Some Commonly used AutoCAD© Terms

Dimensions

Dimensions are used to convey size and specification in a drawing. When dimensioning a drawing, the final output scale of the drawing, the placement of dimensions, and how dimensions should appear should be taken care of.

The commonly used dimension styles are aligned, vertical and horizontal dimensioning. The below shown figure shows them all

Layers

As the Drawings becomes more and more complicated, organization of the drawing objects becomes complex too. To manage these objects layers can be used.

Layers can be defined as a set of transparent overlays as shown below

Using layers is similar to using overlays in a manual drafting environment where clear media that contain groups of related design elements are placed throughout the overall design. Each layer has property settings that determine the colour, line type, and line weight of the objects. The end result is that when all the layers are combined then it can be seen as one complete drawing, and has the flexibility to easily remove the overlays to focus only on certain aspects of the design. See the example below where the final drawing looks like the one shown below but actually it is achieved when objects in all the layers are seen together

The above is got when all the following layers are seen together

Here in this layer only the ground is drafted.

Here in this layer only the road profile is drafted.

Here in this layer only the dimensions are drafted.

Text Justification

One of the common types of text alignment in print media is justification. The various types of justification are shown below

• Left
• Centre
• Right
• Top Left
• Top Centre
• Top Right
• Bottom Left
• Bottom Centre
• Bottom Right

All the above mentioned justifications are shown below

Measure

Measure is an AutoCAD command using which objects can be placed in a curve or spline. To do this a block is needed with its base point being the point which is needed on the curve. After this the measure command can be invoked.

To understand this better consider the example where cross section lines are to be inserted at every 10m from the starting of the polyline which is the longitudinal line. The below mentioned steps are to be followed

• Step 1: Create a block named CS with the object being a line and the pick point being the middle of the line
• Step 2: Type the measure command and select the object as the polyline (longitudinal line).
• Step 3: Then type the Block option and type the block name as CS.
• Step 4: Then types yes for the Align block with object option.
• Step 5: Then type the length at which the block needs to be inserted.

Below shown is the figure before using block and after using block

Typical Irrigation Cross Section

In any irrigation project there are three types of cross section depending on which the sections are generated. The three cases are depending on whether the formation is just above ground, below the ground or is it very much above the ground. All the three cases can are as shown below

Case 1: When the formation is much above the ground. This is also called Banking section.

Case 2: When the formation is partially below ground. This is also called Partial Cutting section.

Case 3: When the formation is much below ground. This is also called Deep Cutting section.

The various portions of the cross sections in each of the above cases are shown below

Bed width: Below shown is the bed width of the canal

Full supply depth: This is the portion from the bottom of the canal to the water level inside the canal. Below shown is the full supply depth

Free board: Free board is the distance between the full supply depth and the top of the canal

Side slopes: Below shown is the canal side slope

Hearting: Hearting is the portion on the sides of the canal and is as shown below

Canal side slope of hearting: Below shown is the Canal side slope of hearting.

Outer side slope of hearting: Below shown is the outer side slope of hearting.

SR side top: This stands for Service Road and is shown below.

IP side top: This stands for Inspection Path and is shown below

SR side top width of hearting: Below shown is the SR side top width of hearting

IP side top width of hearting: Below shown is the IP side top width of hearting

Thickness of lining: Below shown is Thickness of lining.

Blanket: This is a layer below the CNS layer and is constructed in case of banking sections only and is shown below

CNS layer: It is the layer above the blanket and below the canal

Road thickness in cutting: Below shown is the Road thickness in cutting

Casing Thickness- inner side: This is the casing in-between the canal sides and the hearting side. Below shown is the Casing Thickness- inner side.

Casing Thick- outer side: This is the casing in-between the outer sides of hearting and the outer sides of the canal section. Below shown is the Casing thick outer side.

Berm: Berm comes only in a banking section and is shown below

Layer Organization in E Sections

The overall working of E Sections is on the layer concept i.e. all the data whether manually entered or auto-calculated is stored in different layers. These layers act like a set a transparent overlays which when seen together show the complete cross section or longitudinal section as designed. Some of the layers are used only for display purposes while most of them contain data. The properties of individual layers, like the linetype, the font used to represent data etc can be changed. There are altogether fifty layers. The description of each layer is mentioned below.

