TriMet is preparing for an $11 million project to shore up MAX tracks on the Steel Bridge, the light-rail system's primary bottleneck.

The work, the bulk of which is still as much as five years away, would focus on replacing 30-year-old track installed when MAX first debuted in Portland, allowing trains to move more quickly over the bridge.

The move is TriMet's latest effort to resolve reliability issues that have dogged the system. It will be doing two weeks of disruptive work later this month to replace track in the Rose Quarter, and earlier this year it replaced a length of aging track along First Avenue in downtown Portland.

Trains currently travel no faster than 10 mph when crossing the bridge. After the repairs, travel speed could increase to 15 or 20 mph.

The Steel Bridge project would also aim to resolve signal issues that have caused service disruptions. Recurring drainage problems have tripped up sensors in the bridge, triggering signals that trains aren't clear to cross.

Staffers, citing the complicated nature of the work, are asking the agency's board of directors to let it forgo the usual process of selecting the lowest-bidding contractor, instead opting for the most-qualified firm.

The technical work is also why the price tag is much higher than other recent track replacement projects. The First Avenue project cost $2.1 million, and the Rose Quarter track work is expected to cost $2.5 million. The Steel Bridge work is expected to cost around $11 million.

"It's an old and aging structure," said Amy Fandrich, a TriMet capital projects manager. "And it's working over water."

MAX trains cross the bridge more than 600 times each weekday.

TriMet is also studying the long-term future of the Steel Bridge.

It hired engineering consultancy CH2M Hill earlier this year to assess the short-term repairs while also coming up with options for increasing the bridge's carrying capacity, including assessing a possible replacement. The firm will be paid up to $800,000.

Its findings aren't yet complete, and Fandrich said the long-term work could still be 30 years away.

-- Elliot Njus

enjus@oregonian.com

503-294-5034

@enjus