Feature Line Grading for Small Projects

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Dec 4, 2013 (3 years and 10 months ago)

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Feature Line Grading for Small Projects

John Mayo, PE


CV228
-
3

Small projects have limited funding, so surface models must be created quickly when required. This
course will take an in
-
depth look at creating simplified surface models primarily consisting o
f feature lines for small to
mid
-
sized residential and commercial sites. Gradings and
/or corridors will

be discussed
and utilized
as
complimentary
methods, but the primary focus will be
TIN’s defined with
feature lines. Real project models will be used
to
demonstrate

how to create, label, edit, and manage feature
-
line
-
based TIN

s
.




A
bout the Speaker:

JohnM@ConklinAssociates.com


John is a project manager for a small private sector engineering and surveying firm in Ramsey,
NJ. He first implemented Autodes
k products in his firm in 1999 and has trained all CAD users
on AutoCAD, Map, Land Desktop and Civil 3D. He currently uses AutoCAD Civil 3D, Map and
Raster Design to produce subdivision and site plans for the private sector.


John

is also a consultant who

provides tech support and training classes for Varitronics
Systems in Bound Brook, NJ and is an adjunct professor at the New Jersey Institute of
Technology teaching a 400 level design course for civil engineering students.

2






Introduction

Small projects
are more profitable with simplified finished grade surface models
, data and file
management practices
.

Small projects range from single family home construction, additions
and backyard improvements.
They also include
small parking lot
s, roadway

rehab, shor
t
cul
-
de
-
sac
ro
adway
s

and

small commercial project
s
.
In this course we will look at a number of
ways to produce simplified grading models using
f
eature
l
ines. We will explore
fast and
simple
methods to produce feature lines to model small cul
-
de
-
sac roadwa
ys, single family residential
lots and small parking lots. We will also see how to model retaining walls
,

berms and swales.

This course will concentrate more on the practices and procedures used to
quickly
build
models rather than focus on all of the comma
nds used

to
create
and edit
feature lines.

The Basics

Simplify

and O
rganize

Your Data

Designers should model only features that are required for the project.

The ever popular KISS
principle (Keep it simple stupid
) will save you time and money.
Typically th
is will mean ignoring
fine detail in your models like steps

or
new curb
connections to
roadways

provide soil volumes
won’t be adversely affected
.

Civil 3D labels
and/
or 2d
line work

should be sufficient in m
any

cases

to convey
the design of these items
wit
hout TIN modeling. This will also make design
revisions easier as there are fewer features to edit.

When deciding if a feature should be
modeled designers should question if the feature they are about to

model will affect the design

soil

movement

volumes o
r if the feature is required to display

accurately

in profile or cross
section. If the f
eature does not meet these criteria

there is little reason to model it

if 2d
line
work

or labels can effectively convey the design
.

Tip:

Use an expression to add .125’
to a surface elevation. Place this expression in a surface
label for a drop
/depressed

curb. Place these labels along the gutter line of the curb cut to avoid
drop
/depressed

curb modeling.

External references and data references should be used to man
a
ge the

project

s

drawing files.
No project should have all data residing in a single file
.

Best practices
would
recommend
placing base maps

(existing conditions)
, property lines, surface models and cross sections in
their own files.

Users may consider
maintainin
g
a
single
file with 2d
line work

that depicts the

entire design
.
This 2D file can be used to label FG tin features

like building, wall and pavement elevations
.
3


This is done by noting that Line Labels will work on
feature lines and
polylines in an xref.
Su
rface Reference Text components can link the surface
elevation

to the line and/or curve
labels.
Line and curve labels can be used to create a host of standard plan labels for your
company to report elevations of loading docks, swales, pools/basins and sept
ic fields.
This 2d
file can also be
used to help manage and report bulk zoning requirements like surface cover
s

and building setbacks.


