Submission 5: Metroman - Ivy Tunnel

Discussion in 'Pedestrian Bridge Design Charette' started by 3Dementia, May 15, 2009.

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How would you rate Submission 5 out of ten?

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  1. 3Dementia

    3Dementia Senior Member

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    Note: it is the responsibility of the designer/submission to ensure all images are original, rights-free or used with permission.

    Designer: Metroman

    Bridge Type: see construction notes

    Project Description: see below

    Poll: attached

    Images: attached



    DESCRIPTION


    Proposal: Portland Ivy Tunnel

    It is proposed that the bridge become a continuation of the CityPlace park, while replacing the unsightly view over the corridor with a green tunnel of ivy and its accompanying soft leafy sounds, and lush scent. The biological enclosure also assures that wildlife such as birds will make the bridge a home providing for an added natural atmosphere. Lighting will be achieved by hanging chinese-style paper lanterns strung along the tunnel. Finally, the enclosure of the bridge will limit the effects of the wind tunnel that is the rail corridor.

    Requirements & Limitations: To span over the rail corridor at a height satisfactory to CP/Via/GO and with the concession of a single pillar location. The bridge must be enclosed to impede tampering with passing trains below and to prevent would be suicide attempts.

    Original Proposed Landings:
    - SOUTH: Concord Adex owned and controlled
    - NORTH: City owned strip south of Front Street.

    The truss box proposal that was first advanced made use of the narrow city owned strip which proposed ramps perpendicular to the bridge to attain the height necessary over the rail corridor.

    Proposed Alternate Landings:
    - SOUTH: Concord Adex has complete control over a vast amount of land to the south where they're building a park (hereon referred to as "CityPlace Park"). They could landscape a hill with a soft sloping gradient meeting the required height, without the use of perpendicular ramps.
    - NORTH: By expropriating and converting the parking lot to the north of Front Street to a park (hereon referred to as "Portland Park"), the city could also build a soft sloping hill as the North landing which then follows a trail to Portland street.

    These alternate landings allow for:
    - No perpendicular ramps
    - A location for a second pillar on the city owned strip, permitting more creative options and more slack in engineering the bridge.
    - Accessibility to wheel chairs, bikes and rollerbladers with a softer incline/decline than the originally proposed ramps.

    Construction method:

    Phase 1
    The bridge is built in a lattice work of beams resulting in a round tunnel like structure. This structure can be built in small manageable sections, manufactured off site and easily carried by truck or rail to the site.

    While fabrication begins offsite, the two pillars are constructed with iron I-beams -- later to be surrounded by poured reinforced concrete. Provisions are made for temporary perpendicular beams to create a wide "T" shape. The edges of the T will provide a hookup for a tension cable that spans over the rail corridor to the corresponding T edge on the other side of the tracks. The same is done for the other edge of the T. These dual cables serve as a path to lay a net that will protect the rail corridor below from falling debris for the remainder of the construction process. This will allow for daytime work without danger to the fully operational rail schedule.

    Meanwhile,CityPlace Park and Portland Park prepare their slopes.

    The staging areas for assembly are the city owned strip on the north and the south landing in CityPlace Park.

    Once the lattice sections begin arriving, half of the bridge structure (minus walking platform, rails, etc) is assembled on the north staging area, while the other half is assembled on the south staging area. The goal is to only pre-assemble the barebones structure to maintain them light enough to lift with a crane.

    Once both sides of the bridge structure have been fully assembled, cranes on each end simultaneously raise their side of the structure, lowering one edge on to each pillar and secured. Both sections meet at the middle and are fastened together. Less than a 2 hour window will be required to achieve this safely at a time at which rail traffic is at its lowest -- such as late night.

    With the span made over the majority of the rail corridor, the remaining sections are crane lowered and put in place over Front St. to Portland Park on one end and over the remainder of the corridor to CityPlace Park.

    Phase 2
    A full tunnel is now in place but must be reinforced. This is attained by building a path of I-beams along the bottom/interior of the tunnel, branching at regular intervals with perpendicular V beams (2 diagonal beams forming a V) connected to the sides of the tunnel. The I-beams are first bolted in and then welded together to form a rail like path down the center of the tunnel from end to end. The bridge is now secured.

    Phase 3
    The rail like beam will serve as a platform to lay the walking path. Waist high rails will then be mounted along the sides of the tunnel. A fence is finally wrapped around the exterior of the tunnel. Below the walking platform rests a bed of soil from which ivy or climbing vines will grow, guided by the fence around the bridge in just a couple of years. Once the bridge is fully enclosed in the plants, the chinese paper lanterns (plastic used for durability) are strung along above the path, establishing a beautiful, relaxing and romantic new space in Toronto. It is expected that birds will build nests, adding yet another auditory barrier to the noisy trains. People crossing over will be blissfully unaware of the busy rail corridor below.

    note: the net and T cross beams may be removed once the bridge is built.


    IMAGES

    Satellite
    [​IMG]

    Cross-section
    [​IMG]

    Construction
    Image deleted - used without permission
    Designer note: This image is shown for structural demonstration only.

    [​IMG]
    Designer note: This image is shown as visual representation of the bridge. Details such as the walking platform *may be different. The Chinese lanterns are missing from this image.


    Additional Recommendation

    While the focus of this Design Charette is the Portland bridge, one could think of this project as a tri-bridge proposition. Fort York is in the process of designing a bridge over the rail corridor to Stanley Park, and Liberty Village is in need of a bridge over the same corridor to remove it from isolation by building a link to King St.

