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the nearest fence or other object shown on the map. remarked, it will facilitate the levelling if the chainage of each fence crossed by the line is pencilled in figures on the map, as the leveller can then work to these chainages. The leveller should also be provided with a scale to scale distances or intermediate chainages on the map.
Owing to the limited time usually available for Parliamentary surveys, and as the location is by no means a final one, while the limits of deviation as a rule leave ample room for alteration in the final location, the location above described is usually all that can be done on a Parliamentary survey. The method of making a proper final location will be found described on pages 225, 226, 227.
Correcting the 6 in. Ordnance. The limits of lateral deviation prescribed by the Parliamentary Regulations are 300 ft. on each side of the centre line of the railway in the country, and 30 ft. in towns. They are the limits within which the centre line of the railway may be altered when the detailed or working survey is made after Parliamentary sanction has been given to the scheme. The limits of vertical deviation are 5 ft. in the country and 2 ft. in towns. As the Parliamentary plans must show all details correctly within the limits of deviation, it is necessary to pencil on the limits of deviation as well as the centre line, so that any corrections necessary may be made. As the date of the Ordnance Survey map may be a considerable number of years prior to the date of the railway survey in hand, in some cases a good deal of labour is necessary to correct alterations to existing features, such as fences, &c., survey and plot on new buildings, &c. When there is not much alteration the leveller may be able to correct the Ordnance within the limits of deviation while taking the levels, but as a rule it is more expedient for him to devote certain days to this. If there is much alteration, and the time is limited, it will be necessary to have a special assistant to correct the Ordnance. All buildings included within the proposed limits of deviation must be surveyed and plotted to a scale of not less than 400 ft. to 1 in. They are usually plotted on the 25 in. Ordnance sheets if not already shown on these. These sheets should therefore be obtained for those parts of the line where buildings are to be included, and handed to the assistant whose duty it is to correct the map within the limits of deviation.
Referencing. Every field, enclosure, building, road or path within the limits of deviation must be numbered on the plan and the numbers entered in a book of reference, together with owner or reputed owner, lessee or reputed lessee, and description, i.e., whether arable, pasture, &c. All parish and county boundaries are also to be shown on the plan, as well as the names of all the parishes and counties through which the railway passes. The work of referencing is done by the solicitors to the promoters of the scheme, to whom should be supplied a set of 6 in. Ordnance sheets corrected to date and with the limits of deviation and the centre line of the railway marked on. It will as a rule be necessary for the engineer to send an assistant out with the solicitor's clerk to number and identify fields, enclosures, buildings, &c., on the map.
Preparation of Parliamentary Plans.-The Parliamentary plans are usually prepared by tracing from the 6 in. Ordnance on which the line has been laid down. They are made of a uniform size in sheets each containing 4 miles of the railway. The section of the part on each sheet is shown underneath the plan. Where it is intended to include within the limits of deviation any building, yard, courtyard, or land within the curtilage of any building, or any ground cultivated as a garden, an enlargement of this must be shown to a scale of not less than 400 ft. to 1 in. These enlargements, as already stated, are usually taken from the 25 in. Ordnance sheets. The limits of deviation are shown on the plan by a dotted line. Any enlargements are drawn under or above the general plan at the points where the buildings, &c., to which they refer are situated.
The tracings are handed to one of the lithographic firms which make a specialty of this class of work, and they are retraced by their draughtsman in specially prepared lithographic ink, and the figures and writing neatly printed on in the usual conventional styles of printing. As Parliamentary surveys are often only decided on at the last minute of available time, the engineer and surveyor have not as a rule time to spend in elaborate printing and figuring, &c. The description and figuring on the tracings are therefore simply written on in ordinary plain handwriting, to be copied by the lithographic draughtsman in neat printing. The lithographic tracing having been impressed on the stone, proof sheets are sent for correction, and the corrected lithographs are then prepared and
bound up in proper order. The engineer retains some copies for his own use and sends the remainder to the solicitors for the proposed railway, who deposit copies with the various local authorities &c., as specified in the statutory regulations.
Preparation of Parliamentary Sections. The section is plotted in the usual manner, the gradients and gradient lines representing the surface of the rails being shown on it, to the same horizontal scale as the plan, and to a vertical scale of 100 ft. to I in., which conforms to the Standing Orders. The section must be referred to a known datum which is usually one of the Ordnance bench marks near one end of the line. The rail level at each change of gradient must be figured on, together with the distances in miles and furlongs, point of commencement and termination of each railway and branch, with total length of each in miles, furlongs, and chains. All public roads, railways, and canals which are crossed, how crossed, i.e., whether by a level crossing or by a bridge, whether to be raised or lowered, and if so, how much, and the span and headway of each bridge, are also to be marked on the section. The extreme height of any embankment or depth of any cutting, where these exceed 5 ft., must also be figured on. Public roads crossed by level crossings must be levelled along for 200 yds. on each side of the point of crossing, and a section shown to an enlarged scale of not less than 5 chains to I in. horizontal and 40 ft. to 1 in. vertical. When many roads are thus crossed, they add very considerably to the leveller's work. Every public road the level of which is to be altered must have a cross section drawn to the same scales, and the greatest present and intended rates of inclination marked thereon in figures.
As already stated, the section of each 4 miles is shown on the same sheet as the general plan of that part of the line and underneath it. The sections of roads crossed are shown on a separate sheet or sheets placed at the end of the general plan and section. They are, however, sometimes placed above the general longitudinal section at the points where they occur.
Another point to be noted is that when a junction is intended with any existing or authorised railway, a plan and section of the existing railway must be shown for 800 yds. on each side of the point of junction, to the same scales as the general plan and section.
Parliamentary Estimate.-An estimate of the probable cost of the proposed railway has to be made out in a form prescribed by the Board of Trade. This estimate must state the quantities and cost of the various items; cuttings, embankments, bridges, accommodation works, viaducts, culverts and drains, metalling of roads, permanent way and fencing, sidings, junctions, stations, contingencies, land and buildings, &c.
Board of Trade Regulations for Light Railways.— Of late years, in order to avoid the expensive procedure necessary to get a Bill passed by Parliament authorising the construction of a railway, the Light Railways Act has been passed, and the Board of Trade in September 1896 issued their "Rules with respect to applications to the Light Railway Commissioners for orders authorising Light Railways." The engineer should provide himself with a copy of the latest rules, which may be had on application.
Under the Light Railways Act it is not necessary to go to Parliament for sanction to construct a railway if it is made to come under the regulations of the Light Railways Act which chiefly affect the signalling and working of the line. The scheme is considered by the Light Railway Commissioners, at an inquiry held locally, at which the engineer must attend and give evidence. If sanctioned by them, it is then passed on to the Board of Trade for final approval. As far as the engineer or surveyor is concerned, his work is much the same whether the line is an ordinary railway or a light railway.*
Example of Parliamentary Plan and Section of Railway taken from actual practice. Figs. 167, 168, Plate VIII., are examples of the Parliamentary plan and section of a railway actually constructed and surveyed as already described in this chapter.
Working Surveys.-The Bill having been passed, or the sanction of the Light Railway Commissioners and Board of Trade having been obtained, the engineer is forthwith (let us hope) instructed by the promoters to proceed with the detailed or working survey.
of the Parliamentary Regulations for Ordinary Railways should be obtained, which may also be had on application.