Eastside transit: Is blend best?

The best future transit system for the Eastside may be a hybrid of several systems, a new Sound Transit study concludes.

Light rail should be built on Interstate 90 across Lake Washington, it suggests, but more frequent, trainlike bus service may make more sense for getting riders from Bellevue to outlying destinations such as Redmond and Issaquah.

"It is clear that no one technology best addresses the needs of the entire [Eastside] subarea," the report says. "Different technologies work better in different environments."

The study, prepared for Sound Transit by several consulting firms, is a milestone for the agency at it prepares to submit a new package of regional transit projects to voters, perhaps next year. The Sound Transit board is expected to take the first step toward that vote this spring by adopting a plan that identifies what should be built in each corridor.

On the Eastside, the question of what kind of transit to build across I-90 — light rail, monorail or "bus rapid transit" (BRT) — has divided the region for years. The new study provides the first side-by-side ridership and construction-cost comparisons.

They point clearly toward light rail. Advocates of BRT — bus service designed to mimic rail — said the study is biased.

The study says light rail in I-90's reversible center roadway from Seattle to Bellevue Way Southeast would attract at least 33 percent more riders than the other alternatives, in part because riders wouldn't need to transfer to another planned light-rail line running from downtown Seattle to Northgate.

Sound Transit, which now is building its first rail line from downtown Seattle to Tukwila, doesn't have the money to build the line to Northgate now.

A BRT line sharing I-90's HOV lanes would cost only a fraction as much as light rail, the report adds. But to get that line to downtown Bellevue, it says, the I-90/Interstate 405 interchange would need to be rebuilt to create ramps linking HOV lanes, a project that could cost up to $2.5 billion.

Light rail from I-90 to downtown Bellevue along Bellevue Way and 112th Avenue Southeast would cost less than that, the study adds — especially if an elevated alignment through downtown Bellevue is chosen rather than a tunnel.

Critics said the consultants gave Sound Transit a report that confirmed its preconceptions. "This report, like others Sound Transit has produced, is meant more to sell their preferred solution than to inform," said Richard Harkness of the anti-rail group Citizens for Effective Transportation Alternatives (CETA).

Rebuilding the 405/90 interchange to accommodate BRT may not be as costly or ambitious as the study assumes, the BRT backer said.

Monorail generally fares poorly in the report. The study says monorail would have to run on the surface in I-90's center roadway because the bridge can't handle the weight of columns. It also says trains manufactured by Hitachi — the firm with which the Seattle Monorail Project is working as it plans a line from Ballard to West Seattle — wouldn't fit in the I-90 tunnel under Seattle's Mount Baker Ridge.

Trains made by another company, Bombardier, would fit, the report says — but only if the floor of the tunnel is lowered, driving up costs.

Those concerns may be legitimate, said Cleve Stockmeyer of the advocacy group King County Monorail, but monorail still warrants consideration across Lake Washington on Highway 520. "Monorail gets you from Redmond to downtown in 23 minutes," he said.

The Sound Transit report does not consider travel times. It also doesn't look at rail or other "high-capacity" transit across Lake Washington on 520, because an interagency committee several years ago identified I-90 as the best corridor.

The Sound Transit board will be briefed on the report this afternoon. Kenmore City Councilman Jack Crawford, one of three Eastside representatives, said he looks forward to light rail on I-90.

"I think we really are looking for dedicated rights of way for Sound Transit in the future, because highways are going to just be jammed," he said. "The population will go up, there'll be more vehicles, and even with HOV lanes we're going to have problems."

Bellevue Mayor Connie Marshall, another board member, said she hasn't decided between light rail, monorail or BRT, but that whatever is chosen should not be stuck in traffic with cars.

"It should be inside its own dedicated right of way," Marshall said.

All but one I-90 option would deprive Mercer Island residents of the access they now enjoy to the freeway's center roadway, otherwise reserved for car pools and buses. "I think most islanders embrace the reality that we will be part of a regional solution," Mayor Alan Merkle said, so long as that solution includes some type of accommodation for residents, such as expanded parking or bus service.

Beyond downtown Bellevue, the Sound Transit study also looks at transit alternatives north to Totem Lake, northeast to Redmond and east to Issaquah.

Generally, it concludes, BRT in HOV lanes would be less expensive and would carry about the same number of riders as light rail, monorail or BRT on roads built exclusively for buses.

One exception: the corridor from downtown Bellevue to Overlake, where an HOV-based BRT line would require expensive reconstruction of the 405/520 interchange. BRT on a "busway" south of 520, through industrial land the city of Bellevue hopes to redevelop, would be the least-expensive option there, the report says.

John Niles, another CETA leader, criticized the report for appearing to rule out BRT on I-90 but applauded its conclusions for the other corridors. "Buses just give you a lot of opportunity because of the flexibility," he said. "BRT is looking better and better."

The report says an all-light-rail system linking Seattle, Bellevue, Totem Lake, Redmond and Issaquah would cost at least $4.6 billion in today's dollars. A comparable monorail system would cost at least $5 billion, a BRT HOV system $4.4 billion, a BRT busway system $3.1 billion, according to the report.

Those numbers don't account for inflation or financing costs.

Operating costs are highest for light rail, the study says.

Voters approved the first round of Sound Transit projects in 1996. All are scheduled to be finished by 2009. While Seattle, South King County, Snohomish County and Pierce County are getting light rail or commuter rail (or both), all of the Eastside's projects are bus-related.

They also aren't as costly. Sound Transit estimates that, if current taxes are collected through 2020, it will have $1.6 billion in unused financial capacity to use for new projects.

Any new package is almost certain to call for tax increases across Sound Transit's three-county district.

Eric Pryne: 206-464-2231 or epryne@seattletimes.com