T
ip
:

Use fields in an AutoCAD table to extract the measurement of dimension objects and the
area of
h
atches

to

report bu
lk zoning conditions like surface cover, building setbacks and other
lot dimensions. Note that the area of a hatch can be computed from disconnected areas. Also
note that AutoCAD hatches may not report the hatch area if the underlying geometry has
overlapp
ing or duplicate objects. The hatch command also works best when the hatch
command is working with flat (all elevations zero) base line work.

Redundant tasks can consume profits fast on small projects.
As noted above, typical

Civil
3D
best
practices
recom
mend
placing
surface

model
s in one file and
using
data reference
s to label
the
su
rface
in sheet

files.
This provides a number of benefits including flexibility with labeling
and
following
recommended file management practices for optimal performance
.
With
small
projects designers
should identify and

reduce redundant labeling tasks

in their workflows
.

For small project user may also consider using the FG surface file in the plan sheets to
depict
contours and
label

all FG features. This is done by n
oting agai
n that
Civil 3D L
ine and
C
urve
labels work on feature lines and polylines in an xref.

Note:

Drawing performance
will decrease if a file

becomes overloaded with labels
and
AEC
objects
which are re
-
calculated with each regen of the
display
. Minimizing labels

will help
insure optimal
performance.

2
d

to 3
d

Small projects are often drafted in 2d
using AutoCAD lines, arcs and/or polylines
prior to
grading in order to
analyze and refine
bulk zoning requirements.
Designers can simplify the
modeling process
utilizi
ng

a 2
d

to 3
d

approach.
In this process users simply
convert existing
linework into feature lines and
assign
design elevations.

Use the Insert command to bring
previously created 2d
line work

into a new dwg file to
begin

the modeling process. If XRef’s are

being used, the NCopy
and Boundary commands
can be
used to create the 2d
line work

in the new file. This
line work

can now be converted into feature
lines using the Create

Feature

Lines
from Objects
command
.
This command is found on the
Home tab of the Ri
bbon by selecting Create Feature
L
ines
f
rom
O
bjects in the Feature Line
drop down menu of the Create Design
panel
.

4



Tip:

The AutoCAD Boundary and Hatch commands work best with flattened
line work

(Z = 0)
that does not
have
duplicate
objects
, overlapping s
egments or zero length objects. The
Mapclean command can be used to remove these

and other negative

geometric conditions.

If a user selects a feature line in the drawing window the Feature Line Contextual Ribbon will
appear and this Ribbon tab will have a
ll of the tools required to assign Z values to the 2d
line
work
. To be more specific, the Elevation Editor,
Set Grade/Slope Between Points

and the
Feature

Elev
ations f
rom

Surf
ace

commands are a good place to
refine

the 2d to 3d process.


B
est Practices

Be
st Practices should be followed to insure drawing stability and optimal performance.
Autodesk has included Best Practice white papers in the Civil 3D Help files. Designers using
feature lines should be familiar with Best Practices for Grading and Sites.

T
ip
:

Select the Help dropdown on the Info Center Toolbar and select Learning Resources to
access the online Best Practice manuals.

5



Tip:

If this document discusses a command you would like to learn more about, search the
online Help files for more informat
ion. Also note that a good internet search engine is another
good way to learn more about specific Civil 3D commands and processes. Searches can even
be release specific if the release year is typed in the engine after Civl 3D.

For example typing in
‘Civil

3D 2009’ into Google with the quotes along with a question will
typically
return results for
the 2009 release.

Noteworthy
P
ractices
f
or
F
eature
L
ine Models

1.

Audit and Save often.

Save before attempting 3D Orbits. Use saved views to reduce real
time graphic
s processing.

2.

Use multiple sites. Placing all of a project

s feature lines into a single site is not
recommended for optimal performance as every feature line needs to be computed for
interaction during each regen or surface build. Designers can force feat
ure lines
that are
on
different sites to interact by temporarily mov
ing

them to the same site

(right click on the
Feature Line and select Move to Site)
. After the feature lines

react with each other and find

common Z value
s
, they can be move
d

back to the
ir

original site.

