Quote:
Originally Posted by ardecila
Said bridge would roughly be a mirror to the Orleans Street bridge, connecting River Point's elevated plaza to Wolf Point's elevated plaza and allowing pedestrians to pass above the Union Station approach and the river. I don't see why it needs to allow vehicles of any kind, except possibly the ride-on snowblowers the city uses. Presumably, maintenance would be performed by the landlords of each development. The aim is to provide a shortcut to Union and Ogilvie Stations while activating that corner of the West Loop.
A lift bridge seems easiest to build, since it doesn't need a huge pit for a counterweight. Here's one in Manchester of roughly the same dimensions that Chicago would need. Notice how it takes up very little land on either side. The towers could be designed to harmonize with the glassy aesthetic of the developments on each side.
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It's never been clear to me how the city would respond if one person or a large group of people, such as protestors, refused to get off a bridge when it was about to be raised. Between that situation, the need to clean and snowplow quickly and efficiently (e.g. just use the same streetsweepers used for adjacent streets) and keep bridge ice from forming, to make concrete or asphalt repairs (if those materials are used on the bridge), to do metalwork, lighting, or other repairs, or to respond to medical situations, it seems it would be just too useful in too many situations to forego having adequate girth for vehicles. Naturally, I am talking about emergency or other nighttime city work, not anything actually normally used for vehicular traffic. Besides, it might be a good place to run a bike lane or at least encourage people to walk their bikes across, especially if Kinzie doesn't work out well, so you'd want the width anyway.
In view of it being a bridge over a public, navigable waterway that must be ready to function to raise and lower on a specific schedule coordinated with all the other bridges, among other reasons, I don't think it would be realistic to have the private landowners handling maintenance or any aspect of running the bridge, other than maybe being subcontractors of the city for cleaning or similar limited services.
As far as a lift bridge goes - how much clearance is afforded by the lowest (or is it the only?) lift bridge on the South Branch?
Not to dwell on public disobedience too much, but a lift bridge could kind of invite urban scofflaws to try to "surf" the bridge while it is being lifted, and it would certainly allow bucket-beaters or other musical or panhandling, or benevolent or other, squatters to just leave their junk on the bridge while they temporarily evacuate during the lift. So if I were the city I might choose a bascule bridge, whose basic physics easily ensure the police need to be called in to intervene in far fewer situations. Granted, the bridges lift only infrequently, but having just 1 bridge-lift screw up the entire sequence of lifts could be quite a logistical mess because of the bridge tower teams and police that need to hopscotch down the river, not to mention the predictability to downtown's traffic and the vessels themselves waiting in a line in the river.