Category Archives: Engineering and construction

Skew arch bridges

The IHAI AGM at the weekend, in Newtownabbey Borough Council’s splendidly restored Mossley Mill,  included a tour of the premises and its museum. Then Professor Adrian Long of Queen’s University Belfast gave a short talk about the FlexiArch bridge, which his team have been developing since the 1990s.

Professor Adrian Long with a wooden model of the FlexiArch bridge

He said that their work started by asking why nobody built arched bridges any more; they developed a system that used pre-cast voussoirs (the wedge-shaped blocks) linked by a polymeric flexible membrane. The voussoirs for any bridge are cast to give the correct taper for the span and rise required for that bridge.

Arch rings arrive on site stowed flat on the back of a truck; when they are lifted off, they fall into the correct shape and are lowered into position on previously-installed footings. Each arch ring is 1m wide; several of them can be placed side by side to give whatever width is required. The end walls are added and the structure is filled and given the appropriate surface (eg tarmac).

FlexiArch is manufactured by Macrete of Toomebridge (beside Lough Neagh); their website shows several examples of installation including one at a name familiar on Irish waterways. There is a brochure [PDF] and there is a video showing the installation of a 15-metre bridge.

Wooden model as a skew arch

No, I haven’t any shares in it. I just thought it was interesting, for three reasons: first, the speed of construction is very impressive; second, there is a link to Lough Neagh; third, it might encourage the construction of more skew arch bridges over canals.

 

Dry docks

GRAND CANAL

At a Meeting of the Company of Undertakers of the Grand Canal, duly convened by public Advertisement, and held at the Company’s House in Dublin, on Monday, the 6th day of April, 1840,

WILLIAM MURPHY, Esq., in the chair,

The following Resolution, moved by James Pim, jun., Esq., seconded by James Dawson, Esq., passed unanimously in the afformative: —

Resolved — That the Court of Directors of this Company be authorised, if they shall see fit, to call the attention of the Government, of the Chamber of Commerce, of the Ballast Corporation, of the several Steam Companies, and of Capitalists generally, to the important advantages which the Grand Canal Company’s Floating and Graving Docks at Ringsend offer to all parties connected with the Shipping interests of the Port of Dublin, and to apprize them that this Company will at all times be ready to entertain any well considered proposition for increasing the general usefulness of these Docks, on the fairest and most liberal terms as regards the Public. Under the firm persuasion that by whatever well-arranged proceeding this important portion of the Company’s property can be best made available in increasing the Trade and promoting the prosperity of the City of Dublin, it will be rendered the most effectually conducive to the interests of the Company.

By order, JOHN McMULLEN,
Secretary of the Company.

From The Freeman’s Journal 8 April 1840.

Perhaps Waterways Ireland might follow the example of its predecessors and, rather than getting into bed with the DDDA, might consider some “well considered proposition for increasing the general usefulness of these Docks”.

 

The sluice house at Lough Owel …

… has had its windows broken. More on the Lough Owel Feeder here.

Dublin or bust

If you’re not already a reader of Barge Hawthorn’s blog, may I suggest that you start now? The account of the descent into Dublin along the Royal Canal, over three days, features mounting tension, a really superb photo of the M50 aqueduct and a happy ending when Effin Bridge lifted when required.

You can work your way backwards through earlier posts to find the how and the why.

Lough Neagh

On 17 April 2012 the Northern Ireland Assembly held an enlightening debate about Lough Neagh and its future and ended by resolving

That this Assembly calls on the Minister of Culture, Arts and Leisure and the Minister of Agriculture and Rural Development to convene a working group to explore and pursue actively the potential for a cross-departmental approach to bring Lough Neagh back into public ownership.

The report is here. It is well worth reading by anyone wanting an understanding of the management of the largest lake in These Islands.

 

Impartial amusement …

… but surely floe, not flow?

Royal water

Here is a page about feeders to the Royal Canal. My confidence in the accuracy of this list is low, so comments would be welcome.

Grand water

Here is a page about the feeders that supplied water to the Grand Canal. There will soon be a page about the Royal Canal feeders; these will lead to an examination of the current and proposed supply of water to the Royal.

Mullingar dry dock(s)

The Ordnance Survey map of around 1840 shows a dry dock at Mullingar:

Mullingar dry dock ~1840

So does the map of around 1900:

Mullingar dry dock ~1900

The photo below was taken into the sun, alas. The entrance to the dry dock is towards the top of the entrance. So why are there curved stones closer to the camera? Was there once a second dry dock? Or was a second dock planned without ever beinf constructed? Or was the dock moved from one site to the other?

Entrances?

 

The Ruth Delany and Peter Clarke histories say nothing about this. If you can shed light on the matter, please leave a Comment below.

Great Island and Tarbert

The waterway power stations are back in the news again.