3.

When converting 2d line work (lines, arcs, 2d and 3d polylines) to feature lines
use
Mapclean or Overkill to remove undesirable geometric conditions like overlapping objects
and zero length objects. A
void overlapping objects if the resultin
g feature lines will reside
on the same site.

4.

Minimize feature line
PI’s and elevation points to maintain optimal performance. Use the
Feature

L
ine Weed command to keep feature lines free of unnecessary
vertices
. Also
when
adding feature lines to a surfac
e as breaklines,
minimize
supplemental distances and
maximize
weeding and
mid ordinate distances when adding feature lines to a Civil 3D
6


surface
. This will help minimize
surface data points. Excessive
feature line and
surface
data points can degrade perfor
mance.

When

adding breaklines to a surface the user is

presented with the dialog box below,
hover your cursor over the dialog box and
hit the F1
button to learn more about these features.



TIP
:

The technique used above to easily locate the Help
pag
e

for the Add Br
eaklines dialog
can be used on

most of Civil 3D’s user input dialogs and
Ribbon

buttons.

Simply place your
cursor over any
Ribbon
command
button or dialog box
and hit the F1 key to have Help open
the
appropriate page
for that command

or dia
log
.

5.

Avoid Split Points

if they are not needed
. Split points occur when feature lines residing in
the same site cross each other. The last feature drawn will assign a new elevation to the
previously drawn
feature line at the crossing point
. Avoid split poi
nts by placing elevation
points
or PI’s
at feature line crossings.

6.

When using the AutoCAD Move command to displace Feature Lines, be sure to maintain a
constant elevation during the move. Autodesk does not recommend using the AutoCAD
Move command to change

Feature Line elevations. Save your file before using the
AutoCAD Move command and run Audit immediately after to insure drawing stability.

Tip
:

To maintain a constant Z when moving feature lines either
input coordinates at the
command line,
set the OSNAPZ

system variable to 0 or restrict object snaps to zero elevation
objects

only
.

7.

Vertical faces are approximated in Civil 3D using small horizontal offsets between the top
and bottom of vertical
faces

(0.10 or 0.05 units work well in most situations
. Using t
rue
vertical faces in a TIN model will result in surface errors.
)

Creating
Surfaces

with Feature lines

7


Simple
Residential

Lot

Grading

A simple residential lot can be modeled

quickly
with a handful of feature lines.
Further detail can
be added simply by add
ed new feature lines. In th
is

example a residential lot will be quickly
graded and then a wall, berm and swale will be added as additional features. The FG surface
will also display a slope analysis so the designer can monito
r proposed grades dynamically.

1.
Begin with these small projects with 2D polylines to represent the building, left and right
driveway edges
,

and a limit of disturbance
/grading
.

The limit of disturbance is approximated
around the site

based on a reasonable residential yard, tree remova
l and/or expected
tree
removal or grading
.
It is used to help form a rough surface and connect the contours across the
site

through the buildin
g and driveway similar to how an

engineer

would approach a ‘red
-
line
d

plan that depicts a ‘contour design’

witho
ut a CAD application
.

In this example the lot owner is expected to landscape or install sod from side lot line to side lot
line and from the back of curb line to a backyard approximately 100’ from the rear of the
building.

Insu
re the
se polylines do not ov
erlap.
Use the
Insert PI command on the Edit Geometry panel of
the Ribbon’s Modify tab to create additional polyline
vert
ic
es
on the building where the

driveway
line
s intersect

and where the back of curb polyline intersects the driveway.
This will help avo
id
split points in the feature lines that will be created for the back of curb line.

It will also help
assign elevation to the endpoints of the driveway base on the EG at the curb and our design
elevations on the building.


2.
Convert the driveway line wor
k to Feature lines. Do not assign elevations to these features
yet. The endpoints of each side of the driveway will automatically get elevations from the
building and curb connection once those feature lines are created and raised to design
elevations.



