Lesson 4: Intersections and Subdivisions

1   Click the icon for Carlson and start up Carlson Software from Windows. Once in the program, exit the Startup Wizard if it appears.

2   Once in Carlson, click Open under the File pulldown menu. Look for the file Plat4.dwg and click on it. When it lights up blue, as shown below, it will appear in the Preview Window at right. It should look like the open-sided property shown here. Plat4.dwg is found within the WORK folder of Carlson. You search for the file as you typically would in Windows, clicking the yellow "Up one level" button to go to the parent folder of the current folder, or by clicking the adjacent down arrow to find the desired path in the full tree of folder locations.

Now click Open to select and open the file Plat4.dwg.

3   Enter & Assign a Starting point for the Street Centerline. Select Draw-Locate Points, found under the Points pulldown, and obtain the dialog shown below:

Click off the prompting and labeling for Descriptions, Elevations and Locate on Real Z Axis (make them blank as shown). Up top, change the symbol to SPT10 by picking Select at the very top of the dialog, and choosing symbol SPT10 from the dialog of symbol choices (not shown here). Also, verify that Automatic Point Numbering is clicked on, that the Starting Point Number is 1, that the layer is PNTS. Match these entries (which are mostly the default conditions) and click Enter and Assign at the lower left.

Prompting will appear at the bottom of the screen. We will enter the starting point as follows:

Enter North(y): 4809.17
Enter East (x): 4391.28

The program will recognize that you have not yet started a coordinate file, so click the New tab and enter the File Name as Plat4.crd (which should be the default). If you enter Plat4, you do not need to enter the extension .crd. The program will add extensions automatically. You will see this:

Click Open. You will be prompted again:

Enter North(y): press Enter (for no more points; we are done)

4   Traverse from PI to PI (to the two endpoints of our centerline). Select Traverse under the COGO menu, or alternately just enter T at the command line. (T is a hot key. Other hot keys are I for Inverse and SS for Sideshot). Reply to the prompts as follows:

Traverse, Line OFF, RAW FILE OFF
Exit/Options/Arc/Points/Line/SideShot/Inverse/Angle-Bearing Code <7>: 1
Enter Bearing Angle (dd.mmss) <90.0000>: 58.1848
Points/<Distance>: 736.73
N: 5196.15  E: 5018.19  Z: 0.00
Exit/Options/Arc/Points/Line/SideShot/Inverse/Angle-Bearing Code <1>: E (to exit)

5   Line On/Off. Click Line On/Off, under the COGO menu, to turn on simultaneous linework with traversing. This command toggles on and off each time you click it, with the On status indicated by a check mark. Now repeat the Traverse command. Try T for Traverse this time, entered at the command line.

Traverse, Line ON, RAW FILE OFF
Exit/Options/Arc/Points/Line/SideShot/Inverse/Angle-Bearing Code <1>: 2
Enter Bearing Angle (dd.mmss) <58.1848>: 75.0627
Points/<Distance>: 553.69
N: 5053.85  E: 5553.28  Z: 0.00
Exit/Options/Arc/Points/Line/SideShot/Inverse/Angle-Bearing Code <2>: E (to exit)

6   Draw a Polyline from Point 1 to Point 2, and connect the segments with Join Nearest. We could have turned linework with traverse on before we got started, but now we will do it after-the-fact. So choose 2D Polyline under Draw. Some users like to simply type in 2DP at the command line that starts the Polyline command, also.

[Continue/Extend/Follow/Options/<Pick point or point numbers>]: 1
[Arc/Close/Distance/Follow/Undo/<Pick point or point numbers>]: 2
[Arc/Close/Distance/Extend/Follow/Line/Undo/<Pick point or point numbers>]: press Enter (to end)

Now we have two line objects. The first, from point 2 to point 3 is a pure Line. The second, from point 1 to point 2, is a true Polyline (even though it is only one segment long). It is officially a LWPOLYLINE, a lightweight polyline. This can be verified by picking it using the List command under Inquiry. Polylines are linked combinations of one or more line segments that behave as one unit. We encourage use of polylines versus lines because they offset as a unit, will take on a thickness or width, are easier to select and have superior editing capabilities. A line can be turned into a polyline by picking Polyedit under Edit, picking the line, and answering Y to the question "Do you want to turn it into one? <Y>". To join the polyline and line objects into a single polyline, choose the very useful command Join Nearest, found under Edit.

