Light Rail

Portland's Light Rail System Can't Take the Heat

High temperatures disrupt service, exposing problems with the system's design.


MAX blue line in downtown Portland
Richard Eriksson

Portland's recent heat wave brought residents a brief respite from the usually cool and wet Northwest weather. It has also unfortunately brought with it a respite from timely and efficient public transit.

As temperatures rose above 90 degrees Fahrenheit throughout August, the city's Metro Area Express (MAX) light rail system reported severe service interruptions across its entire network. Trains were forced to slow to a crawl or sit idly in between stops, leading to drastically extended commute times and a flurry of angry online comments directed at TriMet (Portland's largely taxpayer-funded public transit authority).

TriMet has explained that the delays were the result of a phenomenon known as "sun kinking," which is when higher-than-usual temperatures cause rail and power lines to expand and buckle, forcing trains to reduce speeds or stop running altogether.

This explanation has been the standard response from TriMet over the years, but as the Willamette Week (a weekly Portland newspaper) was quick to point out, plenty of other light rail systems in the country experience similar or hotter temperatures without the same service interruptions.

Phoenix, Arizona, routinely sees temperatures far in excess of Portland's. However, its Valley Metro light rail service has proven immune to heat-related service delays. Valley Metro Public Information Specialist Ann Glaser writes in an email that Phoenix's system has been able to avoid such problems by setting its tracks in concrete and calibrating its power cables to withstand high temperatures, things she says it was able to do without a significant increase in construction costs.

Portland's MAX incorporates none of these features, instead laying its rail lines directly on gravel in many places. TriMet's explanation is that its system "is designed for the average temperature ranges of our local climate." But this claim seems suspect given that the brains behind Seattle's light rail system decided local climate conditions—which are nearly identical to Portland's—warranted Phoenix-style concrete-supported tracks. As a result, the Sound Transit authority has had to issue no service delay warnings due to heat, despite temperatures rising above 90 degrees multiple times this year.

TriMet is currently experimenting with limited fixes to the most severely affected areas of track. However, networkwide fixes are still years away. But that didn't stop the agency from spending some $1.49 billion on the new MAX line completed in September 2015 that—you guessed it—was built with the same rail-on-gravel design, ensuring sun-kink-caused delays will be a summertime ritual for even more commuters.

This will no doubt frustrate Portland's small businesses, a portion of whose payroll taxes go to TriMet. A business with a $1.5 million payroll already owes $10,856 per year (and rising) in such taxes. One wonders how successful those small businesses would be if they, like the transit authority, hiked their prices while providing sporadic service to customers.

Correction 9/9: An earlier version of this article suggested TriMet is an arm of the city government. It's actually an independent agency.

Correction 9/20: This article originally described $10,856 as the amount an average small business in Portland owes in payroll taxes. It's actually the amount owed by a Portland small business with a $1.5 million payroll. TriMet also reached out to clarify that 15 miles' worth of its tracks are embedded in concrete; the other 45 miles are laid on on gravel. The text has been updated.