Tower Bridge was designed to reconcile the conflicting interests of road and river traffic at a time when London was the world's most populous city and also its greatest port.
But before the globally famous design we know today was chosen, a host of eminent Victorian architects and engineers proposed some very different solutions to the problem of allowing increased road traffic without impeding large vessels on the river.
In 1876 designs for a new Thames crossing were invited by the Corporation of London. F.J. Palmer submitted this plan in 1877.
Palmer's bridge, inspired by earlier designs, had two moveable platforms at either end of the bridge and it was intended that at each one a roadway would always be in place, even when vessels were passing through.
Sir Joseph Bazalgette, chief commissioner to the Metropolitan Board of Works, proposed a series of designs for a very high-level bridge that would have allowed shipping to pass beneath.
As the architect of London's great sewer, the Victoria & Albert Embankments, Putney, Hammersmith and Battersea bridges and much else, Bazalgette's proposals were perhaps the most credible of the 50 different designs submitted.
But all three of Bazalgette's designs would have required an enormous spiral ramp on the southern bank of the Thames to enable traffic to descend at a reasonable gradient.
Other proposals included:
Various other low-level bridges with openings in the roadways.
A low level bridge with an uninterrupted roadway ( not acceptable to shipping and wharf owners).
A high-level bridge with hydraulic lifts to raise and lower traffic.
A tunnel with hydraulic lifts and a tunnel with inclined approaches.
A ferry (seen as impractical on account of delays caused by fog and frost).
In 1878 Horace Jones, Chief Architect and Surveyor to the Corporation of London and one of the judges on the panel assigned to choose the final design, must have been pleasantly surprised to discover that his own design for a low level bridge with twin drawbridges (bascules) was considered to be the front runner.
Glasgow based engineers Bell & Miller were not happy with the officially sanctioned Jones design and introduced their own Bill into Parliament in an attempt to build their design for a "duplex" bridge.
Bell & Miller's Bill failed and so this gigantic pair of "locks" closed by swing bridges and set into a hexagonal roadway were never built.
Instead, in 1886 work began on the Jones plan, after substantial revisions made in collaboration with James Wolfe-Barry. Jones died one month into the construction and so it fell to Wolfe-Barry to complete the bridge in its current form (Jones had wanted to clad the steel structure in brick rather than stone).
Eight years, and the loss of ten lives, later, Tower Bridge opened in all its steel and stone magnificence on the 30th June 1894.
All the above images come from an original copy of The Tower Bridge - Its history and construction from the date of the earliest project to the present time by J.E. Tuit published by The Engineer, London, in 1894.The book contains many other potential designs as well as building plans for the bridge and images of its construction.
This is a rare book and a copy will set you back around £100-£150 but it has been scanned and uploaded by Unz.org so you can read it for free here.