In the preceding Sections the manner of laying down plans has been fully
described and the principles involved in the operations minutely
explained. It now only remains, therefore, to direct attention to
certain matters relating to the preparation of plans, which are
necessitated by the circumstances of particular cases.
Civil engineers’ plans usually consist, if we except harbour surveys, of
a representation, to a rather large scale, of long and narrow tracts of
country through which it is proposed to construct a means of
communication, such as a railway, a road, or a canal. They do not differ
essentially from other plans, the survey being taken in the ordinary
way, and the plan laid down according to one or other of the methods
described in the preceding Section. The width of railway surveys varies
from five to twenty chains, at the option of the engineer. An important
matter demanding careful attention is to survey, plot, and number all
fields and other enclosures, houses and other buildings situate within
the _limits of deviation_, that is, the boundaries of the space beyond
which it is not proposed to deviate the line of railway. The object of
numbering every separate enclosure, road, building, or other object on
the plan, is that they may be the more readily described in a book
prepared for that purpose and called the Reference Book. Parish and
county boundaries are shown by dotted lines, as explained in a former
Section. Frequently it is necessary, in consequence of the smallness of
the scale adopted for the plan, to give enlarged drawings of certain
portions. In these cases, whenever practicable, the enlarged plan should
be placed directly under or over the small plan to which it refers, as
such an arrangement is not only more pleasing to the eye, but is far
more convenient for reference than one in which there is no relation of
position between the two plans. The proposed railway should be
represented by a full and heavy line, and the limits of deviation shown
by strong dotted lines. The names of the different parishes through
which the line passes should be conspicuously written, and the name of
the county placed at the top of each sheet; the sheets also should be
distinctly numbered. It is not usual to distinguish different kinds of
fences on plans of engineering projects, as on estate plans to a large
scale; on the former it is sufficient to distinguish between fenced and
unfenced lines of division of land, marking the former by plain, and the
latter by dotted lines. It is almost needless to remark that a scale of
distances should accompany every plan.
The section should be drawn to the same horizontal scale as the plan,
and the exaggeration of the vertical scale should be such as to show
distinctly the irregularities of the surface. The horizontal datum line
of the section should have marked on it a scale of distances
corresponding with those marked along the centre line of the plan, in
order that corresponding points on the plan and the section may be
readily found, and great care should be taken that horizontal distances
on the plan and on the section exactly agree. Cross sections are
longitudinal sections of existing lines of communication which the
proposed work will cross; they may cross the centre line of the proposed
work either at right angles or obliquely. Cross sections may also be
required where the ground slopes sideways; in general they should be
ranged accurately at right angles to the centre line, and they should be
plotted without exaggeration, that is, their vertical and horizontal
scales should be the same as the vertical scale of the longitudinal
section. All cross sections should be plotted as seen by looking
_forward_ towards them along the centre line.
To distinguish the nature of the soils passed through, sections are
frequently coloured, as shown in Plate 21. The information given by this
means concerning the character of the strata is of very great value to
the engineer or to the contractor, inasmuch as it enables them to
predicate with some degree of certainty the amount of labour that will
be required in executing the proposed work. It is, therefore, highly
important that the draughtsman correctly represent the character of the
strata. The conventional modes of representing these features are shown
on Plate 20, which should be carefully studied and copied.
It is necessary that the engineering draughtsman should be acquainted
with the “Standing Orders” of Parliament relating to the preparation of
plans and sections, in order that he may fulfil the conditions therein
laid down. And as most of the important details involved by the
exigencies of practice in the preparation of such plans and sections are
prescribed by these Standing Orders, we will give so much of them as
relates directly to the matters under consideration; by so doing, the
details will be clearly and fully described, and the requirements of the
law concerning them authoritatively made known.
_Nature of the Documents required._--“In cases of bills relating to
engineering works, a plan and also a duplicate thereof, together with a
book of reference thereto, and a section and also a duplicate thereof,
as hereinafter described, shall be deposited for public inspection at
the office of the clerk of the peace for every county, riding or
division in _England_ or _Ireland_, or in the office of the principal
sheriff clerk of every county in _Scotland_, and where any county in
_Scotland_ is divided into districts or divisions, then also in the
office of the principal sheriff clerk in or for each district or
division in or through which the work is proposed to be made,
maintained, varied, extended or enlarged, or in which such lands or
houses are situate, on or before the 30th day of _November_ immediately
preceding the application for the bill.”
