Would we need to add 2.9 lanes to the Sunset Highway if not for Westside MAX?

TriMet recently ran ads in some editions of The Oregonian claiming that "without Westside MAX, we’d need to add 2.9 lanes to the Sunset Highway."

For those drivers lucky enough not to experience the hell that is a Sunset Highway commute, know that TriMet is talking about the portion of U.S. 26 that carries vehicles between downtown Portland and Washington County. The lanes are jammed during commute hours, and we’re pretty sure some drivers would love to add an extra 2.9 lanes anyway to relieve congestion.

Light-rail trains parallel some of the highway, but not all of it. Our question was simple: We wanted to know how TriMet, the metro area’s public transit agency, calculated the need to add 2.9 lanes of highway if not for westside MAX.

TriMet spokeswoman Mary Fetsch got back to us with a calculation prepared by staff; the explanation clarified that the figure should be 2.7 lanes. (This is not the first time a query by PolitiFact Oregon has prompted a revised figure. There’s just something about us that makes people correct themselves.)

Here’s the calculation:

Basically, TriMet checked how many times a light-rail train went through the Washington Park station (westbound) and through the Sunset Transit Center station (eastbound) between 4:30 and 5:30 in the evening in Spring 2011. The total was 20 trips, or trains.

Each two-car train can carry a maximum, or full load of, 266 people, according to TriMet. If you multiply 266 by 20 trains, that’s a maximum 5,320 people on light-rail that pass through those points in that one-hour period. Compare that to the 2,052 people estimated in one highway lane over the hour. (That’s using a standard 1,800 vehicles per hour multiplied by an occupancy rate of 1.14 people per auto during a commute. )

So the maximum number of people on MAX over that hour is equivalent to the number of people on 2.6 lanes. Hence 2.6 added lanes. Again, that was in spring 2011. TriMet added another train this spring, bringing the total number of trains to 21, which translates into the revised figure of 2.7 added lanes and a maximum capacity of 5,586 riders.

Next, we turned to John Charles of the Cascade Policy Institute, who is the libertarian think tank’s leading critic of light-rail transit.

He contested TriMet’s claim on several fronts, including the theory that the analysis doesn’t account for people who could have been carried by bus if TriMet hadn’t reduced bus service for light-rail. But the most interesting suggestion he made was that maximum capacity doesn’t matter; actual ridership matters.

We asked Fetsch for the number of riders on those trains.

Weekday ridership for the 4:30 to 5:30 p.m. peak hour in spring 2012 averaged 1,673 westbound and 938 eastbound for a total of 2,611 riders. That’s not close to the maximum capacity of 5,586 riders and, using TriMet’s own calculations, comes to 1.3 added lanes.

Fetsch said TriMet’s intent was not to suggest that they would need to build 2.7 lanes to the highway corridor, which probably isn’t possible anyway unless you demolish some hills. "Our intent was to describe the mobility capacity of MAX in terms that people could relate to who travel within that corridor," she wrote in an email.

But that’s not what the ad says. It clearly states we would "need to add" lanes. That indicates that without westside MAX, we’d need that many more lanes to maintain the traffic flow we have now.

TriMet may have the capacity to carry the equivalent of 2.7 lanes, but that’s not what the ad said.

There’s an element of truth in the statement. TriMet can show a method by which it translates carrying capacity into highway lanes. TriMet may have the capacity to carry the equivalent of 2.7 lanes, but its trains weren’t carrying anywhere near that many people at the time of the estimate. And with that, we wish commuters good luck and rate the statement Mostly False.

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