The defaults are good. Just click OK. Now pick the polyline from 1 to 2 and the line from 2 to 3, and then hit Enter for no more.

Now, see the grips on the new polyline by picking it with the cursor. See how the whole thing highlights? That is proof that it is joined up as a polyline.

7   Design a Curve with a 500’ Radius. Under Draw, pick Arc and slide over to 2 Tangents,Radius.

Radius of Arc <0.00>: 500
[nea] Pick Point on 1st Tangent Line: Pick on the 1st polyline segment closer to point 2
[nea] Pick Point on 2nd Tangent Line: Pick on the 2nd polyline segment close to point 2

The arc draws in, and the centerline remains a polyline, now with 3 segments.

8   I for Inverse. Entering I for Inverse, at the command line, is a handy way to get on a point to begin another traverse. Practice inversing. Enter I. Inverse from point 1, then to point 2, then to point 3 then back to 1. But you can also inverse (go to) a snapped position on a line or polyline, such as the midpoint of an arc. Let’s do that, because we want to traverse south from the midpoint of the arc. Enter I, for Inverse.

Calculate Bearing & Distance from starting point?
Traverse/SideShot/Options/Arc/Pick point or point number: MID (for midpoint snap) of Select the arc
Traverse/SideShot/Options/Arc/Pick point or point number: T (for traverse)
Traverse, Line ON, RAW FILE OFF
Exit/Options/Arc/Points/Line/SideShot/Inverse/Angle-Bearing Code <2>: press Enter
Enter Bearing Angle (dd.mmss) <75.0627>: 10.11
Calculated Bearing (Qdd.mmss): 210.1100
Points/<Distance>: 400
Exit/Options/Arc/Points/Line/SideShot/Inverse/Angle-Bearing Code <2>: E (to exit traverse)

Notice that you can transition from inverse, to traverse, to sideshot, etc. with these COGO options. We were in inverse, but we did T for traverse, and could have done I for inverse to return to inverse. This cuts down on keystrokes, and adds to the sense of fluidity of the software.

9   Turn a Line into a Polyline with Polyedit. The command Offsets & Intersections requires pure polylines, not lines, to execute. So, since we had Line On with the last traverse, we have created a line. To use this in street design, we need to convert it into a polyline. Select Polyedit under the Edit pulldown menu.

Select polyline or [Multiple]: Pick the side road line
Object selected is not a polyline
Do you want to turn it into one? <Y> press Enter
Enter an option [Close/Join/Width/Edit vertex/Fit/Spline/Decurve/Ltype gen/Undo]: press Enter

10  Offsets & Intersections. Under the Area/Layout menu, select Offsets & Intersections.

Select all PRIMARY road polylines.
Select objects: Enter (we will consider both these subdivision streets secondary)
Select all SECONDARY road polylines.
Select objects: Hold down the Shift key and pick the main centerline
Select objects: With shift key still down, pick the side road
Select objects: Enter (for no more)

The street intersections are presented in a dynamic dialog as shown above. Try experimenting with different radii under the Secondary Roads column, then clicking Calculate. The streets will re-draw in the upper graphical area. But after experimenting, change the four values under Secondary Roads to those shown (ignore Primary Roads -- those don’t apply here), and click Calculate. Then click Finish 2D. Note the drawn-out street intersection.

Now select Layer ID under the Inquiry menu. Pick on the outside polyline (it is layer ROW). Pick on the next polyline in from the outside (it is layer EOP). For example, if you had clicked off EOP under the Draw column in the above dialog, the edge-of-pavement polyline would not have drawn.

