Duluth Aerial Ferry/Lift Bridge

Just 19 transporter - in the States known as aerial transfer or aerial ferry - bridges were built to completion worldwide, all between 1893 and 1916, except for one of 1938. Such structures were very much a European phenomenon; only one was ever constructed in North America, at Duluth, MI. (The Sky Ride built for the 1933 Century of Progress World's Fair in Chicago is often cited as a transporter bridge, but was in fact an aerial tramway.)

Duluth, at the western end of Lake Superior, is the largest inland port in the world. In 1870-71 the Duluth Ship Canal was cut through Minnesota (alternatively Park) Point, a seven mile long sand spit, in order to provide sheltered docks. Much of the spit was rendered an island. Ferries crossing the canal were unable to operate due to ice in winter, during which an inadequate suspension footbridge would be erected.

A 1891 competition sought a solution. The city decided to pursue one of the submitted proposals, for a vertical lift bridge designed by John Alexander Low Waddell, but the scheme foundered the following year due to objections from the War Department. Waddell's lift bridge was ultimately built, in 1894, but in Chicago, as the Halstead Street Bridge. A second competition sought a tunnel solution, but this idea sank too.

Meanwhile, between 1896 and 1902, the canal was widened and deepened. Thomas F. McGilvray, City Engineer at the time, inspired by the transporter bridges of Europe, in 1899 sketched one such, although of trussed rather than suspension form, as a way forward. The engineer C.A.P. Turner turned the sketch into a design, approved in 1901. The bridge had a main span of 393' 9", provided for a clearance of 135' above mean high water, and carried a gondola suspended by rigid steel hangers, instead of cables.

The foundations, built by Hugo & Timms, of Duluth, were completed by March 1902. However, funding difficulties with the American Bridge Company, and then steel supply problems affecting their subsidiary, the Duluth Canal Bridge Company, meant the bridge itself didn't proceed. DCBC's contract lapsed in May 1903.

Construction, by the Modern Steel Structural Company, of Waukesha, WI, finally commenced in July 1904. The first crossing of the gondola, 50 feet long, and 30 feet wide, took place on 23 February 1905. The crossing took about 1¼ minutes. Load-tested with 65 tons on 24 March, the bridge opened to the public three days later. The first car, an electric Studebaker Stanhope, crossed on 8 April.

However, as was the case with all transporter bridges, increased car ownership and usage rendered the bridge inadequate to demand by the mid-1920s. A redesign was undertaken in 1927 by John L. Harrington, of Harrington, Howard & Ash, of Kansas City. The solution was a lift bridge, remarkably similar to that designed by Waddell, with whom Harrington had once been a partner. The design was approved by the city in February 1927 and in January the following year received the blessing of Congress.

The contract was awarded to the Kansas City Bridge Company in February 1929, and work started the next month. The gondola crossed the canal for the last time on 1 July 1929. The re-engineering involved raising the towers 41 feet to accommodate the deck without compromising the 135' clearance, and strengthening them to carry the additional weight by building additional towers within the old ones. To avoid interruption to shipping, the 900 ton moving deck, counterbalanced by a 450 ton concrete weight in each tower, was constructed in the lifted position.

The converted bridge was first used on 12 January 1930. As ships and boats approach they blow a long-short-long-short signal on their horn, although lifts, which take just a minute, are largely radioed for about 1½ miles out. The signal is copied back by the bridge on its pair of Westinghouse Air Brake locomotive horn sets. There are about five thousand lifts per year. The bridge was added to the National Register of Historic Places in May 1973.

Rochefort Transporter Bridge

Frenchman Ferdinand Arnodin, with Spaniard Alberto de Palacio, was the patentee holder for the first transporter bridge design brought to realisation, just outside of Bilbao, Spain. Five transporter bridges were built in France, more than in any other country: at Brest (relocated from Bizerta, Tunisia), Marseille, Nantes, Rochefort, and Rouen; with a sixth commenced at Bordeaux but never completed. All were designed by Arnodin. Only the Rochefort bridge remains to France.