“In the case of railway bills, the ordnance map, on the scale of one
inch to a mile, or where there is no ordnance map, a published map, to a
scale of not less than half an inch to a mile, or in Ireland, to a scale
of not less than a quarter of an inch to a mile, with the line of
railway delineated thereon, so as to show its general course and
direction, shall, on or before the 30th day of _November_, be deposited
at the office of the clerk of the peace, or sheriff clerk, together with
the plans, sections, and book of reference.”
“In cases where the work shall be situate on tidal lands within the
ordinary spring tides, a copy of the plans and sections shall, on or
before the 30th day of _November_, be deposited at the office of the
Harbour Department, Board of Trade, marked ‘Tidal Waters,’ and on such
copy all tidal waters shall be coloured blue, and if the plans include
any bridge across tidal waters the dimensions as regards span and
headway of the nearest bridge, if any, above and below the proposed new
bridge, shall be marked thereon, and in all such cases such plans and
sections shall be accompanied by a published map or ordnance sheet of
the country, over which the works are proposed to extend, or are to be
carried, with their position and extent, or route accurately laid down
thereon.”
“In the case of railway bills, a copy of all plans, sections, and books
of reference, and the aforementioned published map with the line of
railway delineated thereon so as to show its general course and
direction, is required to be deposited at the office of the Board of
Trade, and at the Private Bill Office of the Houses of Parliament; and
in cases where any portion of the work is situate within the limits of
the Metropolis, a copy of so much of the plans and sections as relates
to such portion of the work is required to be deposited at the office of
the Metropolitan Board of Works. Also a copy of so much of the plans and
sections as relates to each parish in or through which the work is
intended to be made, or in which any lands or houses intended to be
taken are situate, together with a copy of so much of the book of
reference as relates to such parish, is required to be deposited with
the parish clerk of each such parish in _England_, with the
school-master of each such parish in _Scotland_, and with the clerk of
the union within which such parish is included in _Ireland_.”
_Plans._--“Every plan required to be deposited shall be drawn to a scale
of not less than four inches to a mile, and shall describe the line or
situation of the whole of the work (no alternative line or work being in
any case permitted), and the lands in or through which it is to be made,
maintained, varied, extended or enlarged, or through which every
communication to or from the work shall be made; and where it is the
intention of the parties to apply for powers to make any lateral
deviation from the line of the proposed work, the limits of such
deviation shall be defined upon the plan, and all lands included within
such limits shall be marked thereon; and unless the whole of such plan
shall be upon a scale of not less than a quarter of an inch to every one
hundred feet, an enlarged plan shall be added of any buildings, yard,
courtyard or land within the curtilage of any building, or of any ground
cultivated as a garden, either in the line of the proposed work or
included within the limits of the said deviation, upon a scale of not
less than a quarter of an inch to every one hundred feet.”
“In all cases where it is proposed to make, vary, extend or enlarge any
cut, canal, reservoir, aqueduct or navigation, the plan shall describe
the brooks and streams to be directly diverted into such intended cut,
canal, reservoir, aqueduct or navigation, or into any variation,
extension or enlargement thereof respectively, for supplying the same
with water.”
“In all cases where it is proposed to make, vary, extend or enlarge any
railway, the plan shall exhibit thereon the distances in miles and
furlongs from one of the termini; and a memorandum of the radius of
every curve not exceeding one mile in length shall be noted on the plan
in furlongs and chains; and where tunnelling as a substitute for open
cutting is intended, such tunnelling shall be marked by a dotted line on
the plan.”
“If it is intended to divert, widen or narrow any turnpike road, public
carriage road, navigable river, canal or railway, the course of such
diversion, and the extent of such widening or narrowing shall be marked
upon the plan.”
“When a railway is intended to form a junction with an existing or
authorized line of railway, the course of such existing or authorized
line of railway shall be shown on the deposited plan for a distance of
eight hundred yards on either side of the proposed junction, on a scale
of not less than four inches to a mile.”
_Book of Reference._--“The book of reference to every such plan shall
contain the names of the owners or reputed owners, lessees or reputed
lessees, and occupiers of all lands and houses in the line of the
proposed work, or within the limits of deviation as defined upon the
plan, and shall describe such lands and houses respectively.”