11  Standard Cul-de-Sac. Under Area/Layout, select Cul-de-Sacs. You may want to zoom into the area of the bottom center, near point 4. When finished with the procedure below, zoom back out.

Prompting:
Select all offset polylines to end with cul-de-sac.
Select objects: Do a crossing selection from right to left across the lower side road, selecting all 5 polylines (ROW-L, EOP-L, CL, EOP-R, ROW-R)
Select objects: press Enter (for no more)
Pick cul-de-sac center projection onto centerline: END (type end for endpoint snap)
Pick near the endpoint of the centerline of the lower side road near point 4. However make sure the pick is on the centerline polyline, or the routine will say the centerline not found.

This brings up the following dialog:

Again, you can change the Fillet Radius and the Outside Radius on the EOP or ROW, hit Calculate, and check out its effect. (Don’t make the Outside radii too small or it will fail Calculate if there is no workable solution). Set values as shown above. Then click on Finish 2D.

12  Teardrop Cul-de-Sac. Now select the Cul-de-Sacs routine again, under Area/Layout.

Select all offset polylines to end with cul-de-sac.
Select objects: Do a crossing selection pick from right to left across the right main road, selecting all 5 polylines (ROW-L, EOP-L, CL, EOP-R, ROW-R)
Select objects: Enter (for no more)
Pick cul-de-sac center projection onto centerline: END for endpoint snap Pick endpoint of the centerline of the lower side road near point 3

For a teardrop cul-de-sac, fill out the dialog as follows, then click on Calculate and Finish 2D.

Teardrop cul-de-sacs allow moving vans and other large vehicles more turning room, and have been popular in the Cincinnati area, for instance. Our drawing now appears as shown below, with the exception of the filled reference dots.

13  Let’s make a layer called LOTS using Layer Control found under View. It’s a good idea to create a layer and set it current before beginning the design process. Select Layer Control and obtain the following dialog:

Click on for New layer. When Layer1 highlights, as shown at bottom of list, type over it with LOTS, then click under the Color column and change the color to Magenta. Then click the (Set) Current button up top to make this layer current. Then click OK to exit the dialog.

Next, we will use Break at Selected Point, found in the Edit menu.

The Lot Layout routine under Area/Layout works nicely with reasonable polylines that run roughly parallel. Our goal is to make 1-acre lots. Lots of zigs, zags, and jogs in the polylines cause the perpendicular offset logic to fail to find a solution (lots will radiate perpendicular from the front polyline in Lot Layout). Not only should the front and back lines run opposite each other, but they should end at some point before the calculation runs into difficulty with impossible math.

The outer R-O-W polyline currently runs left-to-right, goes around both cul-de-sacs and returns right-to-left in one, connected polyline. We need to break it near where the filled dot is pointing. It should be easy to lay out lots along the upper portion of the subdivision, as long as we stop to break the R-O-W polyline before it turns and runs back through the lower, more complex frontage and back property portions.

Under Edit, select Break, and slide over to At Selected Point. You will select using the filled dots, shown on the plan above, as references.

Select Line, Arc, or Polyline at break point: Pick near the filled dot on the outer boundary polyline.
Repeat the command for the ROW polyline.
Select Line, Arc, or Polyline at break point: Pick the far right end of the Teardrop cul-de-sac R-O-W polyline.

To prove you have broken the polylines in two, click on the R-O-W polyline on the south side (only the south portion should highlight), then click on the north R-O-W polyline (which we will use as our frontage polyline in the command Lot Layout). Then press the ESC key twice, which gets rid of the grips, as does zooming or panning.

14  Select Lot Layout under Area/Layout. A dialog appears:

Fill out as shown. In particular, click off Apply Remainder Equally to All Lots (if it is on) so that we force 1.000 acres lots and don’t just get equal lots of some size such as 1.0017 (because the remainder lot that would not fit was added onto all lots).

Making Closed Polylines means that our side lines will be doubled up, each lot sharing a side line. Click OK.

