elements_of_super_alignment_design.pdf

8/9/2019 Elements_of_Super_Alignment_Design.pdf

1/14

Extra Dimension Solutions

Alignment Design using

Super Alignments

12d Model Course Notes

FIXED

FLOAT

FLOAT


2/14

Alignment Design using Super Alignments

Version 1.0 August 2006 Page i


12d ModelCivil and Surveying Software

Table of Contents

1111 WHY ALIGNMENT STRINGWHY ALIGNMENT STRINGWHY ALIGNMENT STRINGWHY ALIGNMENT STRINGS?S?S?S? ............................................................................................................................................................................................................................................................................................................................................................................................ 11111.1 ALIGNMENT STRINGS ARE SPECIAL........................................................................................... 1

1.2 TRADITIONAL ALIGNMENT DESIGN ........................................................................................... 11.3 ELEMENT BASED DESIGN (PARAMETRIC DESIGN)........................................................................... 11.4 SUPER ALIGNMENT ........................................................................................................... 1

2222 ELEMENTS USED IN ELEELEMENTS USED IN ELEELEMENTS USED IN ELEELEMENTS USED IN ELEMENT BASED DESIGNMENT BASED DESIGNMENT BASED DESIGNMENT BASED DESIGN ................................................................................................................................................................................................................................................................................................ 22222.1 FIXED ELEMENTS .............................................................................................................. 22.2 FLOATING ELEMENTS ......................................................................................................... 22.3 FREE ELEMENTS............................................................................................................... 2

3333 CREATING A SUPER ALICREATING A SUPER ALICREATING A SUPER ALICREATING A SUPER ALIGNMENTGNMENTGNMENTGNMENT .................................................................................................................................................................................................................................................................................................................................................................... 33333.1 CREATE A NEW ALIGNMENT AND ADD PART 1 - A FIXED PART. .........................................................33.2 PART 2 - FLOAT AN ARC OFF THE STRAIGHT............................................................................... 53.3 EXERCISE 1 EDIT THE ALIGNMENT ........................................................................................ 73.4 PART 3 FLOAT ANOTHER ARC. ............................................................................................8

3.5 CHANGING HOW THE PARTS ARE DEFINED.................................................................................. 93.6 DESIGNTRICKS FOR SUPER ALIGNMENTS ................................................................................ 12

4444 THE DESIGN STYLETHE DESIGN STYLETHE DESIGN STYLETHE DESIGN STYLE (HOW THE ALIGNMENT(HOW THE ALIGNMENT(HOW THE ALIGNMENT(HOW THE ALIGNMENT LOOKS)LOOKS)LOOKS)LOOKS) ............................................................................................................................................................................................................................................ 131313134.2 EDITING THE DESIGN STYLE................................................................................................ 15

5555 SUPER ALIGNMENTS FORSUPER ALIGNMENTS FORSUPER ALIGNMENTS FORSUPER ALIGNMENTS FOR SUBDIVISIONS & ESTASUBDIVISIONS & ESTASUBDIVISIONS & ESTASUBDIVISIONS & ESTATESTESTESTES....................... ............................................................................................................................................................................................................................. 161616165.1 USING THE SAME AS TOOL.............................................................................................. 165.2 EXERCISE MOVING THE FIXED ELEMENT................................................................................. 185.3 DESIGNING ROAD 2 USING THE SAME AS COMMAND................................................................. 195.4 A FLOATING STRAIGHT AT THE START OF ROAD 2....................................................................... 225.5 EXERCISE - FINISHING ROAD 2............................................................................................ 255.6 EXERCISE ROAD CENTRELINE FOR ROAD 1 ............................................................................ 26

6666 VERTICAL DESIGN USINVERTICAL DESIGN USINVERTICAL DESIGN USINVERTICAL DESIGN USING ELEMENTSG ELEMENTSG ELEMENTSG ELEMENTS........................................................................................................................................................................................................................................................................................................................................ 27272727

6.1 VERTICAL DESIGN OF ROAD 1 ............................................................................................276.2 VERTICAL DESIGN EXERCISE FOR ROAD 1................................................................................ 286.3 VERTICAL DESIGN FOR ROAD 2...........................................................................................29

7777 VERTICAL DESIGN USINVERTICAL DESIGN USINVERTICAL DESIGN USINVERTICAL DESIGN USING INTERSECTION POINTG INTERSECTION POINTG INTERSECTION POINTG INTERSECTION POINTSSSS........................................................................................................................................................................................................................................................................ 313131317.1 DESIGN GRADES FOR ROAD 2 ............................................................................................317.2 DESIGN VERTICAL CURVES FOR ROAD 2.................................................................................367.3 EDIT THE VERTICAL DESIGN IN ATABLE ................................................................................... 37

8888 COMPLEX HORIZONTAL DCOMPLEX HORIZONTAL DCOMPLEX HORIZONTAL DCOMPLEX HORIZONTAL DESIGNESIGNESIGNESIGN THE VISIBLETHE VISIBLETHE VISIBLETHE VISIBLE TICKBOX. TICKBOX. TICKBOX. TICKBOX......................................................................................................................................................................................................................... 39393939

12d Model Course NotesThese notes were prepared by

Tony Ingold

These notes may be copied and distributed freely.

