Irish Railway Bridges-3

NIALL V. TORPEY C.Eng, F.I.Struct.E, F.IEI

CONTINUING DEVELOPMENT

The years 1865–1925 It is perhaps appropriate to consider the relatively long period of some 60 years, which saw the culmination of the halcyon days of the private enterprise of railway ownership, to be followed almost immediately by the significant political changes and Government involvement in the administration of the railway business in Ireland. This period was the one in which the last public railways were built in the country. These were the Rosslare Harbour – Mallow development in 1902-6, which involved the construction of the longest railway bridges in the country. Other railways built to help the WW I war effort involved the lines from Athy to the Wolfhill Colliery and to a similar facility above Castlecomer. The Wolfhill line is notable as the site of the first use of reinforced concrete as the superstructure material in underbridges over the river Barrow at Athy and in the hills up to Wolfhill.

Events on the railways in 1916-1923  The Rising of 1916 broke out at about noon on Monday, 24 April. At 1 pm on that day the GS&WR received orders from the military to provide four troop trains, capable of conveying 2,000 troops from the Curragh to Dublin. Empty trains to cater for this order left Kingsbridge at 1.10 pm, 1.40 pm, 1.55 pm and 2.10 pm. No civilian trains left Kingsbridge after 12.20 pm. A further two empty troop trains left Kingsbridge at 8.25 pm and 8.50 pm to collect a further 1,000 soldiers from the Curragh. Late on the evening of the same day another special carried 200 officers and men from Cork to Mallow to protect the Blackwater Viaduct there. Many other unusual workings took place at this time such as non-stop specials, and passenger workings between companies’ lines.

Damage to the railways in 1916 was modest, being mainly confined to the occupation some of the principal Dublin stations for a part of the period of the rebellion. Thus, Westland Row station of the D&SER was closed to traffic by some of the garrison at Boland’s mills, and Harcourt Street station was also closed but in this case only for a few hours. The GNR(I) line was interfered with by rebel action at Rogerstown viaduct when a bomb was placed against the ironwork of the bridge. The event was reported in The Irish Times of Tuesday 25 April, 1916 as follows:

Shortly after 3 o’clock in the afternoon an attempt was made to blow up the … bridge at the inlet of the sea… at Rogerstown. The bridge is in sight of the Donabate station, and a few minutes before the 2 pm train from Dublin was due in Donabate the stationmaster heard a loud explosion. At first he thought the sound came from blasting in the quarries which are close by, but the smoke was immediately apparent over the …bridge. The stationmaster and some of the men on duty ran there as fast as they could, and found that an attempt, which was fortunately unsuccessful, had been made to blow up the middle section of the bridge…

In the later period of the troubles, the amount of damage caused to the rail network was small enough, until the start of the Civil war in the summer of 1922. Between then and the war’s nominal end about a year later, much damage had been caused to the engineering infrastructure of the railways, particularly to bridges and signalling. In the case of bridges, damage and destruction was concentrated in the NE, SE, S, SW, and W of the country. In this period, the Ballyvoyle viaduct was destroyed and Monard viaduct was severely damaged, but repairable.

TWENTIETH CENTURY DEVELOPMENTS

The years 1925–1965 The financial effects of the Great War and the immediately subsequent Troubles and the Civil War resulted in a large amount of necessary bridge repairs and rebuilding. This placed even the most commercially successful companies under almost impossible financial strains. In order to ensure the future of the railway network, the Free State Government arranged for the amalgamation of all the railways within the Free State into one company, called the Great Southern Railways. The difficulties caused by the Border with the new state of Northern Ireland resulted in the Great Northern Railway Ireland and some other minor lines straddling the Border being left out of the Free State’s amalgamation. Further general difficulties caused by competition with road transport began about this time and continued up to the end of this review, and indeed beyond.

As far as railway bridge works are concerned, the general financial constraints had a serious adverse affect on the ability to renew bridges and a make-do-and-mend approach seems to have pervaded the network. The effect of this was to cause many heartaches to those charged with maintaining a railway network which could not be funded from earnings, and which Governments were increasingly reluctant to fund from general taxation. It is appropriate to record the appreciation that is due to those engineers and others who in such a hard financial climate managed to keep a public railway running, whether from the point of view of motive power, or the engineering infrastructure. However, an amount of necessary bridgework was undertaken. In the period up to about 1940, most renewals were carried out using structural steelwork, in many cases supplied from Britain, and in not a few cases using salvaged bridge materials from closed lines.

The period of WW II was of course one of extreme shortage of materials of all kinds, and in our case of bridge building materials. However, a distinct emphasis on the use of structural concrete is discernible at about this time. This was to continue and to become a normal material for bridge renewals, at least south of the Border. In the earlier days of its use, delays caused by concrete setting and hardening resulted in its use being restricted to overbridges, where the closure of lines could be avoided. The use of pre-cast concrete also emerged particularly for underbridges, but the difficulties caused by the limitations of rail mounted steam cranes to lift heavy pre-cast concrete units into position made it difficult to adopt for other than smaller bridges and culverts or at least for liftable pre-cast concrete sections.

In the case of the use of structural steel, 1957 saw the last example of riveted construction at the Quagmire viaduct on the Mallow-Tralee line. The following year saw the first example of an all-welded bridge carrying the Dublin-Belfast railway over the North Wall branch.

As a subset of reinforced and pre-cast concrete, the first use of pre-stressed concrete bridge beams for railway use can be shown to date from about 1943, when such beams were used in wartime Britain by the LNER and the LMSR on spans of 50ft and 42 ft respectively²³. In Ireland pre-stressed concrete was used for the renewal of OB 56 near MP 22 south of Sallins in the early 1950s to the design of L. F. Stephens. A little later in the same decade, pre-stressed concrete was again used, this time by the GNRB, in the renewal of the under-bridge over the river Tolka and East Wall road which had been destroyed in severe flooding on 8 December 1954. The new bridge was brought into use on 12 January 1956, and the temporary Bailey bridge in use from 4 January 1955 was removed on 19 January 1956. In November 2002 this early Irish pre-stressed concrete underbridge was itself replaced, to allow for an increase in both road and rail traffic²⁴. An interesting use of pre-cast concrete units, stressed together, was at the construction in 1956 of the pedestrian access tunnels to Lansdowne road Rugby ground under the Dun Laoghaire railway. Pre-stressed concrete is the material, which has emerged as an important structural material for railway bridge renewals in the period up to the end of this review and indeed beyond.

CONCLUSION

I have already noted that for much of the time covered by this review, the financial condition of the railways was difficult, and this inevitably reflected on the business of maintaining the railway and its various parts, including its bridges. Many forces at the time, for example the Beddy Report, were leading to the demise of railways altogether, or at least their serious curtailment. In Northern Ireland, such forces held much sway in Government with the resultant loss of much of the network there and the serious running down of what remained in preference to the construction of the first motorways in Ireland. That engineers and others, in spite of these influences, maintained a public railway network is surely a matter for quiet satisfaction.

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