Select front polyline: Pick north R-O-W
Select back polyline: Pick northernmost polyline the back property line.

The 1.00 acres lots are laid out as far as is possible. You may get a small lot at the end of the row, which you would erase.

15  Applications of Reverse Polyline. We can get one more lots from Lot Layout, by doing the lower R-O-W at the left side of the drawing, and picking the southern back polyline. Let’s try. Select Lot Layout under Area/Layout. Use same dialog entries. Select the front polyline as the southern edge of the road R-O-W, near the left side of the drawing. Select the back polyline as the southern property line. Oops! Nothing drew. It was unable to calculate. It turns out that the direction of the polyline is important. The southern R-O-W polyline starts way off to the right, so the program was not even considering where we were looking!  We need to reverse the direction of the southern R-O-W polyline so it starts on the left side. Select Reverse Polyline, found under the Edit pulldown, sliding over from Polyline Utilities. It prompts:

Select polyline or line to reverse: Pick the southern R-O-W polyline.

The polyline now reverses direction, goes left-to-right, and shows phantom direction lines (which are automatically removed when the command ends). Now repeat the Lot Layout command as outlined in the beginning of Step 15, and we get one new lot out of the exercise, as shown below. If you get a second wedge shaped lot, erase it.

16  Break at Intersection. The lower back property line is still continuous. We can work with it in small pieces rather than as one big polyline. Say we want to break it as the inside corner identified by the arrow above. To do this, select Edit pulldown, Break, sliding over to At Intersection. Prompting:

Select Line, Arc, or Polyline to Break: Pick the south property line
[app on] Pick Intersection to break at: Move the cursor to the intersection point indicated above, look for the INT snap to appear as you approach the exact corner (which is an intersect), then click there.

17  Draw a Polyline from the corner indicated by the filled dot to the beginning of the R-O-W arc, also indicated by a filled dot in the previous graphic. Select 2D Polyline under Draw.

Pick point or point numbers: End (type in end for the endpoint snap)
of ..Pick the inner back property corner
Undo/Arc/Length/<Pick point or point numbers>: End (type in end for the endpoint snap)
of ..Pick the beginning of the Arc (it will show endpt when you get close to the true start of arc)
Undo/+/-/Arc/Close/Length/<Pick point or point numbers>: Enter (to end)

18  Area by Interior Point. We have just created a new lot, but the lot is not defined by one, single, closed polyline. If we want to verify its area, however, we can still use the command Area by Interior Point. Select Area by Interior Point under Area.

Pick point inside area perimeter: Pick inside our new lot

SQ. FEET: 40997.2  SQ. YARDS: 4555.2  SQ. MILES: 0.0

ACRES: 0.9412  PERIMETER: 830.5026

Pick area label centering point: Press Enter here to avoid labeling.

The lot is less than one acres. We will set as a goal to extend its lower boundary to the right to obtain one acre. That is accomplished by using the command Hinged Area. But Hinged Area works best if we have a nice, closed polyline for the new lot. We can get one using the command Boundary Polyline.

19  Boundary Polyline. At the command line, type in BPOLY (or BOUNDARY). When the dialog appears, pick New.

Then pick all the polylines that surround our new lot. Then after you hit Enter to Select objects, this same dialog returns. Then you select Pick Points and pick inside the lot. This creates a new closed polyline, in the current, LOTS layer (magenta).

20  Select Hinged Area under the Area/Layout pulldown.

Define area by points or closed polyline [Points/<Linework>]? press Enter (for linework)
Select polyline segment to adjust: Pick on the right-side line
Select hinge point [endp]: Pick on the upper right hinge point (see arrow)
Keep existing polyline [Yes/<No>]? N
Area: 40997.20 S.F, 0.9412 Acres
Remainder/Acres/<Enter target area (s.f.)>: A (for acres)
Remainder/SF/<Enter target area (acres)>: 1.0

The new lot draws, as shown below:

21  Next, use the Erase command to remove the segment that is pointed to above with the text Click on This Side. 

22  Make 2 More Lots with Polyline command. Instead of using Draw, 2D Polyline, we will use the straight AutoCAD polyline command. At the command line, enter PL.