These notes may NOT be used as the basis for a course of formal instruction without written permission from Extra Dimension Solutions Pty Ltd

Extra Dimension Solutions is an authorised distributor of 12d Model in NSW the ACT and SA

Disclaimer

12d Model and are supplied without any express or implied warranties whatsoever.

No warranty of fitness for a particular purpose is offered.

No liabilities in respect of engineering details and quantities produced by 12d Model are accepted.

Every effort has been made to ensure that the advice given in these notes and the programs 12d Model are correct, however, no warranty isexpressed or implied by 12D Solutions or by Extra Dimension Solutions.

Copyright Extra Dimension Solutions Pty Limited 2006All rights reserved


3/14



Course Notes Version 1.0 August 2006 Page 1


1 Why Alignment Strings?

1.1 Alignment strings are special

Alignment strings are usually used to design road centrelines.

Alignment strings are different from other types of strings:

The vertical geometry is independent from the horizontal geometry.

The plan position of the string does not alter the vertical design (for example you could

horizontal points and the vertical design would not change).

The horizontal design and the vertical design can be of different lengths.

You can drag the vertical design elements in the section view.

1.2 Traditional Alignment Design

When road centreline design was done by hand, the designer would use a long straight edge and a

pencil to draw the straight parts of the road onto a plot of the survey. The straights would run

between Horizontal Intersection Points or H.I.P.s

Curves would be drawn between the straights using Railway Curves. The points where the curve

touched the straight was called the tangent point (T.P.). At this point the curve and the straight are

tangential to each other, (they have the same bearing).

This traditional method of design using I.P.s has been available in 12d Model for many years.

1.3 Element Based Design (Parametric Design)

The drawback to using the I.P. method for alignment design is that the only way you can define a

curve (maybe a kerb return) is by using three I.P. points to create two straights, then to create a

curve between the straights. This works fine until the position of the curve needs to be edited. It is

easier to delete the curve and start again.

Element Based Design allows you to define the curve by (say) three points. Or by a centre, radius,

and the start and end points. There are no I.P.s

1.4 Super Alignment

12d Models Super Alignment allows you to use both Element Based design and I.P. based designin the same alignment string. You can design the horizontal geometry using I.P.s then use elements

to design the vertical geometry.


4/14





2 Elements used in Element Based Design

2.1 Fixed ElementsFixed Elements are parts of the alignment that are locked in. A straight between two points and a

curve through three points are both Fixed Element. There is no debate about where they lie once

the points are chosen.

A Fixed Straight could also be defined by choosing a point and specifying a bearing. While the

length of the straight is unknown, there is no debate about where it lies.

TYPICAL FIXED ELEMENTSStraightsStraightsStraightsStraights CurvesCurvesCurvesCurves

- Two points - Three points

- Point and bearing - Centre, radius, start & end points.

2.2 Floating Elements

Floating elements are parts that need to join on to ONE fixed part of the alignment.

TYPICAL FLOATING ELEMENTSStraights:Straights:Straights:Straights: Curves:Curves:Curves:Curves:

- You choose oneoneoneone

pointpointpointpoint. The straight

must pass through

the point

12d Calculates12d Calculates12d Calculates12d Calculates

ONE tangentONE tangentONE tangentONE tangent

pointpointpointpoint. The

straight passes

through the T.P.

- You choose twoYou choose twoYou choose twoYou choose two

pointspointspointspoints. The curve

must pass through

the two points.



pointpointpointpoint. The curve

passes through

the T.P.

- You choose a

bearingbearingbearingbearing.



pointpointpointpoint. The

straight passesthrough the T.P.

and has the

bearing you

chose.

- You choose oneYou choose oneYou choose oneYou choose one

point and a radiuspoint and a radiuspoint and a radiuspoint and a radius.

The curve must pass

through the pointand have the radius

you choose.



pointpointpointpoint. The curve

passes throughthe T.P. and

uses the point

and radius that

you chose.