_Sections._--“The section shall be drawn to the same horizontal scale as
the plan, and to a vertical scale of not less than one inch to every one
hundred feet, and shall show the surface of the ground marked on the
plan, the intended level of the proposed work, the height of every
embankment and the depth of every cutting, and a datum horizontal line,
which shall be the same throughout the whole length of the work, or any
branch thereof respectively, and shall be referred to some fixed point
(stated in writing on the section), near some portion of such work, and
in the case of a canal, cut, navigation, turnpike or other carriage road
or railway, near either of the termini.”
“In cases of bills for improving the navigation of any river, there
shall be a section which shall specify the levels of both banks of such
river; and where any alteration is intended to be made therein, it shall
describe the same by feet and inches, or decimal parts of a foot.”
“In every section of a railway, the line of the railway marked thereon
shall correspond with the upper surface of the rails.”
“Distances on the datum line shall be marked in miles and furlongs, to
correspond with those on the plan; a vertical measure from the datum
line to the line of the railway shall be marked in feet and inches, or
decimal parts of a foot, at each change of the gradient or inclination;
and the proportion or rate of inclination between each such change shall
also be marked.”
“Wherever the line of the railway is intended to cross any turnpike
road, public carriage road, navigable river, canal or railway, the
height of the railway over or depth under the surface thereof, and the
height and span of every arch of all bridges and viaducts by which the
railway will be carried over the same, shall be marked in figures at
every crossing thereof; and where the roadway will be carried across any
such turnpike road, public carriage road or railway, on the level
thereof, such crossing shall be so described on the section; and it
shall also be stated if such level will be unaltered.”
“If any alterations be intended in the water level of any canal, or in
the level or rate of inclination of any turnpike road, public carriage
road or railway, which will be crossed by the line of railway, then the
same shall be stated on the said section, and each alteration shall be
numbered; and cross sections in reference to the said numbers, on a
horizontal scale of not less than one inch to every three hundred and
thirty feet, and on a vertical scale of not less than one inch to every
forty feet, shall be added, which shall show the present surface of such
canal, road or railway, and the intended surface thereof when altered;
and the greatest of the present and intended rates of inclination of
such road or railway shall also be marked in figures thereon; and where
any public carriage road is crossed on the level, a cross section of
such road shall also be added; and all such cross sections shall extend
for two hundred yards on each side of the centre line of the railway.”
“Wherever the extreme height of any embankment, or the extreme depth of
any cutting, shall exceed five feet, the extreme height over or depth
under the surface of the ground shall be marked in figures upon the
section; and if any bridge or viaduct of more than three arches shall
intervene in any embankment, or if any tunnel shall intervene in any
cutting, the extreme height or depth shall be marked in figures on each
of the parts into which such embankment or cutting shall be divided by
such bridge, viaduct or tunnel.”
“Where tunnelling, as a substitute for open cutting, or a viaduct as a
substitute for solid embankment, is intended, the same shall be marked
on the section.”
“When a railway is intended to form a junction with an existing or
authorized line of railway, the gradient of such existing or authorized
line of railway shall be shown on the deposited section, and in
connection therewith, and on the same scale as the general section, for
a distance of eight hundred yards on either side of the point of
junction.”
Besides the information thus written on the plan, it is useful to the
engineer, though not prescribed, to have the levels of important points
either written or shown by means of contour lines, especially when the
plan is to be used in selecting a line of railway. The results of trial
pits and borings may also be written on the plan, and the estimated cost
of each part of the work placed opposite to its position on the paper.
_Working Sections._--For working sections the horizontal scale adopted
is usually three or four chains to the inch, and the vertical scale 30
or 40 feet to the inch. A working section should show the level of the
ground, the level of the proposed work, and the height of embankment or
depth of cutting at every point of the ground where the level has been
taken, these quantities being found by calculation, not by measurement
on the paper. The position and levels of all “bench marks” should also
be clearly indicated. At every crossing of road, river or stream of any
kind, should be inserted some remark respecting the work to be
constructed, with a reference to the number of the working drawing
prepared. The latter may be a special drawing, as for a bridge, or a
general drawing, as for a level crossing and gates. The results of
boring should also be shown on the working section. As soon as the works
of construction have been determined upon, notes should be inserted from
the working drawings, or other sources, of the angles of skew at which
the line crosses roads or streams, the spans of arches on the square and
on the skew, the rise of the arch, the depth of the arch stones, and of
the puddle, if any be used, and, if the works be on an inclined plane,
the rise or fall from centre to centre of the piers. Similar memoranda
should also be made of girder bridges, culverts, and other works
occurring along the line. To all working drawings the acting engineer
always affixes his signature.
