John Speller's Web Pages Portland Breakwater Railway

John Speller's Web Pages - Other Railways
Portland Breakwater Railway Untitled Untitled
The Portland Breakwater, constructed by the Admiralty in 1847-62 created what was then the largest artificial harbor in the world. The works involved an extensive 7 ft. gauge railway system. Charles Dickens gave a description in Household Words, 17 April 1858:

"We walk forward at once towards the huge staging. The pathway is lined with blocks of stone, iron rails, and timbers; here and there lies a broken pile, with the shoe and Mitchell's screw attached. […] Up the hill to the right run the inclines ; the heavy four-wagon trains rattle down them and flit by us, each with “Prince Albert” or “Prince Alfred” puffing away behind, and dashing them off rapidly to the far end of the cage. A mile of this fine stagework is complete, and one cannot do better than start off and walk the mile. A good railed passage is provided, leading between two of the five broad-gauge roads which run to the end of the inner breakwater abreast over open rafters. The large blocks of heaped stone, which at first underlie the rafters, soon become dashed with surf, and then give way entirely to the sea, which, if the day be at all fresh, will give the visitor a sprinkling. Six hundred yards from the shore the inner breakwater ends in a noble bastion-like head, rising, with smooth round sides, some thirty feet above the waves. A space of four hundred feet separates this head from its partner, the precisely similar work at the end of the outer breakwater. The staging at this point is carried out a little to the right (not passing over the heads, but swerving slightly from them) and is narrowed to three lines of road instead of five; but, upon reaching the outer limb of the work, the five lines immediately re-assemble, and go on. together all the rest of the way. This intervening piece of three-line staging is the perfect part of the whole cage. Its firm unyielding timbers will bear, almost without vibration, the forty-eight tons of the four loaded wagons, and the weight of the engine, too. The case is far different as they pass over the older timbers near the shore, which are also unsupported by the iron rods found further on, and over which the trains dance up and down as they pass, and seem to hover about the extremest limit of safe passage.

"From the point where the five lines reassemble, the whole course is free from interruption to the further end. It is a scene of bustle. Here, we pass a gang of men preparing timber for the shores and brackets that support the road-pieces; there, we see a man running along the narrow footway of the workmen—a single plank laid on each side of the rails—as much at ease as if a false step would not tumble him thirty feet down into the sea, or, worse, upon the rugged rubbly heap; which, now emerging from the waves, indicates what the nature of this outer arm is hereafter to be. The inner breakwater is already being cased with dressed stone; but the outer portion is to be left—at least, according to the present estimate—as a rough slope of rubble, which will keep the sea out quite as well. Every two or three minutes comes rumbling behind us a train, with its four loaded wagons, each wagon averaging twelve tons in weight. An ordinary load consists of a large block in the centre, some two or three feet in diameter, around which are heaped fragments of smaller sizes, the whole rising to a considerable height in the wagon. It is a fine thing to watch the tipping of the rubble through the open rafters of the cage. Every wagon has a dropping-floor, slanting downwards from back to front, but with its iron-work lighter and less massive in front than behind. It is so contrived that a brakesman, with a few blows of his hammer, knocks away the check, and sets the floor free to drop; the front drops at once, because, owing to its greater depth, it is pressed by the greater weight of stone; the whole mass tumbles with a confused uproar upon the rubble-heap below, and then the heavy iron-work behind causes the floor at once to return to its natural position, in which it is immediately re-fastened. A puff or two of the engine brings each wagon in succession over the required spot; and, unless the large stone should become jammed, the whole load is tipped, and the empty train is on its way back, in less than a minute. The jamming, when it happens, is an awkward business, and men are sometimes at work for hours with picks and crowbars before some obstinate mass will slip between the iron sides. Such accidents are almost always the result of careless packing on the part of the convicts at the top of the inclines: the process being, indeed, one that demands not a little art and skill. When the rubble embankment was still below the surface, the effect of the tipping was greatly heightened by the fine hollow roar of the great plunge into the water, and by the column of spray that was dashed high into the air.[…]