8


3
.
As noted in step 1 above, approximate a reasonable limit of disturbance/grading based on the
project design criteria. Since this is where the dozer will stop, this line will be common to both
the EG and FG surfaces. Convert this polyline into a feature
line using the Create Feature Lines
from Objects command. Assign elevations to this feature line from the EG surface.

4
.
Convert the
back of

curb polyline to a feature line and assign elevations from the EG surface.
This operation will assign elevations to

the endpoints of the

connected

left and right driveway
edges.

5
. The polyline drawn for the building represents the finished grade line

around the building
(where the dirt hits the

building
)
.
Offset this polyline .05 units inside. The interior polyline wi
ll be
used to represent the basement

or lowest

floor
. This polyline or feature line can be used to label
the lowest floor elevation in plan, profile and section

views

(more on this in profile and sections
latter)
.

In this example the first floor is placed
about 2’

above the roadway
at
elevation
344
.
The
basement is 12’ deep
with the garage two step below the basement. As per the architectural
plans
th
e
building
grade line
should be about

2’ below the first floor
(elv.
3
42
) and ru
n down to
meet a ‘garage und
er’ and a ‘w
alk
-
out
-
basement


design
. Convert both polylines into feature
lines and assign desired elevations to the building grade line (outer polyline) and to the
basement (inner polyline).

Once elevations are assigned to the
back

curb and the building

grade line

all driveway endpoint
elevations are assigned
if the feature lines are on the same site. The

Set Grade/Slope Between
Points

command or the elevation editor

can be used to assign constant grade from endpoint to
endpoint of each driveway line to g
et a basic design. Further elevation edits to the parking area
can be made if desired and the cross grade can be leveled with simple non
-
plotting construction
feature lines. Draw these construction lines between the sides of the driveway and endpoints of
t
ang
en
ts and/or curves as required to force any desired cross grade
.

If a crown is required
a

stepped offset
can be used
to f
or
m the crown.

9



8.

Place the feature lines created above into a surface definition as breaklines.

Apply a
surface style that displays
the surface contours.

The contours will fill in across the site and
the rough surface can be examined for further revision.
With Auto Reb
uild turned on for the
surface
further feature line edits will be automatically displayed in the FG surface’s
contours.

Simple residential lot surfaces can be formed in minutes with feature lines when beginning with
existing 2d line work.



Checking Design Slopes with Feature Line Models

Apply a surface style that depicts contours and slopes. Perform a slope analysis to m
onitor
critical grades. In this example all finished grades must be less
th
an 33.3% and the slope
analysis has one range for slopes greater than 33.3%. In the image below the red area
10


depict
s

slopes greater than our design criteria. A retaining wall will b
e used to reduce the
proposed grades.


Retaining Walls

In the process above the designer may note that contours bunch up and form steep slopes in
certain areas of the proposed surface.
Often

this indicates a retaining wall is required to
maintain desired
design slopes.
If r
etaining walls are
required the
y

can
easily
be
modeled us
ing
two or three feature lines.

1.

Draw

a feature line along the bottom of the wall for a fill condition or

the top of a wall in a
cut con
dition.

Assign elevations to the feature line

from the EG surface
.

2.

Use a stepped offset to create the corresponding top or bottom of wall at the desired
elevation difference.

Weed this feature line of unnecessary elevation points.

3.

Use the
Set Grade/Slope Between Points

command or the
E
levation
E
ditor

to
assign the
desired design elevations to the offset feature line. If required, edit the ends of this
feature line to meet the feature with EG elevations at desired design grades. This
insures that top and bottom of wall grade meet at the each end of the

wall.

4.

A third feature line can be used to provide a model that will better display the wall in
surface profiles and sections. This will typically be formed with
a
stepped offset

of the
top of wall just inside the bottom of wall.

Designers may compute hori
zontal offsets
based on design specifications for wall batter.