Specify start point: END (type in the endpoint snap)
of Pick the endpoint (which is the lower right corner of the new lot).
Current line-width is 0.00
Specify next point or [Arc/Halfwidth/Length/Undo/Width]: PER (type in the perpendicular snap)
to Pick on the R-O-W polyline to the right.
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: press Enter (to end)

Now for the second lot. Referring to the drawing below, repeat the PL command, and answer as follows:

Specify start point: NEA (enter the nearest snap)
of Pick on the property line anywhere near the circled point 1 (no need to be exact)
Current line-width is 0.00
Specify next point or [Arc/Halfwidth/Length/Undo/Width]: PER (type in the perpendicular snap, which when intersecting arcs means radial to the arc)
to Pick on the R-O-W polyline near circled point 2.
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: ENTER (to end)

The drawing appears below:

23  Issue the Break at Intersect command, and break the back property polyline and the cul-de-sac R-O-W polyline at the intersections with our newly drawn polyline from step 22. Repeat this command, and break the back property polyline at the filled dot to the right of the “Sliding Side Area” label below.

24  Repeat Lot Layout with the same entries as before. The front and back polylines to select are shown below, along with the results. This gives us 2 more usable lots.

Next, use the 2D Polyline command to generate a segment (above the “Sliding Side Area” label below) that runs from the ENDpoint of the corner to a point PERpendicular to the R-O-W line. Then use BPOLY to create a closed boundary inside it.

Erasing the original segment you placed is a little tricky since the newly formed polyline is on top. When two pieces of geometry lie on top of each other, Carlson will take the one created last. Issue the Erase command, then hold down the control key while picking the segment above the “Sliding Side Area” label. When the single segment highlights, press enter to erase it, leaving the boundary polyline.

25  Sliding Side Area. Because we have a small closed polyline, we can investigate another area command, the Sliding Side Area. As shown in the graphic above, we want to slide the north side of the last, smaller lot parallel to its current bearing such that the lot will contain 1.00 acres. Select Sliding Side Area under the Area/Layout pulldown.

Define area by points or closed polyline [Points/<Linework>]?  press ENTER
Select polyline segment to adjust: Pick the north side of the lot above (shown here containing the words Sliding Side Area)
Keep existing polyline [Yes/<No>]? press ENTER
Area: 20375.30 S.F, 0.4678 Acres
Remainder/Acres/<Enter target area (s.f.)>: A (a for acres)
Remainder/SF/<Enter target area (acres)>: 1.0

26  Complete the remaining Lots. Using the 2D Polyline command, under Draw, use endpoint snaps and perpendicular snaps (end and per) to draw the final 3 polylines, shown below marked 1, 2 and 3 for reference.

It may not be the most aesthetic subdivision, but we applied a lot of tools making it. But we’re not done. There’s some real automation ahead.

27  Create Points from Entities. We have designed a subdivision, in effect, without point numbers. This is the beauty of CAD. But we need to make point numbers in order to stakeout the subdivision. To do this, select Create Points from Entities, under COGO. The following dialog appears:

Set the starting point number to 5, verify the dialog as shown, and click OK. A second dialog, covering what entities to capture, appears next. Stick with the default settings and click OK.

When it asks, Select objects, type in All. Press Enter for no more selections, and Enter again. All the point numbers for stakeout are created.

28  Number the lots, clockwise from the upper left, using the command Sequential Numbers. Under Draw, select Sequential Numbers. This dialog appears:

Choose the circled text and click OK.

Set the text size (height) to 16 and the starting text value to 10, as shown. Then click OK.

Pick point at center of label or type Polylines to label: Pick near the center of the first upper left lot.
Pick point for label alignment: Press F8 for <Ortho on> Pick to the right.

Now pick near the center of all of the lots, going clockwise.