In all cases you do not provide enough information to accurately position the

straight or curve. 12d Model12d Model12d Model12d Model must calculate ONE tangent pointONE tangent pointONE tangent pointONE tangent point, before the

curve or straight can be created.

2.3 Free Elements

Free elements are parts that need to join on to TWOfixed parts of the alignment.

Free Elements

Straights: Curves:

- No points 12d Calculates12d Calculates12d Calculates12d Calculates

TWO tangentTWO tangentTWO tangentTWO tangent

pointpointpointpoints.

- One point 12d Calculates12d Calculates12d Calculates12d Calculates

TWO tangentTWO tangentTWO tangentTWO tangent

pointpointpointpoints.

- Centre, radius,

start & end points.

In all cases 12d Model12d Model12d Model12d Model must calculate TWO tanTWO tanTWO tanTWO tangent pointgent pointgent pointgent point, before the curve or

straight can be created.


5/14





3 Creating a Super Alignment

3.1 Create a new Alignment and add Part 1 - a Fixed Part.

Fill out the panel, and press Createto open the Alignment Editor.

Press the Properties button(the fourth button)

Press the Type button and

choose Lines=>Fixed

Highlight

then press Insert.

Use Strings=>Create=>Alignment=>Super Alignment.


6/14





Enter the coordinates of theStart & End of the line as

shown, then press Set.

The Part of the alignment iscreated, and is displayed..

The grid can be displayed on the

view using toggle button.


7/14





3.2 Part 2 - Float an Arc off the Straight

Highlight

then press Insert.

Enter the coordinates of thetwo points on the arc asshown, then press Set.

When you press Set 12d Model calculates

the tangent point of the curve that joins

Part 1 and passes through the two points.


8/14





Notes: ________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

The arc goes through the two points that

you chose and through a third point that12d Model has calculated to make the arc

tangential to the straight.


9/14





3.3 Exercise 1 Edit the Alignment

1. Use the move button to move the points which define the alignment.

2. Move the mid point on the arc so that it is above the line as shown.

3. Use the Undo button the undo your changes.

Control points on the Alignment canbe edited using the Move button.

The alignment cannot be Solvedwith the two curve points arranged

like this, and the X indicates thatthe Alignment needs your attention!

Undo your Move commands with the

Undo button.

While you are editing the Alignment,

the Alignment Editor contains all of

the editing tools that you need.

If youre not sure what this means, then trysketching a curve which is tangential to the

straight, and which goes through the two points.


10/14





3.4 Part 3 Float another arc.

Highlight

then press Insert.

Enter the coordinates of theend of the arc and theradius, then press Set.

Choose element typeArc: Floating radius

If you highlight Part 2, the new Part will be

inserted after Part 2. The new Part always goesbelow the Part that you have highlighted.

FIXED FLOAT

FLOAT

Note that Part 2 does not go through its

second point now. The point is still required

to define Part 2, and the shape of the

alignment will change if you move this point.


11/14





3.5 Changing How the Parts are Defined

We want to change the radius of Part 2.

BUT THIS PART WAS NOT DEFINED BY RADIUS!

We will change Part 3 to a FIXED element, THEN

change Part 2 to an FREE Element.

Choose Part 3 of theAlignment, and change it to

a Fixed element.

Press the Same as button fromthe bottom of the panel, and pick

Part 3 off the screen.

Part 3 was defined in 3.4 above as an arc

with a given that passes through a point.

Will change the definition so that it is a

FIXED arc with a known centre and radius,

and fixed start & end points.


12/14





Notes: _________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

Part 3 is now defined bycentre, radius, and the

start & end of the arc.

The Alignment looks good, but looks can be deceiving. All of the elements are

tangential, but this is simply good luck. If any of the points that define the alignment

change, then 12d Model cannot adjust the other parts to keep that tangency.

The alignment is too constrained, it does not have enough freedom.

You will see this if you use move the centre of the Part 3 arc.

You correct this we must make another Part more free.


13/14





_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

Define Part 2 as a FREE element,with a given radius.

Use the same steps to change Part 2so that it is defined as FREE RADIUS.

The key here is to use the Sameas button.

We can change Part 2 so that it is defined as

a Free element, and make it the Same as

itself when it is defined as a Floating element.


14/14





3.6 Design Tricks for Super Alignments

You have used the two most common methods of design in Element Design.

You will find yourself using combination of fixed, floating and free elements in two main combinations:

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

FIXED

FIXED FIXED

FLOATING FLOATING FLOATING

FREEFREEFREEFREE FREEFREEFREEFREE FIXED

elements_of_super_alignment_design.pdf

Documents