Layer Number	Used For	Functionality
Layer 1 to 6	Section Data	In this layer the sections data along with various settings is stored i.e. elevations or levels, remarks and layer numbers are stored. It is possible to enter cross section data upto 6 layers.
Layer 7 to 10	Display Purposes	These layers are used only for display purpose of the cross sections.
Layer 11	Profile	These layers contain the profile data i.e. the profile to be applied to the various cross sections
Layer 12 to 20	Multiple Profiles	These layers are used to apply multiple profiles
Layer 21 to 25	Insert Line	These layers are used to store information about the insert line option
Layer 26 to 30	Inclusive Layer	These layers are used to store information about the inclusive layer option
Layer 31 to 35	Gradient & Difference operation	These layers are used to store information about the Gradient and Difference option
Layer 36 to 38	Multiple Profiles	These layers are dummy layers and are used only for Multiple Profiles.
Layer 39 to 40	Area Calculation Layers	These layers are used to store and display information related to Area Calculation.
Layer 41 to 44	Blank Lines	Blank Lines
Layer 45 to 46	Reserved for Future purposes	These layers are dummy layers and are used only for customization and future improvement purpose.
Layer 47	Cutting Values	This layer is used to store the calculated Cutting values
Layer 48	Filling Values	This layer is used to store the calculated Filling values
Layer 49	Distance	This layer is used to store the distances
Layer 50	Cumulative Layers	This layer is used to store the auto calculated Cumulative distance

Nett Area Method of area calculation in E Sections

Consider the Cross section shown below

Cutting and Filling area needs to be calculated for the portion shown below

The first step towards the calculation involves calculating the distance and elevation at each intersection. Next step is to get both the Cutting area and the filling area, difference of the areas for both the layers is to be calculated at each distance. For example the Cutting area between the distances -7.5 to -6 is calculated by finding the areas for each layer and finding the difference between them. This is as shown below

This Cutting area (A1 – A2) is calculated using the formula

Cutting or Filling Area = ½(Distance 1 + Distance 2) * (Level at Distance 1 - Level at Distance 2)

Similarly area for the entire cross section can be calculated, which is as shown below

Cutting or Filling Area = A1 – A2

The detailed working using Nett area calculation is as shown below

Chainage	6000				Net Filling	7.72						Net Cutting	0.15
Initial Filling Area							Final Filling Area
Distance 1	Distance 2	Level 1	Level 2	Average	Distance	Area	Distance 1	Distance 2	Level 1	Level 2	Average	Distance	Area
-12	-10	77.21	77.21	77.21	2	154.42	-12	-10	77.34	77.34	77.34	2	154.69
-10	-9	77.21	77.34	77.28	1	77.28	-10	-9	77.34	77.34	77.34	1	77.34
-9	-7.5	77.34	77.81	77.58	1.5	116.36	-9	-6	77.34	78.84	78.09	3	234.28
-7.5	-6	77.81	78.36	78.09	1.5	117.13	-6	-5	78.84	78.87	78.86	1	78.86
-6	-4.5	78.36	78.65	78.51	1.5	117.76	-5	-3.5	78.87	78.91	78.89	1.5	118.34
-4.5	-2.25	78.65	78.64	78.65	2.25	176.96	-3.5	-0.2	78.91	79	78.95	3.3	260.55
-2.25	-1.6	78.64	78.67	78.66	0.65	51.13	0.93	3.5	78.98	78.91	78.94	2.57	202.89
-1.6	-1.5	78.67	78.68	78.68	0.1	7.87	3.5	5	78.91	78.87	78.89	1.5	118.34
-1.5	-0.75	78.68	78.71	78.69	0.75	59.02	5	6	78.87	78.84	78.86	1	78.86
-0.75	-0.2	78.71	79	78.85	0.55	43.37	6	7.46	78.84	78.11	78.48	1.46	114.89
0.93	1.1	78.98	78.76	78.87	0.17	13.41	7.46	12	78.11	78.11	78.11	4.54	354.32
1.1	1.5	78.76	78.76	78.76	0.4	31.51
1.5	2.25	78.76	78.74	78.75	0.75	59.06
2.25	3.8	78.74	78.8	78.77	1.55	122.09
3.8	3.85	78.8	78.65	78.73	0.05	3.94
3.85	4.5	78.65	78.67	78.66	0.65	51.13
4.5	6	78.67	78.64	78.66	1.5	117.98
6	7.46	78.64	78.11	78.38	1.46	114.75
7.46	7.5	78.11	78.1	78.11	0.04	2.81
7.5	9	78.1	77.13	77.62	1.5	116.43
9	10	77.13	76.9	77.02	1	77.02
10	12	76.9	77.31	77.11	2	154.22
					Total	1785.63						Total	1793.35
Initial Filling Area							Final Filling Area
Distance 1	Distance 2	Level 1	Level 2	Average	Distance	Area	Distance 1	Distance 2	Level 1	Level 2	Average	Distance	Area
-0.2	0	79	79.1	79.05	0.2	15.81	-0.2	0	79	79	79	0.2	15.8
0	0.75	79.1	79.2	79.15	0.75	59.36	0	0.93	79	78.98	78.99	0.93	73.46
0.75	0.93	79.2	78.98	79.09	0.18	14.24
					Total	89.41						Total	89.26