When done, and back to the command line, press F8 again to set Ortho off.

The resulting drawing, with point numbers, is shown below:

29  Lot File by Interior Text. Official lot files can be created whenever a lot number or name exists within a lot as the sole text (other text may be present but could be frozen). So we will play it safe and first freeze the point number layer. Before we do, take note of the point number assigned to the NW corner of Lot 10. In our case, it is point 64 (it may be different in your case, depending on how you selected the objects in the command Convert Entities to Points).

Under View, select Freeze Layer and pick on one of the point numbers. Now go to the Area/Layout pulldown, select Create Lots and slide over to select Lot File by Interior Text.

A dialog box will appear. Be sure that is says Block Name 1. Click OK.

Select lot lines, polylines and text.
Select objects: Pick the lots and the lot numbers

The Lot Files will be created. Before we look at the Lot Files, let’s finish up and do area annotation on the upper lots, by the command Area by Interior Point.

Note: If we had not made points at all lot corners, using Convert Entities to Points, the Lot File by Interior Text would make point numbers. This is the reason for the prompt: Starting point number. If points are found, no new ones are created. Lot files must have points at all the corners.

30  Area by Interior Point. Select Area Defaults, under Area/Layout, and cancel the square feet plot, leaving only the area plot to 3 decimal places. Set as shown below:

Now choose Area by Interior Point, under the Area/Layout pulldown menu, and pick inside Lots 10 through 16, as shown below:

31  Select Lot Manager, under Area/Layout, and the following Lot Editor dialog appears:

Pick on Lot 10 and click Report. This will lead to the Lot Report dialog box.

Be sure that your setting are as shown above, and then click Lot Report.

This dialog is typical of the many Carlson Standard Report Viewer dialogs, first introduced in Carlson CES. You can click on 1 or more lines, highlight them and hit the delete key on the keyboard, and these lines will delete. You can edit lines directly in the dialog. You can also save the report to disk with the Save icon shown above. To exit, click the Exit icon.

32  The Edit Current (lot) option within the Lot Editor dialog box can be used to describe a lot by different point numbers, or to assign a lot to a different block. This is explained here and shown below for reference purposes only.

Click Lot Manager under the Area/Layout pulldown menu. You will see the Lot Editor dialog as shown in Step 31. First, make sure that a .lot file is open. If it is not, open one. Then, under Selection, select a lot to edit. Click Edit Current. You will get this dialog. Note the graphic display in the lower half, which map the Points listed above.

33  Re-Drawing Lots after Editing Points. Let’s assume you actually changed the point numbers that define Lot 10. That would cause the lot to draw differently. Also, you could simply alter the coordinate values of a point in the current lot file. That would also cause the lot to draw differently. Let’s take the latter approach. Remember point 64?  It is the NW corner of lot 10 (in our case your’s may be different as stated above). So select Edit Points under the Points pulldown menu. A spreadsheet appears. Scroll down to point 64 (or whatever point is your NW corner of Lot 10).

Click on the Northing and edit it to 5050. This is for illustration purposes. In reality, you might be fine-tuning your subdivision design points. As long as the same points define the lots, you are, in effect, making a ready-made new drawing. Now select at the top of the dialog File, then Save and Exit.

34  Draw the Lot File. Before we draw the lot file, save your drawing by selecting Save under the File pulldown menu. Then choose New, exit the Startup Wizard (if it appears), and go straight to Lot Manager, found under the Area/Layout pulldown menu. Lot Manager provides the tools for drawing lot files to the screen.

Click the Existing tab. Select the plat4 lot file and click Open. Now select your existing crd file that you created earlier. In the next dialog, called Lot Editor, shown below, choose all lots by clicking Select All. Then click Draw.

Accept the defaults and click OK to the Draw Lots dialog box. This leads to the Auto-Annotate dialog, shown below. Use the settings shown here. Click OK.

Next comes the Area Defaults dialog, as seen in Step 30. Fill out exactly as shown in Step 30.