There are areas where there is a possible need for a pedestrian bridge over a busy road. Not everywhere is either suitable or long-term enough for a conventional bridge to go in.
This idea is for a semi permanent rope bridge to be slung from reinforced lamp posts at either side of the road to enable suitably keen people to cross there. Access to the bridge would be via ladders attached to the lamp posts.
It’s not an ideal solution as only the fit and agile would be able to use it, but it’s better than no crossing at all.-- oneoffdave, Jan 19 2005 Interrobang http://en.wikipedia.org/wiki/InterrobangHow did I miss this word?! [calum, Jan 19 2005] The Indian Rope Trick http://skepdic.com/indianrope.htmlPeter Lamont's investigation into the rope trick. [oneoffdave, Jan 20 2005] (?) Tufty Bridge http://www.highways...eral/2004_02_27.htmHelping squirrels cross the road. [oneoffdave, Apr 14 2005] Pygmies build bridge https://www.youtube...PYvaA0Lz70A&t=2m16s [pashute, Apr 13 2015] The Abernathy footbridge http://www.ngcc.org...3D&tabid=84&mid=456A lighweight footbridge in Scotland. See anno. [CraigD, Apr 27 2015] Oops! Corrected now. Should have known better as I was reading 'Eats, Shoots and Leaves' last night. Nice mentions of the 'bakery and the interrobang.-- oneoffdave, Jan 19 2005 Why not just put a normal bridge across the road? Expense or something?
Also vandals would cut the rope. The wooden slats risk rotting. Wood gets slippy in the wet. The ladders would be nicked. the rope bridge would stretch in time, getting dangerously low. Kids would use it as an adventure playground. People not able to easily climb the ladder would try anyway. Discriminatory. Wobbly so more people likely to fall off them. Ladder would make accidents more common as people fall down them. Easier for muggers, who know escape routes from the bridge are slow and cumbersome. During high winds people would fall off. A car hitting the ladder accidentally could leave people stranded. There would have to be a safety limit for number of people on the ladders at the same time (as ladders are not as good as concrete). The rope would rot. The ladder rungs would become slippy or rot. Yobs would purposefully rock the bridge as people tried to cross. Pervs would look up girls skirts between the slats as they tried to cross. Pervs would look up girls skirts as they climbed the ladders. Pickpockets would find good opportunity to work as people scaled the ladders. If someone had a medical illness on the rope bridge it would not be easy to get them down or get medical attention up there. The weight capacity would not be as good as for concrete bridges.
But apart from that. +-- britboy, Jan 19 2005 I like it, but I think it would be more fun if you just installed a zip line.-- scad mientist, Jan 19 2005 Do rope bridges *really* count as a new idea...? They've been around for quite a while now.-- DrCurry, Jan 20 2005 Although referred to as a rope bridge, the structure would actually be constructed of heavy duty wire rope. The ladder would be welded to the lamp post. This is only a very temporary structure desgined for short-term use.
A 'proper' bridge costs in the region of £2-3m and can take 3-6 months to build.
As far as the discriminatory nature of the bridge, as stated in the original idea, it's not an ideal solution as it was never intended to be.
Some of the issues raised are also common factors with 'conventional' foot bridges. After every vehicle/bridge impact they have to be inspected by a civil engineer. A lot of footbridges in the Uk aren't yet reinforced enough to survive an impact with the larger heavy goods vehicles allowed on the road.-- oneoffdave, Jan 20 2005 To be even more discriminatory, put up tight-ropes over busy roads. Then only circus performers could cross.-- robinism, Jan 20 2005 [Dr Curry] The rope bridge part of this wasn't really the idea. What was, was using them in an urban setting as a method (albeit limited) of crossing roads.-- oneoffdave, Jan 20 2005 I would have liked this better if it were a pneumatic tube that sent people over. Thup!-- ldischler, Jan 20 2005 An arched rope bridge via an Indian rope trick would be neat.-- FarmerJohn, Jan 20 2005 It seems this idea has now been implemented for squirrels in Lancashire [link]-- oneoffdave, Apr 14 2005 //Pickpockets would find good opportunity to work as people scaled the ladders// that's one very nimble pickpocket-- scubadooper, Apr 14 2005 Tarzan swings, and a big vertical catch-net? [+]-- AbsintheWithoutLeave, Apr 14 2005 Pygmy bridge. See link-- pashute, Apr 13 2015 [+] The idea. I think lightweight bridges are underappreciated and used.
My first thought on reading this idea was of the Aberfeldy footbridge (see link), a 14500 kg (light!), quite comfortable, 63 m main span fiberglass (GRP) and Kevlar cable suspension bridge. It uses A-shaped 18 m fiberglass pylons, about twice the height of a typical light pole, but I don’t see that adding a lightweight, stayed extension to a light pole would be showstopper.
The Aberfeldy footbridge has fiberglass decking. Though it’s denser, I think it’d be extra-nifty to use recycled plastic decking. This stuff can be extruded in a hollow- cored section that I’ve a hunch could be as stiff as and weight as much or less than the solid fiberglass used at Aberfeldy, and is a better endpoint in the plastic waste stream than the usual landfill.-- CraigD, Apr 27 2015 random, halfbakery