Besides an acquaintance with the “Standing Orders,” the engineering and
surveyor’s draughtsman should possess a knowledge of the Regulations of
the Local Government Board, for these have to be complied with in the
preparation of plans relative to main sewerage, drainage, and
water-supply. These Regulations are as follows.
_Boundary Maps._--In cases in which a special district is proposed to be
formed for the adoption of the Local Government Act, a map must be
submitted, accompanied by a written description of the proposed
boundary, designated by letters from point to point, commencing from a
fully and clearly defined point on the north side of the map marked by
the letter A and a written description, then proceeding eastward by
natural or other well-defined features, until the description closes
upon the point started from. The name of the proposed district must be
printed on the map, with the area in acres. The population and the
number of houses, with the rate of increase as ascertained at the two
last decennial periods upon which the census was taken, must be given,
and a duplicate or tracing of the map furnished.
_Maps for Division into Wards._--A map of the entire district must, in
this case, be submitted, with the main boundary distinctly defined, and
the name of the district clearly printed thereon. The proposed division
into wards must be by lines, clearly defined on the map of the district;
brooks, roads, footwalks, streets, fences, or other easily recognizable
lines of division may be adopted. Such lines must be defined on the map
by a margin of colour. The proposed boundary-lines must be described in
the same manner as in the boundary map, and the name or number of the
ward, with the relative areas, population, and rateable value must be
given. A duplicate map or a tracing must be deposited at the Local
Government Act Office for future reference.
_Plans of Proposed Works._--It is in all cases necessary, upon
application being made by Local Boards for the Secretary of State’s
sanction to a loan for the execution of works, that plans, sections,
detailed estimates, and specifications be submitted with the
application, accompanied with the information relative to area,
population, number of houses, and rateable value of the district
required for boundary maps. Tracings of such plans and sections, and
copies of the estimates and specifications must be sent in for filing at
the Local Government Act Office.
_General Plan._--A general plan exhibiting the area which will be
affected by the proposed works must be laid down to a scale of not less
than _two feet to a mile_. It should have figured upon it the levels of
the centres of all the streets and roads at their intersections and
angles, and at every change of inclination; also, where a district is
near the sea, it should show the high and the low tide level of the sea,
and where there is a river, the summer and the flood-water levels should
be recorded. Permanent bench marks having reference to the surface
levels should be cut on public buildings, or other permanent and
suitable objects, throughout the district, and clearly marked on the
plan. Sections should accompany this plan, upon which the levels of the
cellars should be shown. Such a plan may be used for showing the lines
of main-sewers and drains, lines of water-pipes, and gas-mains. The
lines of main-sewers and drains should have the cross-sectional
dimensions and the gradients distinctly marked upon them. The
dimensions of water and gas pipes should also be shown in figures or in
writing.
_Detailed Plan._--A detailed plan for the purposes of house-drainage,
paving, the sale and purchase of property, or other purposes of a like
character, must be constructed to a scale of not less than _ten feet to
a mile_. Upon this plan must be exhibited all houses and other
buildings, bench marks, the levels of streets and roads, of cellars, of
the sea at high and low tide level, and the summer and the flood level
of rivers. Three feet by two feet will be a convenient size for the
sheets of this plan, and by representing the marginal lines of the
sheets upon the general plan, and numbering the sheets to correspond,
the general plan will become a very useful index.
As it may occasionally be desired to carry out works piecemeal, with a
view to save the time which would be occupied in the preparation of a
complete plan from actual survey, it is sufficient in the first instance
to furnish a general plan of streets and roads only, with the surface
levels and those of the deepest cellars, and the proposed scheme of
works shown thereon, after which the works can proceed in sections. But
with each separate application for sanction to a loan, a correct plan
and section or sections should be submitted, accompanied by detailed
estimates and specifications. It must, however, be understood that the
complete plan of the entire district must be proceeded with, so that,
when the works are finished, the Local Board and the office of the Local
Government Act may possess a proper record.
