Hoping to prevent a future of inescapable gridlock in and out of fast-growing Washington County, Metro planners have proposed sacrificing traffic lanes on Southwest Barbur Boulevard to make way for light rail or bus-rapid transit.

Barbur, which is part of Oregon 99W, has long been one of Interstate 5's most crucial rush-hour relief valves, especially when a crash freezes up the Terwilliger Curves in Southwest Portland.

Under a proposal sent to a Southwest Corridor steering committee late Monday, one of Barbur's auto lanes would be converted for a high-capacity transit line for three miles between downtown Portland and Capitol Highway and south of the Barbur Transit Center into the Tigard Triangle.

Between Capitol Highway and the Barbur Transit Center, however, the transit line would take over the existing middle turn lane, allowing four lanes of traffic in one of Barbur's most chaotic stretches of road.

It's one of several design options being recommended for further study by Metro planners.

On June 9, the steering committee – comprised mostly of elected officials from cities in the Southwest Corridor – will vote on what options deserve in-depth study as part of a draft environmental impact statement.

Metro planner Matt Bihn said a stretch of Barbur situated to the east of I-5 near Portland Community College Sylvania could actually lose a lane each way (leaving one lane in each direction for cars and trucks) if planners decide to run light rail along the route.

"If you're going to go light rail, you're either converting lanes or taking property," Bihn said.

Among other things, the environmental study, slated to be completed in 2016, would examine each proposal's potential affects on traffic congestion. Construction on a new high-capacity transit line could start as soon as 2021.

Traffic congestion between Washington County and downtown Portland isn't going anywhere.

According to Metro figures, average freight and commute times have increased nearly 18 percent in Washington County since 1980. Travel times in the Southwest Corridor are expected to increase another 30 percent by 2035, said Anthony Buczek, a Metro transportation engineer.

The other staff recommendations for study run the gamut, from a tunnel under Oregon Health and Science University and the Hillsdale neighborhood to a high-capacity transit route hugging Interstate 5 south of the Terwilliger Curves to the Tigard Triangle.

The Tigard Triangle -- a 450-acre area bound by Interstate 5 to the east, Oregon 217 to the southwest, and Oregon 99W to the north – has been identified for future redevelopment that would better mix housing, employment and shopping as the region's population grows.

TriMet is also suggesting a study of a two-branch transit line that could end in both Tigard and Tualatin.

The TriMet proposal, first reported by Metro News' Nick Christensen, would route buses with dedicated lanes or trains on the Southwest Corridor transit line from Portland to as far south as Tigard's Beveland Road in Tigard. From there, trains or buses would branch east to downtown Tigard or south to Tualatin.

TriMet declined to discuss the plan, instead referring questions to Metro.

SW Corridor Barbur conversion

Among many possible light rail or bus-rapid transit routes being proposed by Metro planners, they are recommending a study that would take lanes off Southwest Barbur Boulevard

· Barbur from downtown to Naito:

convert to one lane each direction plus turn lanes and high-capacity transit lanes.

· Barbur from Naito to Capitol (near SW Iowa St):

convert 1 of 3 northbound lanes, leaving 2 lanes in each direction plus transit lane.

· Barbur from Capitol (near SW Iowa St) to Capitol (near SW Huber St and Barbur Transit Center):

leave existing 4 lanes plus turn lanes, converting center lane to transit lane.

· Barbur from Capitol Highway (near SW Huber St and Barbur TC) to near I-5, where high-capacity transit would leave Barbur:

convert to one lane each direction plus turn lanes and transit lanes.

During public workshops to discuss potential routes for either a new MAX line or a dedicated bus rapid transit route, some commuters objected to taking lanes from motorists on Barbur Boulevard.

John Smith of Tigard has accused Metro staff of intentionally being tight-lipped about any plans to reduce Barbur's auto capacity.

Smith said he has seen Southwest Corridor documents highlighting a "Barbur concept" mixing transit, pedestrian and biking improvements.

"But never once did I find a mention of losing drive lanes," he said, adding that the concept only came up after he pressed TriMet and Metro planners at the meetings.

In recent years, Barbur has become an epicenter of ambition and conflict between various road users who want their own piece of it.

Amid Southwest Portland's hilly, circuitous network of streets, Barbur, a former railroad route, offers nearly 800 bicycle commuters a day the closest thing to a flat route. Last fall, the Bicycle Transportation Alliance called for a northbound auto lane removed to make space for about two miles of buffered bike lanes and pedestrian paths in both directions.

That idea, which was met with resistance from the Oregon Department of Transportation, quickly lost steam.

Without the throughfare, state traffic engineers say, daily freeway gridlock through the Terwilliger Curves would be even more nightmarish.

Barbur is a "seismic lifeline route that takes on double the traffic several times a month when when a crash closes lanes on I-5," Jason Tell, ODOT's Portland area manager, said at the time.

But now Metro is talking about sacrificing even more of the highway for a dedicated high-capacity transit line.

ODOT spokesman Don Hamilton said the agency would welcome a thorough study of how removing auto capacity would affect congestion.

"We don't have any concerns at all about studying the idea," Hamilton said. "It's one of the crucial pieces of the process -- taking a serious look at the impacts of these ideas."

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-- Anna Marum of The Oregonian contributed to this story

-- Joseph Rose