Tunnels & Line Of Sight

We have a few tunnels in the Portland area. A couple that I drive through on a regular basis are curved and, inevitably, if there is any traffic at all, it slows down for these tunnels.

There are the two big (three lane) tunnels that go under the West Hills and connect Highway 26 to downtown Portland. A few hundred yards down the road in the East bound lanes, the left and right lanes peel off and duck into short tunnels on their way to I-405.

On the other side of town, the exit from I-84 Eastbound goes through a short tunnel on it's way to joining up with I-205 Northbound.

I've been out to the airport a couple of times this month in the evening, after traffic has died down, and I was able to sail through at least some of these tunnels without slowing down. It was pleasant.

So it struck me that one of the reasons that people slow down for these things is the reduced visibility: you cannot see around corners. Never mind that you can see far enough ahead to avoid a collision, the problem is you cannot see as far ahead as you could just a few seconds ago, before you entered this tunnel. The sudden reduction in visibility is what causes people to slow down.

One way to deal with this is to drive in the outside lane (if there is more than one), or the outer most portion of your lane (if there is not). This will let you see a little farther ahead. I would suggest that the road painters move their lane markers (on those roads where there is room), but that would make the lane off-center in tunnel, and that would probably cause more consternation than the curve.

I wanted to include a drawing here, but that would take more time I want to spend right now.