The replacement of the SR 520 Bridge continues to be a high priority project, as the need for safety improvements and transportation enhancements remains great. However, the options currently under consideration are limited in their creativity, focusing primarily on what planners call the "Goldilocks Set" — a four-lane alternative that is "too small," an eight-lane alternative that is "too big," and a six-lane alternative that is "just right."

Although other ideas have been suggested in the past, such as a group of drivers calling for a dedicated SUV bridge and a so-called "Chartreuse Green Alternative" that appears to be focused on the color of the bridge, it is only in the last few weeks that some truly visionary ideas have been proposed, such as the following:

The "Rabbit Hole" alternative. This would consist of interlocking bored and/or floating tunnels that serve multiple locations on the east and west sides of the lake. On the west side, there would be tunnel entrances at Sand Point, Laurelhurst, Madison Park, and Madrona Park, while on the east there would be entrances at Kirkland, the Point Cities, and Mercer Slough in Bellevue. All of the tunnels would meet in a submerged roundabout in the center of the lake, so that vehicles would be able to get to various destinations. This would decentralize traffic, therefore allowing it to be absorbed by existing roads (e.g., Madison Street, Sand Point Way, etc.), thus eliminating the Portage Bay viaduct and connections through Montlake.

The "Train to Anywhere" proposal. This would involve creating a six-lane bridge with tracks in all six lanes. At the Seattle side, one set of tracks would run north over the Montlake Bridge, and then split and run on the surface down Sand Point Way and NE Pacific, another would run south along 23rd Avenue with a spur through the Arboretum, while the third line would continue to I-5 and run in tracks embedded in those lanes as well. This alternative assumes that there will be virtually no cars in the future, so there is no need for lanes for them. Any remaining vehicles other than trains (such as horse and carriages) can share the rail lanes (as is done in the Third Avenue tunnel currently). Trains running the in the same lane will notify the horse and carriage operator via GPS, and the operator can move his vehicle to one of the unoccupied lanes. This will require the nimble use of technology as well as genetically modified (GMO) horses that can shift from side to side very quickly.

The "Greener Than Thou" proposal. This would rebuild the bridge with only a pedestrian/bike path. There is a variation on this proposal, called the "Lemming Alternative," which would include vehicle lanes, but terminate them at the current "Ramps to Nowhere" in the Arboretum.

The "Zero Lake Option." This was inspired by the bold and visionary actions of our ancestors, who reshaped the landscape in major ways such as the Denny Regrade, the rerouting of the Cedar River into Lake Washington, and the lowering of Lake Washington by nine feet. Proponents of this option ask the logical question: 'If we can do nine feet, why not the whole Lake?" The savings in concrete are enormous, as is the potential for development on the slopes and valley floor that would now be available. There are moderately significant impacts on fish resources.

The "Dunkirk Strategy." This alternative was inspired by the heroic World War II experience when yachts and fishing boats were mobilized to evacuate the British Army from France when Hitler overran the continent in 1940. Since there are many yachts and pleasure boats in the Seattle area, most of which are only used a few hours a month, why not mobilize a Dunkirk Fleet of hundreds of these small boats to carry people across the water instead of rebuilding the bridge?

The "Sustainable Surface" alternative. This proposal is designed to counteract the impact of global warming on Lake Washington by submerging a system of pipes under the SR 520 corridor, and then continually pumping liquid nitrogen through them to create a frozen surface. The cooling effect would spread through the Lake and protect fish against excessively warm temperatures. Travel across the Lake could be by dogsled caravans, and there could be year-round winter sports adjacent to the travel corridor. Since the ice bridge could not be raised to allow boats to go through, there would be an icebreaker stationed in the corridor, which would simply break through the bridge at regular intervals, and allow it to refreeze to restore travel across the Lake.

Perhaps the most radical proposal is the "Cloud Suspension Bridge." This would synthesize the use of cloud computing with visualization techniques and nanotechnology to construct a bridge suspended by trillions of nanowires connected to individual droplets of rain and microparticles above the bridge. As particles fall or dissolve, new nanowires will be deployed using spider-like spinnerets to seek out newly formed droplets and dust. The bridge will look like it is suspended from thin air. On extremely windy or clear days when this technology may be unstable, drivers will rely on visualization techniques to imagine that the bridge is still working, as they already do in its current condition.

It is important that all reasonable choices are considered as we move through the key stages of decision making on this critical transportation facility. These and other ideas will now move into the state's process for selecting a Draft Preliminary Preferred Alternative in April. Following public hearings on the draft in May, a Revised Draft Preliminary Preferred Alternative will be recommended in June, followed by a public hearing in July. Based on the response from this hearing, in September the state will select a Consensus Draft Preliminary Preferred Alternative, which will have a public hearing in October. After that there will be a Revised Consensus Draft Preliminary Preferred Alternative, which the state will consider in a Decision Agenda at a meeting to be determined at some point in the future. Once this meeting has taken place, there will be an opportunity for further public comment prior to the state selecting a Final Preliminary Preferred Alternative, which will then move into the next stage of the decision-making procedure.

This jeu d'esprit is reprinted from Conlin's April 1 edition of his e-newsletter, "Making It Work." You can get the newsletter by mailing richard.conlin@seattle.gov.