Crossing the Charente River, construction of the 700 ton iron and steel Rochefort Transporter Bridge commenced in March 1898 and was completed in July 1900. The towers, marked with Arnodin's name on each of the 16 shoes, stand 217 feet high, and the bridge has an overall length of 575 feet, with a main span of 459 feet at beam level. The beam is 26 feet wide and 154 feet above high water level. The suspension cables terminate in massive anchorages (below). The uppermost cables run back to additional anchorages built in 1933 when the bridge was converted from being predominantly cable-stayed to being entirely of the suspension form.

The gondola, 48 feet long and 38 feet wide, was originally moved under steam power, with electric motors taking over in 1927. It could carry 14 tons - either nine horse-drawn carriages plus 50 pedestrians, or 200 pedestrians alone. The crossing took four minutes. The boom was rebuilt in 1933-34, changed from Arnodin's open lattice to a solid-sided plated form. The gondola was uprated to carry 16 tons. This last was dynamited by the Germans in 1944, but subsequently replicated.

The bridge was abandoned in February 1967 upon opening of a nearby vertical lift bridge, itself demolished in 1991 after opening of the Martrou viaduct road bridge (in background of first photo). Funds were put aside in 1975 for the bridge's demolition, but it was declared an historic monument in April 1976, and refurbished between 1990 and 1994.

The bridge is normally open in the summer months for use by pedestrians and cyclists. At the time of writing it has been closed for a predicted three year period, to replace the boom with one constructed much more closely in accord with Arnodin's original design, and to revert to the original largely cable-stayed format, at an estimated cost of £27 million. There is a good museum on the Échillais (Martrou) side of the river.

Bilbao - Transporter Bridge

Puente Vizcaya, just outside Bilbao, and connecting Portugalete and Las Arenas, is the oldest transporter bridge in the world, the first of just 19 built to completion worldwide, and the only one built in Spain.

The bridge was designed by Spaniard Alberto de Palacio and engineered by Frenchman Ferdinand Arnodin. Construction commenced on 10 April 1890, and the bridge officially opened on 28 July 1893. The influence of the Eiffel Tower of 1889 is obvious.

Built of iron, it has a span of 525 feet, with towers 200 feet high and of 100 tons each, braced by cables that run parallel to the River Nervión. The original boom, gondola and traction gear weighed in at a further 400 tons. The bridge is joined together by 21,401 bolts and 10,629 rivets. The tower on the Las Arenas side housed a coal lift.

The truss was dynamited on 17 June 1937, during the Spanish Civil War, but service recommenced in June 1941, with a lighter boom and larger but lighter gondola. The bridge received in November 1998 its fifth gondola. This hangs from a 36-wheel trolley, is 82 feet long, and can carry six cars and 200 people at a time (bottom).

Still very much in use, operating every eight minutes during the day, every hour during the night, the journey taking just 90 seconds, the bridge is integrated into the ticketing for Bilbao's wider public transport system. Until 1999, except for a period 1941-45 when controlled from the gondola, it was operated from a booth up on the boom (above).

The 1998 overhaul included construction of ground-level waiting rooms and an enclosed walkway, with lifts at both ends, that enables one to walk across the river at about 147 feet above high water level (above). Known locally as the Puente Colgante, the Hanging Bridge, this world first was declared by UNESCO in July 2006 a World Heritage Site.

Rendsburg Transporter Bridge, Schleswig-Holstein

The Rendsburg High Bridge was the last of the three transporter bridges built in Germany: Osten opened in 1909 and remains in use, Kiel opened in 1910 but was demolished in 1923, and Rendsburg opened in 1913 and remains in use.

Designed by Friedrich Voss, construction began in 1911. The bridge was, and is, unique, in that it is properly a railway viaduct, carrying the Neumünster-Flensburg line over the Kiel Canal. From the central bridge (above) is slung a gondola such that the structure doubles as a transporter bridge.

Because the bridge carries a railway, a maximum incline of 1:150 was required. Accordingly, the whole structure is about 4.7 miles long, including the approach embankments. The trussed steel viaduct (first and last photos) boasts a total length of 8,156 feet, an incredible 1.5 miles.

