Q1: I drive I-5 daily, and I consistently see drivers enter I-5 at slower speeds that 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?
Q2: 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?
A: 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 RCW 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 word “primary” used at the beginning of the last paragraph. 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.
This comment was emailed by a reader:
Part of the responsibility of those already on the highway is to enable/allow those merging to see them. This is a particular problem with entry ramps that rise to meet a highway, such as northbound I-5 at Lakeway… where drivers have a tendency to arrange themselves in the blind spot of vehicles attempting to enter the highway and sit there. Sometimes space just doesn’t allow a passenger vehicle’s mirror to clear the guardrail’s visual shadow until the merging lane is actually right next to the highway, and those on the highway need to NOT assume that they can be easily seen… or that if they are seen zipping into the blind spot, the merging driver will see them slow down once in the blind spot.
This is exacerbated by those who insist on using cruise controls in urban areas, zipping into other drivers’ blind spots, and not adjusting their speed to traffic until forced to do so (you know who you are, Mr White Cadillac Escalade on Saturday at about 1:40pm). There’s also the problem of how this affects merging traffic that is towing anything (not just semis with experienced drivers who are used to their vehicles’ limitations, but the summer-weekend boat and self-help gardener, too), which has an even-more-restricted blind spot and less ability to safely change speed quickly.