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 [The combined contributions of several members of the New Zealand Railway Research Yahoo group, and Ferrymead archivist John Robb, have enabled Peter Ross to prepare the following notes. Readers are invited to correct him if he has erred in any way in his observations or in interpreting the various comments.]
Currently labelled Bridge 3 Main South Line, but originally referred to as Bridge No.1 (see alteration to drawing 1531), the Martindales Rd railway underpass is quite possibly the oldest extant railway bridge in the country, depending on how much original material remains of the up Opawa Bridge. It is also rare if not unique in having brick abutments.
It now seems fairly certain that the English bond brickwork was completed during 1865. The iron girder beams reported to be in Lyttelton at that time would no doubt have been set in place shortly after (Juliet Scoble, citing the Australian & New Zealand Gazette of September 2,1865). Prior to this there was quite possibly a temporary bridge over the gap to facilitate work on the embankment.
From the above, the bridge would have been used by the first goods train through the Lyttelton Tunnel on the night of November 19,1867, and the first passenger train on the morning of December 12,1867 (Juliet Scoble), and all traffic thereafter.
The beams have a span of 22 feet 6 inches (6.86 metres). Originally they carried a single broad gauge track, but on April 10, 1876 a 3ft 6in-gauge line was completed from Christchurch parallel to and south of existing the broad gauge. Through the tunnel its rails were laid inside the broad gauge on the same sleepers (The Country Commuter). By December 16, 1878 conversion to 3ft 6in had been completed and from then on the line from Heathcote to Christchurch was operated as double track (Ibid).
 The next known record is the undated drawing 1531. It carries the Engineer’s Office date stamps 18.09.02 and 14 May1929. A pencilled note across the middle reads: “Removed 1927 Bridge rebuilt RSJ now to 18938”. This tallies with last known record, an entry dated 1927 in what is now the OnTrack bridge database.
Many people had hitherto concluded that this was when the bridge was built, but we now know it dates from 1867.
What the note on the drawing seems to signify is that the beams were replaced in 1927, probably in preparation for the forthcoming electrification. The drawing shows the bridge deck was originally ballasted. It also shows chaired double-head rail on what had been the broad gauge track. The space between the beams matches the original gauges, suggesting that although the abutments appear to have been built with provision for a second track, the beams were only fitted when that track was actually laid.
Bridge No.3 Main South Line was recorded at 2m 15ch 50lks from Lyttelton until 1974 when the metric distance became 3.8559km (Gerald Petrie). An exact conversion to metric would have been 3.5304km, which indicates that at the same time the zero peg at Lyttelton was moved 325 metres east.
The bridge and abutments were built on a 30-degree skew to allow Martindales Road to pass straight underneath. Martindales Road (quite possibly Martindale originally, but now Martindales according to maps and street signage) was named for Robert Wilkinson Martindale (1831-1892) who arrived in Canterbury about 1863 and lived in the Heathcote Valley. He was a foreman to George Holmes, the contractor who built the Lyttelton tunnel (and almost certainly the bridge as well) (John Stephens, citing The Press, 29 September 1954, p16, and Juliet Scoble). (Note: According to Bill Pierre in Canterbury Provincial Railways, Martindale was actually the tunnel inspector.)
In the 1990s the Regional Civil Defence Lifelines Project identified the Martindales Rd Bridge, particularly the brick abutments, as being at serious risk in a major earthquake (J Robb pers com). It is not known if subsequent events are connected with this or the fact that incidents involving over-height trucks were becoming steadily more frequent and serious.
After significant damage to the down line beams c2000, this span was replaced, and a little later the abutments, which as already noted were showing signs of weakness and deterioration, were reinforced with engineering resin and large steel plates anchored into the embankment. When the replacement span suffered minor damage (it still bears the scars) soon after, strong steel and concrete protective barriers were erected just outside and a little lower than the bridge beams. Despite their bright yellow paint, these have seen their share of action but have so far fended off all further attacks – and bear the scars to prove it. They are also a target for taggers.
A more insidious threat than earthquake or trucks may be some Heathcote residents, who see the underpass as an inconvenience and a traffic hazard. Not counting the pedestrian way, the carriageway is only 4.9 metres wide and is thus restricted to one-way traffic. When the Heathcote Valley Community Association last enquired (about 2005) it was told there were no plans to replace the bridge, and for now the issue lies dormant.
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