The cantilevered central bridge is 966.5 feet long and has a main span of 459 feet. The towers are 164 feet high, and the bridge provides clearance above the canal water of 138 feet. A design quirk of the viaduct is that on the north side of the canal the 360-degree Rendsburg Loop carries the railway down to Rendsburg Station, at ground level.

The transporter bridge operates daily, making it one of just seven bridges worldwide still operating in transporter form. The journey between Osterrönfeld and Rendsburg takes just 90 seconds, and is repeated every quarter of an hour.

Regrettably, the gondola, which can carry four cars, but is largely used by pedestrians and cyclists, was in January 2016 struck by a cargo ship and badly damaged (above). At the time of writing, the transporter bridge was as a result not operating.

Osten Transporter Bridge, Lower Saxony

Osten Transporter Bridge was built 1908-09 to provide a crossing between Osten and Hemmoor that did not interfere with shipping on the River Oste. It is one of only 19 transporter bridges ever built to completion worldwide, and was the first of three in Germany: Osten (in use), Kiel (opened 1910, dismantled 1923), and Rendsburg (in use).

With a span of 259 feet, and a width of 32 feet, the bridge is of truss construction. The structure is symmetrical but for the overhang on the Osten side of the river (below).

Unusually for a transporter bridge, the gondola (next two photos) is suspended from the moving trolley by way of solid steel latticework, instead of the usual cables. Large compared to the modest scale of the bridge, the gondola can transport either 100 people or six cars at a time.

The foundations were laid by a local constructor, and the steelwork was fabricated by MAN (Maschinenfabrik Augsburg-Nürnberg) at Gustavsburg. AEG (Allgemeine Elektricitäts-Gesellschaft) of Berlin undertook the work to provide electric traction, as in a tram.

The bridge operated on a regular basis until 1974. It was listed as a Technical Monument in 1975. Taken out of service in 2001 because of extensive rust damage, the bridge was recommissioned in 2006.

Now operated as a tourist attraction from April to October, Osten is one of only nine survivors from the 19, and of only seven transporter bridges still operational in their original form. A small museum devoted to the bridge can be found on the Osten side.

Warrington - Transporter Bridge

Of the 19 transporter bridges built to completion worldwide the UK boasted four: Newport (operational), Middlesbrough (operational), Widnes-Runcorn (demolished 1961-62), and Warrington. Warrington (also known as Bank Quay) Transporter Bridge was commenced in 1913 and opened in 1916. It linked two parts of the Joseph Crosfield and Sons Ltd chemical and soap works, either side of the Mersey.



















Designed by William Henry Hunter and built by Sir William Arrol & Co., the bridge has an overall length of 339 feet, a span of 200 feet, is 30 feet wide, and has a height above the high water level of 79 feet. The cantilevered truss structure is founded in massive concrete caissons, faced in engineering brick. These, and the heavy double cantilevers to each of the four towers, shout the industrial use.

The bridge is alternatively known as Crosfield's No.2, as there was another 'bridge' on the site, slightly further north. Built 1905-07, and in service from 1908, Crosfield's No.1 is oft-cited as a transporter bridge, yet there is no evidence that it ever carried a gondola, which disqualifies it from the club. It was, in effect, a gantry crane. The trolley of No.1 was removed by the time of WWII, and the structure was demolished in the 1960s.

Warrington (Bank Quay, Crosfield's No.2) Transporter Bridge is a unique survivor worldwide, in that the gondola was constructed to carry railway stock. The only other example that did so was the Kiel transporter bridge, demolished in 1923. The rails continued right up to the edge of the aprons either end of the bridge (above) and onto the gondola, and can still be seen in the adjoining east bank chemical works yard. The gondola was converted for dual rail and road vehicle use in about 1940, and strengthened circa 1949 to increase the carrying capacity from 18 tons to 30 tons.

The bridge ceased operations in about 1964, and now stands in a very dilapidated state, the gondola stranded on the inaccessible west bank. Despite being scheduled as an ancient monument, Grade II*-listed, and included on the Heritage at Risk Register, the bridge has been left to rot, a victim of its Warrington Borough Council ownership.

