Of cars, lanes and neighborhoods: discussing the new Sellwood Bridge [updated]

Deck arch Sellwood Bridge design option (rendering courtesy Safdie Rabines Architects) 

Interested in design options for the new Sellwood Bridge?  The architect for the project, Ricardo Rabines, will give a free lecture on Monday, August 30 at 3pm at the American Institute of Architect’s Center For Architecture at 403 NW 11th Ave.

But don't expect Rabines to be able to answer the larger question surrounding this bridge: how we balance the needs of transit with those of neighborhoods.

The Sellwood Bridge project is a planning effort to replace the 85-year old Willamette River crossing in Southeast Portland. A preferred alternative to replace the bridge was approved at the local level in 2009. The project is currently in a preliminary public process phase that will determine the type of bridge structure to be built. Multnomah County expects to select the structure type for the new bridge later this year.  Construction should begin in 2012.

Ricardo Rabines is a co-founder of Safdie Rabines Architects in San Diego.  His award-winning work includes designs for bridges in San Diego (such as the Scripps Crossing pictured below) and Des Moines, Iowa.  "Ricardo likes to say that each bridge he works on has its own personality that relates to its site and community needs," Multnomah County spokesman Mike Pullen told me.

 
Deck arch Sellwood Bridge design option (rendering courtesy Safdie Rabines Architects) 

Currently involved in a variety of projects around the country, some of Safdie Rabine’s recent commissions include the South Campus Student Center at UCLA, the Structural and Materials Engineering Building at UCSD, and the El Centro Family Courthouse. Projects recently completed include The Robert Paine Scripps Forum for Science, Society & the Environment at the Scripps Institution of Oceanography and Baldwin Hills Scenic Overlook State Park in Los Angeles. Their work also consists of several vehicular and pedestrian bridges such as the Harbor Drive Pedestrian Bridge in downtown San Diego.

The preferred Sellwood Bridge alternative selected through public input is a new two-lane bridge with two sidewalks, two shoulders/bike lanes and a traffic signal at the west end connection with Highway 43. Any new bridge must also the following criteria: a cross-section without a raised center median, a total cost of less than $330 million, no long term traffic closures, a construction footprint that minimizes impacts to adjacent businesses and residences, and room to accommodate a future streetcar.

There are eleven bridge types currently under consideration that are possible with new construction techniques and the alignment chosen in the preferred alternative. The alignment will be approximately 15 feet south of the existing Tacoma Street centerline to allow for continuous traffic flow at the crossing throughout construction. The possible bridge types include deck structures (no superstructure above the deck) and thru structures (support structure above the deck).

Scripps Crossing, San Diego (photo courtesy Safdie Rabines Architects) 

Although the renderings included in this post only show one of the bridge design option, the deck arch, I was surprised at how similar it looked to the existing Sellwood bridge. I'm no expert on this, admittedly, but if we build a bridge that looks and performs like the old bridge, why aren't we just fixing the old one?

I was shocked to learn that the preferred alternative here is a two-lane bridge. This is the only bridge over the Willamette for miles in either direction, and we want to keep allowing only one car in each direction? What century is this?

Naturally I say this with the understanding that accommodating too many car lanes can lead to sprawl. And we have to consider the streets that feed onto and off of the bridge. In the case Southeast Tacoma Street, on the east side of the Sellwood Bridge, it is indeed just one lane in each direction. But on the other side, the bridge is fed by multi-lane Macadam Avenue and Highway 43. Thousand of commuters use this bridge every day to get back and forth between Clackamas County, Southwest Portland and Lake Oswego. Is tearing down one bridge with a single lane in each direction and building another bridge with a single lane in each direction really the best investment we can make for the future with this infrastructure?

Deck arch Sellwood Bridge design option (rendering courtesy Safdie Rabines Architects) 

It seems to me the Sellwood Bridge has an inherent identity crisis that has never been fully resolved by the bridge design process. For the west side, this is an important connection affecting major traffic arterials. It's about moving cars. For the east side, it's more about protecting the modestly scaled local neigbhorhood of homes and businesses. We don't want multiple lanes of cars zooming dangerously fast past the antique stores of Sellwood.

I'm not saying one side of the bridge occupies moral or functional high ground over the other. But if some are expecting an improved commuter bridge with reduced traffic and others are expecting a modest replacement of a modest neighborhood span wherein minimized impact is of greater importance than maximized movement, how can we possibly design a bridge that will satisfy?

It's not designer Ricardo Rabines' job to settle the Sellwood Bridge's inherent conflict about what it should be. He's here to present different off-the-shelf bridge types and work with us to select one and then make it fit our local context. But it strikes me that the Sellwood Bridge is more than infrastructure we have to replace. It's part of a larger conundrum we haven't solved: how to balance moving traffic with preserving neighborhoods.

[Update, 8/30/10] A couple days after initially posting this article, I'd like to pass on comments from Mike Pullen of Multnomah County on the bridge. Perhaps the single lane in each direction is the only way to go:

"Traffic studies showed that a four lane bridge would not improve congestion, due to the two-lane layout of Tacoma St. and the traffic signals on that street. Brian is correct that more than two lanes are needed at the west end of the bridge, where traffic turns north to Portland or south to Lake Oswego. The bridge will have four lanes at the west end to increase the flow of traffic through a signalized intersection there. The signal will be adjusted to give more green time for traffic in the dominant direction, depending on the time of day. The best improvement in congestion will likely be for Portland to Lake Oswego traffic, which will pass under the new bridge. That traffic should be able to avoid the afternoon congestion at the bridge."

