Competitors in the Five Bridges River Swim in the Waikato River, on Sunday, April 3rd 2011, will view a wide range of huge Hamilton bridges from underneath during their 6km journey from Hamilton Gardens to Ann Street Reserve.

First up is the Cobham Bridge, at the western end of Hamilton Gardens. It was designed and constructed by the Ministry of Works as part of the State Highway 1 network and opened on June 29, 1963. It has concrete piers, a steel undercarriage and concrete decking.

The proscenium arch of the Victoria Bridge heralds the start of the central business district on the west bank. This structure replaced the Union Bridge, which had been built in 1879 to unite the small riverside communities of Hamilton East and Hamilton West into one borough. The Victoria Bridge, originally known as the “Hamilton Road Bridge”, opened for traffic in September 1910. The engineer was J. E. Fulton, of Wellington, the builder was G. M. Fraser and the contractor was W. T. Johnson. The Cleveland Bridge Company of England provided the steelwork. This is the bridge’s centennial year, with celebrations planned for September.

The Claudelands Bridge is the oldest engineering structure on the river-swim course. Originally it was a rail bridge, completed in July 1883. It was strengthened in 1908 and 1936 to take heavier trains. When the railway crossing on Victoria Street became too much of a hindrance to city traffic in the early 1960s, a rail tunnel was built under the central business district. This was linked to a new concrete rail bridge, built in 1964 to the north and just below the height of the old bridge. After the last train used the Claudelands Bridge in 1965, it was converted for road traffic by removing the tracks and attaching a steel deck. When viewed from underneath by river-swim competitors, the structure reveals the combination of civil engineering styles that make up its colourful 127-year history.

In contrast, the Whitiora Bridge is a modern, svelte structure, made of reinforced concrete. It opened in February 1978 as a two-lane bridge. The consulting engineers were Murray-North Partners Ltd and the contractors were Rope Construction Co Ltd. Today it carries three lanes of traffic on its original decking, as evidence of Hamilton’s recent growth in traffic volumes.

The final engineering marvel on the river-swim course is the Fairfield Bridge. This reinforced concrete structure with its distinctive three arches was completed and opened in March 1937. The designers were Jones and Adams, of Auckland, and the builders were Roose Shipping Co Ltd of Hamilton. When it was built, Hamiltonians complained that it was too far out of town, the Never A Dull Moment exhibition at Waikato Museum reveals. But the city spread quickly to the north during the post-war years.

Competitors in the river swim will also gain a fascinating glimpse into why Hamilton is sited where it is.

The Waikato River course, from Hamilton Gardens to the Ann Street Reserve in the suburb of Beerescourt, is mostly lined with lush, steep riverbanks.

Before the wars of the 1860s, Maori had used the river as a quick transportation route by canoe between their Waikato landholdings.

When British troops landed near the deserted Maori village of Kirikiriroa in August 1864, they built redoubts on the western and eastern banks. The troops knew that whoever controlled the high banks controlled the river. The 4th Waikato Militia established a military township there in 1865, naming it after Royal Naval Captain John Hamilton, who was killed during the battle of Gate Pa, in Tauranga, in 1863.

Hamilton West was established at the bottom of Grantham Street and Hamilton East was sited in Grey Street. A punt service connected the two settlements, until the Union Bridge was built in 1879, near where today’s Victoria Bridge crosses the river.

Swimmers will discover that this is the only part of the 6km Five Bridges River Swim course where both sides of the riverbank were low enough to allow easy transportation by punt across the river during the early days of European settlement.

For much of the river swim’s route, the banks rise to the height of a 10-storey building, which would have given occupying British troops a military advantage over Maori warriors in their canoes.

In Alison Drummond’s Early Days In the Waikato, she explains how Hamilton’s early European settlers were fearful of reprisals from Maori:

“The bugles might sound a retreat to the redoubt at any time; the men would stand to arms, and women gather up their children, snatch the washing from the line and, with as much of their scanty possessions as they could carry, go to the shelter of the stockade. No attack came, thought there was always considerable speculation on the plans of the Maoris.”

River-swim competitors who take the time for an occasional breather on April 11 will learn a lot about Hamilton’s unique geography and why the 4th Waikato Militia chose that strategically important site for their military township after the wars.

The entry form for this year’s river swim is available from swimming pools, gyms and sports shops. When available it can also be printed from the New Zealand Masters Swimming website.