Profile

Profile is a concept used to define a template while construction of road, canal etc., which is applied to sections in order to meet the required design. This is a general requirement while road, canal design etc. The irrigation canal design or the road design is done depending on some standard shape/design. Even for widening or reconstruction of existing road, the same method of designing template is followed. Below shown are the typical profiles of road and canal

Simpson’s 1/3rd rule

Simpson’s 1/3rd rule is one of the most popular methods of finding the area under a given set of points, by the method of numerical integration. The basic idea is to divide the x-axis into equally spaced divisions as shown and complete the top of these strips of area in such a way that we can calculate the area by adding up these strips

Simpson's rule is based on a parabolic model of the function to be integrated (that is, instead of connecting 2 adjacent points merely by a straight line, a parabola is chosen such that the curve formed by the joining of these points is extremely smooth and helps in calculating the area). Thus, a minimum of three points and three function values are required. Here we take three equidistant points which being the interval endpoints and the midpoint.

The formula adopted in Simpson’s Rule is as follows where the term f(x) stands for the quantity mentioned along the y direction.

Where sum of odd and even terms do not include the first and the last terms

The main idea to keep in mind while applying the Simpson’s Rule is that, n i.e. the number of intervals must be an even number. Where

Here a and b correspond to the first and the last value of the given interval and h corresponds to equally spaced distance

Consider the example shown below

X	0	1	2	3	4	5	6
Y	99	100	100	101	99	100	100

Follow the below mentioned steps

Step1: Determine if n is even and the interval is equally spaced.
Here there are 6 interval’s namely 0-1, 1-2, 2-3, 3-4, 4-5, 5-6 therefore n=6

Each term varies by a value 1 therefore the value is equally spaced. Hence Simpson’s rule can be applied

Step2: Calculate area
Here a=0, b=6 where a and b correspond to the first and the last value of the given interval
Therefore h=(b-a)/n
=>h=(6-0)/6
=>h=1

Area=h/3*[First value + Last value+4* sum of odd n's of y + 2* sum of even n's of y]
= 1/3*[99+100+4*(100+101+100)+2*(100+99)]
= 1/3*[199+4*301+2*199]
= 1/3*[4*301+3*199]
= 1/3*[1204+597]
= (1/3)*1801
= 600.333

Sheet Sizes, Hydraulic Gradient and other terms

To understand the concept of slope and gradient consider the figure shown below

The above figure represents Gradient where the person walks horizontally 1m for every 1m height this is also told as 1 in 1 and is represented as 1:1.

The above figure represents Slope where the person walks 100m horizontally for every 1m height this is also told as 1 in 100.

Datum

Datum is the point which is obtained with reference to the combination of the vertical scale and horizontal scale when joined at a common point to form a reference coordinate system with reference to which a given quantity is measured on a system. See the figure shown below

To understand as to why datum is to be used, consider the example shown below where the lines start at the value 54.