I
f

this is not required a horizontal offset of
0.1 units will
be sufficient

for approximating most vertical faces.

11



Berms and Swales

Berms and swales can
also be
quickly
modeled wi
th a few fe
ature lines
.

1.

Begin by drawing a
Feature Line along the
centerline path
,

assigning elevations from the
surface that the berm or swale will be created on. Insert elevation points at desired
design points if required and use the
Set Grade/Slope Between Point
s

or elevation editor
to adjust the centerline elevations.

2.

Use a stepped offset with an elevation difference of zero to form the sides
of the berm or
swale. An arc feature line can be drawn

to connect the two side
s

of the berm
or swale
to
help form smoothe
r contours if required.

3.

Select the feature line that represents the centerline and right click. Select Raise/Lower
and raise the centerline for a berm or lower it for a swale to the desired height or depth.

4.

Add the feature lines created above to the surfac
e. A stepped offset can again be used
to
for a top bank for the berm or
provide different contour patterns.

12



Finished Floor Elevations

In the example above two feature lines were easily constructed to provide a means of labeling
the lowest floor or baseme
nt for this home. This also allows the basement cut to be computed
in surface volumes. One more stepped offset will provide users with all they need to have the
finished first floor labeled in plan, profile and sections if required. Simply use a stepped of
fset to
create a new feature line 0.05 to 0.10 units inside the lowest floor. Raise the feature line to the
first floor elevation. This feature line and the basement feature line can now be labeled with line
labels to depict the plans proposed floor elevat
ions. Create a new surface called BLD and add
the feature lines for the basement and first floor as breaklines. Use the basement feature lines
as an outer border on this surface and it can be sampled as a profile and cross section that can
also be labeled
for plan sheets.

Here are some examples of line labels placed on feature lines. There are no AutoCAD test
objects or leaders in this image depicting a new home (cyan) driveway (white), patio (white)
retaining walls (orange), septic field (purple) and pool
(blue). All labels describe the feature line
and provide the appropriate start or end z segment value. For example one label reads, ‘PATIO
ELV 346’ another reads, ‘F.F.F: 360.0’ to label the finished first floor in plan and section.


Simple

Cul
-
de
-
sac
s an
d Roadways

13


Small roadways and cul
-
de
-
sacs can easily be modeled with feature lines if an alignment and
profile have been constructed.
A 2d polyline
representing

the
roadway centerline and the
cul
-
de
-
sac gutter

line or
bottom of curb
are also required
.

TIP
:

To create a polyline from a Civil 3D Alignment, use the AutoCad Offset on the alignment.
This will create a polyline. Use the Offset command once again to offset the polyline above
back onto the alignment if required.

As stated above
,

begin with a centerl
ine alignment and layout a profile for the finished vertical
grade. A simple corridor will be used to project a plane representing the pavement surface

past
the curb line
.
The assembly used below
is constructed with

a left and right generic
LinkWidthAndSlo
pe subassembly with a 2% cross grade down to the gutter.


A corridor surface is then used to project elevations to the cul
-
de
-
sac gutter line.

TIP
:

Although very limited

with Civil 3D
,
AutoCAD Fields can extract some Civil 3D object data
like the names of

the assembly and subassembly above.



Stepped offsets are used to create the top of curb and the finished grade line along the right of
way. Create a grading along the right of way grade line
to daylight from the right of way
to the
EG surface.

14



Create
a new
grading
surface

from the grading object
. To complete the FG roadway model a
dd
the feature lines
for the centerline and curbs

into

the grading surface
.


Note that this procedure will produce a model that is not fully dynamic as a properly modeled
cor
ridor

would be
. For this reason it should only be used on small roadways

that are not
expected to undergo a large

number of revisions
. If revisions are required,
erase
the grading
and all

of the breaklines except the centerline and bottom of curb. Edit the

alignment or profile
as needed. P
roject new elevations to the centerline and gutter and
then
rebuild the remaining
features.