Middlesbrough's Tranny

19 transporter bridges were built to completion worldwide. Of those, four were in the UK: Newport, Middlesbrough, and two over the Mersey (one at Widnes, and one at Warrington). Three of the UK transporter bridges remain, at Warrington, Middlesbrough and Newport, of which the last two are still operational.

Connecting Middlesbrough, south of the River Tees, to Port Clarence, to the north, the Tees Transporter Bridge boasts an overall length of 851 feet and a span (between the towers) of 590 feet. Longer overall than its Newport cousin, although with a span of 56 feet less, the bridge is the longest remaining transporter in the world. (The longest ever built was that between Widnes and Runcorn: it had a span of 997 feet and was 1,150 feet long overall. It was demolished 1961-62.)

Commonly called the Middlesbrough Transporter Bridge, and known locally as The Tranny, the bridge was designed by the Cleveland Bridge and Engineering Co. Ltd, of Darlington. It was built between 1909 and 1911 by Sir William Arrol & Co., of Glasgow, famous for construction of the Forth Bridge.

The bridge is of cantilever form. The structure employs 2,600 tons of steel, plus another 600 tons in the caissons. This compares with 1,326 tons for the more elegant, wider-span, Newport bridge, which relies on its suspension cables for much of the necessary tensioning.

Still operating six days a week, the bridge was Grade II* listed in 1985, with the winch house, piers, railings and gates separately listed Grade II. The third gondola was installed in 2011. Suspended from the truss, which is 160 feet above high water, this can carry nine cars and 200 people, and crosses the river in just 90 seconds.

Newport - Transporter Bridge

Newport Transporter Bridge is one of only 19 such bridges ever built to completion, worldwide (counting only once the bridge at Bizerta that was rebuilt at Brest). It was one of four built in the UK. To properly qualify as such, a transporter bridge must be a high-level structure that carries a gondola suspended at grade, and leaves the crossed waterway unobstructed. As such, these bridges can be better thought of as aerial ferries. The first working example, Puente Vizcaya, was opened in 1893, between Portugalete and Las Arenas, near Bilbao, Spain, designed by Spaniard Alberto de Palacio and engineered by Frenchman Ferdinand Arnodin, patentee holders.

The Newport aerial ferry was designed to enable workers from the city, on the west side of the River Usk, to reach the developing industries on the east side, without an eight mile round walk. A ferry had operated nearby, but the extreme tidal range made use impossible at low tide. A conventional bridge would have required very long approach ramps to provide for ships to pass beneath, and tunnelling would have been too expensive.

The Borough Engineer, Robert Haynes, arranged for the council to visit the transporter bridge at Rouen, France, opened 1899. The Newport bridge received parliamentary approval in 1900. Arnodin undertook the design, and he and Haynes were appointed joint engineers. The contract was awarded to Alfred Thorne, and the Cleveland Bridge and Engineering Company. Work commenced on site in 1902, and the bridge opened in September 1906.

The high-level boom, 774 feet long and with a main span of 646 feet, is slung between towers, the tops of which are 243 feet above road level. Rail tracks are carried by the boom, and upon these runs a traveller. In turn from this is suspended a gondola (second photo), pulled across the river at ten feet per second by a continuous cable, the winding of which is powered by two 35 horsepower electric motors. The winding house is situated at the eastern end of the bridge (below). The 1,326 ton steel structure is of the combined suspension and cable-stayed form, a series of three-inch wide suspension cables carried over the top of the towers. The anchorages are each formed of over 2,200 tons of ashlar, their centres 1,545 feet apart.

Grade I-listed in 1982, the bridge was closed in 1985 due to safety concerns. It cost circa £98,700 to build originally, and £3m to refurbish. It re-opened in 1995, only to close again in 2008. A further £1.23m of work enabled the bridge to operate once more from July 2010.

Just nine of the 19 bridges survive. Of these, seven are in use in transporter form: Puente Vizcaya in Spain; Rochefort in France; Osten and Rendsburg in Germany; Newport and Middlesbrough in the UK; and Buenos Aires in Argentina. An eighth, that at Duluth, Minnesota, USA, although still in use, was converted to a lift bridge, reopening as such in 1930. The one other survivor, at Warrington in the UK, lies derelict.