you have to safely merge. You don’t want to be the driver that approached too slowly and watched as all the cars on the freeway zoomed by until having to come to a stop at the end of the on-ramp.

When it’s time to merge, most people, if asked, would say that the driver in the on-ramp has the primary responsibility to merge safely. And they’d be right.

But it took a bit of effort to find the legal backing for it. There is no Revised Code of Washington that specifically addresses merging on the freeway, and the laws on yielding to traffic are written for intersections, not on-ramps.

I figured that if anyone knew the answer, it would be someone tasked with enforcing laws on our state highways. I spoke with a local state trooper; he said the law I should be referencing is RCW 46.61.140, with the catchy title of “Driving on roadways laned for traffic.”

The first point of this section states that a vehicle “shall not be moved from such lane until the driver has first ascertained that such movement can be made with safety.”

Notice the words “primary responsibility” a few paragraphs earlier. Safe merging is not entirely up to the driver on the on-ramp.

In the section of the RCW on speeding, the law states that abiding by the speed limit “shall not relieve the operator of any vehicle from the further exercise of due care and caution as further circumstances shall require.” That’s a fancy way of saying that just because you’re going the speed limit doesn’t mean you’ve met the entirety of your driving responsibilities.

If you’re on the freeway and see a driver that wants to merge, you have to do your part to make sure it doesn’t end up in a crash.

Given that the merging driver has a more complex task than drivers already on the freeway and the legal responsibility of all drivers to “exercise due care,” I’m going to suggest that we consider the freeway merge a team activity instead of a competition.

Driving isn’t a game, but if it were, I wouldn’t want it to be one that divides the victors from the losers. That’s fine in Monopoly or poker, but on the road I’d choose a cooperative game that we all can win, because winning at driving means getting where we’re going safely.

Road Rules is a regular column on road laws, safe driving habits and general police practices. Doug Dahl is the Target Zero Manager for the Whatcom County Traffic Safety Task Force. Target Zero is Washington’s vision to reduce traffic fatalities and serious injuries to zero by 2030. For more traffic safety information visit Ask a question.