_Mining Plans._--The plotting of mining surveys is performed in the same
manner as the surface traverse surveys already described. Before
proceeding to lay down the plan, it is well to divide the paper into
squares of 10 chains side, or 10 acres area, by two sets of lines
crossing each other at right angles, one of which sets should represent
meridians. This operation should be performed with scrupulous care; and
to ensure accuracy, beam compasses should be used to lay off the
divisions. The lines should be finely drawn in colour to distinguish
them from other lines to be put upon the drawing. Care must be taken to
get the plan fairly upon the paper, so that the conformation of the
outline or boundary to the edges of the paper may have a pleasing effect
to the eye; and the direction of the meridians must be determined
according to this condition. By having the plan thus divided into
squares of 10 acres each, the quantity of ground worked out may be
approximatively estimated at any time by inspection, and the total
quantity may be readily computed in the same manner. Besides dividing
the plan itself in this way, it will be found extremely useful to have a
sheet of tracing paper, or better, tracing cloth, divided into squares
of 316·228 links side, or 1 acre area, in black lines; each of such
squares being subdivided into 4 by lines in colour, to show quarters of
an acre. To find the area of any portion of exhausted or of unworked
ground, it is only necessary to lay this divided sheet over such portion
and to count the squares and quarters included in it.
By reason of the variations of the magnetic meridian, the date of a
survey should always be written on the plan; and as the plan of
underground workings is laid down piecemeal as the workings progress,
often extending over a period of many years, care must be taken to
reduce all bearings to the original meridian. Unless these matters are
strictly observed, serious errors may result.
When two or more veins of mineral are being worked one above the other,
and are placed upon the same plan, they are distinguished by means of
colour. It matters not what colours are employed for the several
separate workings so long as they are distinct from each other. Also the
mode of applying the colour, whether with the brush or with the pen, is
entirely a question of taste. It may, however, be observed that as
mining plans are constantly being added to, it is very difficult to
avoid a patchy appearance when the colour is laid on with the brush.
Plate 33 shows the manner in which mining plans are got up.
_Estate and Town Plans._--Plans of estates and towns, including as they
do only a limited area and requiring great distinctness of detail, are
laid down to a large scale; for the form and character of the detail
are, on such plans, of equal importance with its position. With such a
scale as is required in these cases, it is possible, not only to clearly
distinguish natural and artificial features, but to introduce means of
producing pictorial effect into their representation. The nature of
these means may be seen in the examples of plans appended to this work.
The manner of showing the various kinds of fences has been already
described. Trees are usually shown in elevation for the sake of artistic
effect; but care must be taken to give them such dimensions as will
accord with the scale of the drawing. Houses and other buildings are
shown in plan of the correct form, and washed for distinction in light
red for dwelling-houses, dark grey for outhouses, and light grey for
public buildings. Dark grey is also used for all wooden and iron
buildings to distinguish them from those constructed of the ordinary
materials, brick and stone. But besides such distinctions, others are
needed to indicate the character of natural features and artificial
constructions. These are obtained either by showing the object roughly
in elevation, or by some purely conventional means. The signs of this
character that are likely to be frequently required on estate plans are
shown on Plate 15. The manner of representing water, which has been
described in a preceding Section, will be found illustrated in detail on
Plate 11. Plates 10 and 14 show various kinds of trees; in this form
they may be introduced very effectively into plans of estates.
The several stages which a plan passes through in the office are shown
on Plate 2. If the plan is to be coloured, the colouring must be done
before the lettering is put on. Plate 3 shows a plan lightly coloured,
as used by surveyors, solicitors, and others; and Plate 17 shows a
finished plan in colour. The methods of laying on the colours and the
principles involved in the operations have been fully described and
explained in a former Section. In Plate 13 is given a town plan showing
a proposed street improvement. Such a plan must be laid down to a large
scale, and the details in and near the part affected must be drawn in
clearly and accurately. The uncoloured portion represents the plan as
prepared for lithographing. When pink colour is used to show the
proposed street, the buildings should be coloured in black by a light
wash of Indian ink. Yellow or any other bright tint may be used for the
proposed street, the object being merely to distinguish it clearly.
Existing streets should be coloured in yellow ochre, except when that
colour is used for the proposed street, in which case burnt sienna may
be used.
The Plates relating to this Section are Nos. 2, 3, 10, 11, 13, 14, 15,
17, 19, 20, 21, and 33.