"As we return along the cage, we stop to watch the “travellers" at work, where masons are setting the coping-stones of casing for the inner breakwater. Two small-wheeled trucks, perhaps eight feet apart, stand on a line of rails. On a parallel line, sixty feet distant, there are two similar trucks. From all four trucks uprights rise to the height of twelve or fourteen feet, and across these uprights a platform is laid. There are four winches, one outside each upright, by which four men can move the whole machine up or down the two widely parted lines of rails which may have two or even more lines lying between them. This extensive apparatus is required for the support of a crane, but not a common crane. It has a crane that has not great arm reaching up into the air, but consists of a series of compact, well-adjusted wheels on a small stand, which can be run upon rails up and down the sixty feet of platform. Some of the travellers are made still more complete by pivots at the top of each upright, which allow one end of the platform to be wheeled a given distance along its own set of rails, without compelling any movement at the other end. This is the machine used for setting the stone of the breakwater casing. The crane will hold a block of several tons weight neatly hewn for the cornice which is crowning the six courses of granite wall below, and grip it fast while the workmen adjust and re-adjust, enabled by this means to set with all the nicety that could be used in the adjustment of a stone weighing pounds instead of tons. A spirit-level is invariably used; and it was also employed five-and-twenty feet below the surface of the water, by the diving masons, who, in Deane's diving dress, adjusted the foundations of the splendidly built heads. Some notion may be formed of the work bestowed upon the heads, by the fact that, though four hundred feet asunder, six inches is the utmost difference between their levels. Three hundred pounds is the lowest cost of one of the large travellers.

"To know what the cage is like, we should observe the work of pushing out a new bay, or tier, or row of piles, from the end of the staging. The piles, which are made in the yard, are formed of double timbers, the two beams being securely bolted and tree-nailed together. The pieces are scarfed: that is, cut so as to overlap and be joined even or flush, and the whole pile is in section fourteen inches by twenty-eight. As soon as it is made, each pile is thrust into an airtight cylinder, and, the air both from the cylinder and the pores of the wood being extracted by means of an exhaust pump, creosote is introduced instead of air. A considerable pressure is put on, until the wood has absorbed the right number of pounds of creosote to the hundredweight. Trussed booms of at least sixty feet in length (huge rafters with perpendicular pieces fixed beneath), are now rigged out from the present staging, one boom from the centre of each road, making five in all. Each boom projects thirty feet overboard, that being the distance at which the next bay of piles is to be constructed. They are kept from swaying out of the proper direction by long pieces of timber, some six inches square, fixed to their outer end and to a point on the present staging.

"The booms being thus provided for, the piles are next towed out, with cast-iron weights attached to the ends, in addition to the shoe and the Mitchell's screw, with which they are to be screwed eight feet into the ground. The ends, in consequence, sink; and the heads are hoisted up into the jaw, or forked opening formed in the outer ends of the booms. Thus the piles are held in position over the spot of ground to which they must be screwed. Capstan heads are on the heads of the piles, into which capstan bars are now put, having on the end of each a small jaw or bird's-niouth, to bite the rope when inserted. Wheeled-platforms, called trollies, are then run up to the head of the staging, and fixed there. Each trolly has a crab mounted, and firmly bolted upon it; that is, a set of winding machinery, with a barrel, and winch, and spur-gear, increasing the power and communicating motion from the winch to the barrel. Men are stationed at the crab, and as soon as they commence winding, motion is given to the capstan-bars, and by them to the pile, which is thus firmly screwed into the ground. Crossheads, of double timbers like the piles, are now fitted into their upper ends, which are formed so as to receive them, and the whole is securely bolted through. Long cranes of thirty-feet gauge are used to drop these crossheads into place. Tie-rods are also put through the piles just above the level of low water mark, to give them a greater degree of firmness, Trussed road-pieces made in the yard can now be fitted athwart the crossheads, one on either side of each pile ; other timbers, called transoms and chocks, for securing the roadway in its true position, are fitted in, and the narrow plank for the workman's footway is attached to either side, and supported by brackets. The cost of making and fitting every single pile is about seventy pounds; and not less than twelve or thirteen hundred constitute the staging as it now exists. The general width of the breakwater staging where five roadways run is one hundred and fifty feet; and the length of the piles at the outer end ninety feet, exclusive of shoe and screw, thus allowing, in ten fathom water, thirty feet clear above the level of low water of ordinary, spring tides. We have seen that the staging between the two heads, where three roads only run, is steadier and less yielding to the weight of the wagons than that on either side of it, but especially near the shore. This arises from the outside pile only being trussed and stayed in the bay or row of five piles, whereas in the rows of three all the piles are supported thus; each pile is further strengthened by screw moorings, that is, by long rods of iron reaching from the head of the timbers, and screwed into the ground at a considerable angle."
Contemporary print showing the method of construction of the Portland Breakwater
Broad gauge 0-4-0T "Queen" built by E. B. Wilson & Co. for the Portland Breakwater Railway in 1853, in use at Portland before it went to the Torbay & Brixham Railway in 1870. It once fell into the sea — hence the awkward chimney repair
Map of the Portland Breakwater and Railways. On completion of the works the broad gauge lines were replaced b a conventional 4 ft. 8½ in. harbor railway
Brunel's SS "Great Eastern" leaving Portland Harbour with the newly-completed breakwater behind it
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