Users should also maximize corridor frequencies in order to minimize the elevation
points assigned to the bottom of curb feature l
ine.

In this model all corridor frequencies were
set to 25’.

15


TIP
:

Many of the Feature line editing tools and the Create
Feature

Lines from Objects
command permit multiple selections for mass editing. Read the Dynamic Input Cursor or
command line before mak
ing a selection and the user is prompted for
Multiple

selections
.

Parking L
ots

A simplified planar corridor and corridor surface that extends past the proposed parking lot can
also
be used to mass grade
feature lines for
commercial lots
.

In the example bel
ow

the

primary grading objective

was to
raise the lot without exceeding 2
.5
’ of
fill on

existing grade
. This was
done in
an effort to keep the
proposed
stormwater management
system above seasonal high groundwater. T
he parking
lot
and drainage
became a larg
e

factor
in the design process. T
he building floor elevations

were desired to be above the road if
possible

and the site was expected to be mass graded.

The

alignment and p
rofile were designed to meet

county roadway connection requirements

and
care was ta
ken to match the proposed centerline to the existing roadway gutter line
. The

alignment and profile were extended
past

the rear
curb line
of the
parking
lot

trying to raise the
grade in the center of the lot
. A crown
was

placed on the centerline
to divert
water to both sides
of the lot

in this example but t
he crown is optional and the subassemblies can form a crown,
valley, flat or sloped plane as
required

for the project at hand.



A corridor
and

corridor surface w
ere

constructed
with an assembly containi
ng
a left and right
LinkWidthAndSlope subassembly
. The subassemblies
extend

past
both of
the proposed
side

curb

lines
.


16


Th
e

corridor surface
will be

used to
project elevations to the

bottom of curb

Feature Line
.

Since
this lot was previously laid out in 2d

for zoning, we will use the previously mentioned methods to
import the 2d line work, convert them to feature lines and assign elevations.



If required th
e feature line

for the bottom of curb/gutter line
can be edited to meet other design
criteria.


Tip
:

If the WeedFeatures command removes the curves from a feature line, use the Partial
weed option (read the command line after executing WeedFeatures) and weed the feature in
segments from PI to PI or try breaking the feature line into smaller segments.

Add

the bottom of curb
to a
new
FG
surface as a breakline.
Now we need to define the
pavement crown.

Select the surface and the Modify Corridor Ribbon Panel is displayed. Use the Feature Lines
from Corridor command to display the Feature Lines from Corridor d
ialog box. Since the crown
we want to model is shorter than the corridor we need to uncheck the Create Dynamic Link to
Corridor button. Assign the correct site and feature line style to create the pavement crown.
Select the resulting feature line and trim
the pavement crown to the rear curb line.

17



A volume surface
ca
n
be

created displaying cut/fill elevation banding to help identify fill heights
greater than 2’ since we have yet to model the top of curb. If the elevation banding shows the
pavement surface
is to
o

high, the profile can be revised to lower the FG grades. If auto rebuild
is turned on for the corridor and the FG surface, the profile edits will automatically be shown in
the plan view contours once the new elevations are assigned to the
feature li
nes
.

Once the
pavement surface is below the 2’ design criteria the elevation banding will disappear even
though the surf
ace is still in the drawing
.


18


Once the pavement surface design is acceptable
a
stepped offset
is used to

create
t
he
corresponding
top
o
f curb.

A building grade line and first floor elevation can be evaluated by
identifying the surrounding curb elevations. Convert the building polyline into a feature line and
assign elevations. If a basement is desired to

be

modeled, use a stepped offset t
o create a new
feature line inside the building grade line and assign the basement elevation
s

to the inside
feature line.

Tip:
If basement and first floors are required to be shown and labeled in profiles or cross
sections

create a surface for your buildin
g
. Create a third offset inside the basement or lowest
floor feature line. Assign elevations to represent the upper floor and add the lowest and highest
floor feature lines
to this new surface
. Also add the
lowest floor feature line

as a surface border
if
required. T
his surface can be
now be
sampled and labeled in profiles and cross sections to
display floor elevations.