    The manufacturing of the structural sections could see a dramatic reduction in price for three bridges as one process rather than three bridges with separate budgets and different designs. The change for each bridge would be in its length (number of sections) while the design could remain the same.

    The city should consider this a single project to link the city to the waterfront over the rail corridor at multiple points with budgets split between Concord Adex, Fort York and the City of Toronto (a Liberty Village developer could contribute in exchange for density/height).
     
    Last edited: Jun 16, 2009
    #1

  2. Edward

    Edward Senior Member

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    Looks good.
     
    #2
  3. andomano

    andomano Active Member

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    Marks deducted for un-originality.
     
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  4. MetroMan

    MetroMan Senior Member

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    I'll take the criticism but you gotta credit me for thinking of the lot to the North. Everybody was focused on the tight strip of land south of Front St.

    Using the lot as a park and landing allows for two pillars instead of one and no use of perpendicular ramps.

    :)
     
    Last edited: May 15, 2009
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  5. ProjectEnd

    ProjectEnd Senior Member

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    Illuminating. Next time, please provide some more detailed feedback or risk having your comment deleted.

    On another note, FANTASTIC use of the parking lot to the north. This is an absolutely brilliant proposal which thinks both inside and outside of the box truss. I would never have thought to extend the bridge to the park, but now that I see how it could work, I can't get it out of my head.

    Great work MetroMan.
     
    #5
  6. Solaris

    Solaris Senior Member

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    great proposal ... definitely will be well received by the environmentalists ...

    however, I would be somewhat concerned in terms of:
    • lack of weather protection (vines don't deflect rain)
    • safety + security, it looks kind of scary in that tunnel, especially if you can see beyond the 'curve'
     
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  7. MetroMan

    MetroMan Senior Member

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    Weather protection wasn't a consideration for me. Most bridges in Toronto aren't weather protected either (think Humber bridge). The bridge leads from an open space to an even more open space (CityPlace Park). If rain cover was required for the bridge, by that logic, so would the rest of the park.

    I think the vines and leaves will considerably dampen the wind though. Also, in the winter, I could see the vines collecting snow and the bridge turning into a white winter wonderland. :)

    The curve is exaggerated in that photo. The view ahead would be much longer and to be honest, there doesn't need to be a curve at all. I just thought it added a little to the uniqueness of the design.

    My main considerations were having the landings be at ground level rather than use ugly ramps, replacing the view to the rail corridor with a much nicer environment with leafy sounds, birds and a lush scent. In essence, I wanted the bridge to be a natural continuation of the park.
     
    #7
  8. khristopher

    khristopher Senior Member

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    My biggest concern with this one is how it would look in the dead of winter. Grey vines covering a bridge might not look very nice.
     
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  9. W. K. Lis

    W. K. Lis Superstar

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    I must have missed the type of plants to be used. Are they evergreen or deciduous?
     
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  10. MetroMan

    MetroMan Senior Member

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    ^ I don't know of any evergreen vine. Are there any?

    The intention of this bridge is to be a natural, growing extension of the park. Like everything else in the park, in the autumn, the leaves change colour and eventually fall. In the winter, trees look bare but are made beautiful (in my opinion) with the snow that collects on the branches.

    The same would happen to the bridge.
     
    #10
  11. khristopher

    khristopher Senior Member

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    Snow tends to not stay on branches for very long, due to the warmth of the sun, so that beauty is very short lived :p
     
    #11
  12. Long Island Mike

    Long Island Mike Senior Member

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    Metroman's bridge design: Appropriate for a park but NOT for this placement...

    Metroman: This is a neat design but this would NOT work well for this application.
    With the plants growing around it and the curvature it may become a security problem. Cameras would have to be placed on it to police it.
    It looks to me that the walkway would not be wide enough and it would not be railfan or trainspotter friendly.
    This type of bridge is appropriate for a park overpass crossing a busy road or rail way and I feel that the curvature should not be there and that it be straight to allow good sightlines.
    LI MIKE
     
    #12
  13. TKTKTK

    TKTKTK Senior Member

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    I like this the best. The curve poses security issues, sure, so just straighten it out - the effect will still be really nice.

    Let's be realistic here, it's not going to be covered so densely with vegetation that you're not going to be able to see over the sides - but maybe some areas empty of vegetation are needed along the length for railfans (though couldn't they just do their watching from Spadina, or along Front Street, or one of the thousands of other rail vantage points in the city?)
     
    #13
  14. kEiThZ

    kEiThZ Senior Member

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    I love this concept the most...perhaps because it has greenery...

    I actually like the bridge/tube without the the green. Is there some way to have a half covered structure that is not overwhelmed with plant life?
     
    #14
  15. TylerBrown

    TylerBrown New Member

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    Nice structure, but closing it in with vines?

    Good rendering. I'm originally from Calgary (I.E cold for eight months of the year) and now I live in Vancouver. A big difference between Vancouver and places like Toronto and Calgary is that the latter two don't keep leafy plants green for much of the year. I can see a bridge like this working in Vancouver but not Toronto.

    By the way, the structure you have is quite interesting but the vine idea, not so much in a cold climate. Think about: maintenance, irrigation, view, and most importantly, what does the bridge look like for eight months of the year?

    And why close in a foot bridge to block a view?
     
    #15

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