Comments

[Bob R.]

"and we want to keep allowing only one car in each direction? What century is this?"

This is the century in which we recognize factors such as Induced Demand, Peak Oil, and transportation's contributions to global-warming emissions.

This is a century in which we listen to a local community with distinct identity which is already facing issues with high volumes of out-of-area commuters coming through, and doesn't wish to experience greater impacts from additional commuter traffic.

This is a century in which we realize that a widening of the Sellwood bridge, and the traffic that would bring, would require a very expensive and disruptive widening of Highway 43, which I'm sure the residents and businesses in Johns Landing would like to have some say about.

This is a century in which we recognize that Land Use planning must go hand-in-hand with Transportation planning.

Thanks for asking! :-)

[MP]

Couldn't agree more with Bob R., well said!

[Brian Libby]

Okay, okay. I see your point, Bob, MP and others feeling the same way. Normally I'd like to think I'm on the green/sustainable side of any argument like this. I don't want sprawl and cars to dictate things AT ALL. I'm definitely in favor of progressive land use planning. I just didn't think two lanes in each direction for a US highway or a key bridge in a major city was being that unreasonable.

[Mudd]

Being a regular user of the Sellwood Bridge, it seems to me like it functions quite nicely the way it is...except, of course, for the could-crash-down-killing-a-bunch-of-people thing. Sure, there are some bottleneck issues occasionally, but I'd hate to see a really big bridge into Sellwood. The only thing I'd add would be tracks and good bike lanes and sidewalks.

[billb]

Looking at the sketch I wonder if it is just repeating the typical current street layout , and is missing a great opportunity to be more. How about broad strolling sidewalks with benches , tables , and shade trees ? The view is great , why not celebrate it!

[Potestio]

One interesting fact I learned on a recent bike realted information tour to Amsterdam was that the Dutch will build new arterials in the Amsterdam region with only one motor vehicle lane in each direction. They believe, based on their studies and experience, that one lane is actually more efficient in high volume conditions because it forces drivers to move at a more consistent speed and with more direct behavior. It eliminates all the lane changing and jostling that two lanes induces. It forces a certian level of pressure on each driver to focus and to maintain proper distance and speed. Of course they augment reduced "capacity" with rail and bike lanes.

By restsicting the new Sellwood Bridge to two lanes, but adding bike lanes and a provision for future street car, we are following the lead of one of the most progressive countries in the world when it comes to transportation planning.

My concern for this bridge is aesthetic.

The current drawings shown above ( one of many options ) give me concern that the bridge will be "enhanced" with the sort of victorian foppery common to modern design. Do we really need the protruding bulbous sidewalks at the pier points of the bridge? What purpose do they serve other than to complicate the structure and add cost?

The Vista Viaduct demonstrates that benches and viewing points can be integrated into the design without destroying the general integrity of the structure.

If room is needed for viewing, would it not just be easier to add a foot or two to the width of the sidewalks? Is there not a way to better integrate rest stops?

This bridge absolutely must be a great addtion to Oregon's bridge design tradtion and collection. We cannot build another bridge like the new Sauvie Island Bridge which has such an unfortunate but well intentioned image driven mash-up of structural components, materials and poorly exectued details.

[Greg Moore]

As a former daily-commuter over the Sellwood bridge, I for one don't see an immediate need to widen it to more lanes. It handles traffic nicely now. I like what Potestio pointed out regarding how the Dutch approach their roadways. It's an interesting argument and case study. This isn't a major arterial and I think the folks who live, visit and drive through would prefer it to stay that way. Aren't we building a new transit bridge in downtown to enable better public transportation connectivity between east and west?

The sketch that Brian posted from Rabines looks great! I think it celebrates the existing bridge's character that has long been an easy association with the Sellwood neighborhood. Remember that a bridge is ultimately a utility to get cars, streetcars, people, communications lines, natural gas (?) and electricity (?) across the river.

If we can make it look attractive and serve all the needs without overrunning budgets, great. But, let's cut the whining about how we're "missing opportunities" for "something better." Every designer thinks they can do better.

One pratical point: Benches and wide sidewalks aren't ideal on a bridge. They'll simply attract vagrants and vandalism. I doubt this is what Sellwood residents would like to attract to their neighborhood. I really like the idea of safe bike lanes and an eventual streetcar.

Oh - Bob R.'s answer to the question of "what century are we living in" is quite entertaining and true. It seems like it's more of a coincidence that the Sellwood Bridge is not being expanded like other arterial roads. I suspect the factors keeping the bridge small have more to do with the neighborhood, current traffic volume and budget. You can bet that if there was a master plan to make the Sellwood bridge a major duct in the road system, it would just happen without anyone having any real say in the matter.

[Mike Pullen]

Here's a little background on the two lane cross section for the new bridge.

Traffic studies showed that a four lane bridge would not improve congestion, due to the two-lane layout of Tacoma St. and the traffic signals on that street. Brian is correct that more than two lanes are needed at the west end of the bridge, where traffic turns north to Portland or south to Lake Oswego. The bridge will have four lanes at the west end to increase the flow of traffic through a signalized intersection there. The signal will be adjusted to give more green time for traffic in the dominant direction, depending on the time of day.

The best improvement in congestion will likely be for Portland to Lake Oswego traffic, which will pass under the new bridge. That traffic should be able to avoid the afternoon congestion at the bridge.

[Potestio]

Thanks to Mike for clarification on the lane issues. Adding capicity is best accomplished by using more efficient modes, like bus, streetcar or bikes, or even using smaller cars. Slower speeds also allow for tighter distances between cars and are safer for all.