See the image on the cover of this handout to see a modeled building
for this project.

Convert the remaining polylines into feature lines f
or the walkways. Since the walkways all
connect to the building or curb designers can easily obtain
start

and/or end
point elevations
simply by placing the resulting new feature lines on the same site as the feature lines already
created.

The
Elevation edi
tor and/or the Set Grade/Slope Between Points
command can be
used to fine tune the walkways.

If elevations to the curb are lost in the converting process
simply reassign the corridor surface elevations.

A grading object can be used to find a daylight line
for the lot but since this lot will be mass
graded we can try to simplify the model again by adding an estimated limit of grading feature
line into the model. In this example the property lines
and back of existing curb
correspond to
the limit of disturban
ce an
d

can simply be made into feature lines with EG elevations using the
Create Feature line command

or other methods discussed earlier
.

The model is
completed

by adding all of the feature lines into the FG surface and also adding
the limit of disturbance

feature line as a border.

19



Swapping surface edges and surface smoothing can be used
to
smooth jagged contours. Th
e
se
tools can be found by selecting the FG surface which will display the Edit Surface Ribbon tab.
Proposed
slopes can be monitored with a
TI
N
volume
surface

and slope triangles as discussed
earlier.

Tip:

If surface smoothing is used and does not provide results to your liking or is crashing refer
to this webpage from the always helpful folks providing us the ‘Being Civil’ blog.

http://beingciv
il.typepad.com/my_weblog/2010/10/surface
-
smoothing
-
crash.html

Note
s
:


1.
Mass grading
feature lines
with

planar surfaces is not
new
to Civil 3D.
The process has been
implemented in Land Desktop and other software packages.
There are a number of great
tutor
ials online

that provide similar processes

for projects that assist

designer
s

who
want to
grade from a build
ing line outward to curb lines
.

In many of these processes corridors are often
replaced with gradings to create planar surfaces. This is done becaus
e corridors don’t have a
miter feature like gradings do
which

produce radial daylight lines from tangent intersections on
base featur
e lines.


2. Many designers prefer to

design from the top of curb. The processes used for the simple
roadway and commercial

grading are easily modified for this design preference.

Summary

Feature lines can be a highly effective object to quickly create
TIN

models fo
r small projects.
Small project

models should be simplified and labels should be used to minimize the time spent
grading and conveying the grades to your plan sheets. The methods demonstrated in this class
20


to create many common site improvement features can be used and modified to
work on a
variety

of small commercial and residential projects.

Care should also be tak
en to minimize
surface and drawing data.

Troubleshooting and Preventing
issues in feature line based drawings.

1.

As previously mentioned
, when converting AutoCAD objects to
feature line
s

it is
important to use polylines that do not contain errors like overla
pping segments or
zero
length geome
t
r
y
. Use Mapclean
and/or Overkill
to remove

the
se

geometric conditions
and insure that converting these objects to feature lines will not cause issues.

2.

Avoid overlapping feature lines unless they are on separate sites.

3.

Sa
ve
and Audit your drawing
often. Use Recover on drawings that crash.

4.

Use Audit after using the AutoCAD Move command on any Feature lines. Remember
that the AutoCAD Move command should not be used to edit or change any feature line
elevation
s
.

5.

Minimize surf
ace data points as described in the methods above to maintain optimal
performance. Remember that drawing performance can be reduced when drawings
become bloated with computational data like excessive feature line nodes
,
excessive

labels

and small
corridor
fre
quency settings.

6.

Two undocumented commands in the 2010 and 2011 releases can be used to help
identify drawing issues related to feature lines. FindSiteOverlaps and

RemoveDupFeaturelines

can be typed into the command line to help identify potential
drawi
ng issues.



Please note that all attendees are highly encouraged to complete
and return
the
speaker evaluation form.