It can be seen that below the object, lot of space is wasted and hence reducing the readability of the graph. Now if the graph starts at 50 rather than starting from 0 the readability is increased. This value 50 is called datum. This is as shown below

Hydraulic Gradient

Hydraulic gradient is commonly used in irrigation projects while working on canals. Before going to hydraulic gradient let us understand the terms used with reference to the hydraulic gradient by seeing the figure shown below

Hydraulic gradient is a line with a gradient 1:4 which is drawn from canal line to the slope line. If this line drawn from the canal line intersects or touches the slope line then there will be a slip of the canal along the hydraulic gradient line. See the image below

To avoid this slip of ground a berm is drawn on the sides of the canal. There are two types of berm namely Berm and Parallel berm which are shown below

Trapezoidal method

The trapezoidal method is a used to get the area. This is done by inscribing or circumscribing n number of trapezoids and triangles. The areas of the trapezoids and triangles are then summed to get the total area. Before going to the Trapezoidal method in detail first lets us see how the area calculation in done for triangle and trapezoid.

Trapezoidal perimeter
P = b1 + b2 + c + d
= 10 + 6 + 10.2 + 10.2
= 36.4

Trapezoidal Area
A = 1/2 * a * (b1+b2)
= 1/2 * 10 * (10+6)
= 80

Triangle

Triangle perimeter
P = b + c + d
= 10 + 12.81 + 10.2
= 33.01

Triangle area
A = a * b/2
= 10 * 10 /2
= 50

To understand the Trapezoidal method better consider a portion of the cross section shown below.

Here calculations for cutting and filling Area for segments I, II and III are shown below.

I) Segment I between –10 & -5 is a triangle
Formula for triangle = ½ * Breadth * Height
Height = 0.1 (cutting)
Breadth = 5
So Cutting Area = ½ * 0.1 * 5 = 0.25

II) Segment II between –5 & -2 is made of two triangle (as both cutting and filling is there)

Formula for triangle = ½ * Breadth * Height

First find the intersection point:
Depth of cutting = 0.10
Depth of filling = 0.20
Width = 3

Intersection point = -5 + 0.10 / (0.10 + 0.20) * 3 = -4
Width for cutting = 1
Width for filling = 2

First Triangle (Cutting) - 2
Width = 1
Depth = 0.1
So Filling Area = 1 * 0.1 / 2 = 0.05

Second Triangle (Filling) - 3
Width = 2
Depth = 0.2
So Cutting Area = 2 * 0.2 / 2 = 0.2

III) Segment III between –2 & 0 is made of trapezoid

Area of trapezoid = ½ * a * (b1 + b2) / 2
Area calculation for trapezoid = ½ * Width * ½ (Height 1st Line + Height of 2nd Line)

Area of trapezoid (Filling) – 4
Height 1 = 0.2
Height 2 = 0.5
Width = 2

So Filling Area = ½ * 2 * (0.2 + 0.5) = 0.7

Drawing Sheet Sizes

The ISO standard has a specified a wide range paper formats along with their sizes. However not all of them are widely used in practice. Among all formats, A4 is clearly the most important one for daily office use. The following table shows the paper names under Metric names along with the sizes in both inches and mm

Metric Name	mm	Inches
A5	148 x 210 mm	5.8 x 8.3 inches
A4	210 x 297 mm	8.3 x 11.7 inches
A3+	297 x 420 mm	11.7 x 16.5 inches
A3	329 x 483 mm	13 x 19 inches
A2	420 x 594 mm	16.5 x 23.4 inches
A1	594 x 841 mm	23.4 x 33.1 inches
A0	841 x 1189 mm	33.1 x 46.8 inches

To understand the sizes of each paper see the following figure

Further dimension wise all the papers have a relation between them. This relationship with respect to their sizes is shown below

The above figure shows that when two A5 sheets are combines then A4 is obtained. Similarly relationship between all other sheets are shown below

Apart from the above mentioned sheets there are a few more commonly used types which are shown below

Metric Name	mm	Inches
A (letter)	216 x 279 mm	8.5 x 11 inches
Legal	216 x 356 mm	8.5 x 14 inches
B (ledger)	279 x 432 mm	11 x 17 inches
Super B/Super A3	330 x 483 mm	13 x 19 inches
C	432 x 559 mm	17 x 22 inches
D	559 x 864 mm	22 x 34 inches
E	864 x 1118 mm	34 x 44 inches