Edit alignment geometry

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First, I'll show you some of the ways we can edit an alignment using grips.

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If you pick an alignment on screen, you'll see grips appear

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similar to the grips. You see when you edit a polyline,

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the square grip on the end of a tangent

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allows you to move the end of the tangent changing its direction and length.

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The square grip in the middle of a tangent

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allows you to move the tangent retaining its length

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and moving it parallel to itself.

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Circle grips at the end of a curve

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allow you to change the length and radius of the curve.

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The circle grip in the center of the curve

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allows you to move the curve to go through a pasty point,

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changing its length and radius.

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The arrow grip on the curve also allows you

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to change the length and radius of the curve

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moving it towards or away from the intersection point.

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The triangle grip at the intersection point

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allows you to move the intersection point,

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changing the direction and length of the tangents.

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But keeping the curve radius fixed

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when you move the intersection point, adjacent curves may meet each other,

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preventing any further movement

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you may need to adjust the length of any attached curves to

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be able to move the IP to where you need it.

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You can also use the triangle grip at the intersection point to break the IP apart.

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When you break it apart,

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you get two new grips at the end of

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each tangent and you can move each tangent independently.

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First, let's have a look at editing the sycamore heights alignment.

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We can see that our applied design checks

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have resulted in some warnings being placed on the alignment.

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These are indicating that the curve radii

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are currently too small to meet our design standards.

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We're going to edit the alignment to fix the radii

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and make improvements to the alignment.

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Select the alignment to call up the grips.

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We can use the curved rips to drag the first curve out to increase its radius. A

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small adjustment should be enough to remove the warning

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at the intersection with our collector road. You can see that the tangent

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is joining it at a slight angle.

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And ideally, we would like it to be near perpendicular.

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Click on the first intersection point and use the triangle grip,

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drag it out,

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improving the angle of the first tangent to mcallister boulevard.

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Now adjust the last curve on the alignment

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by dragging the curve out so that the end

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of the curve just extends beyond woodside view,

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looking at the entire alignment. It is clear we could simplify the geometry

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by removing the central curve

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and instead have a single curve across the top of the road.

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Using the alignment layout tools,

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we can delete these elements on the road

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and we can place a new curve between them.

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It will need to be a free curve because it

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will be attached at both ends to another entity.

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We'll use the option free cur filet with the radius,

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pick the incoming, then the outgoing tangent,

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the curve angle will be less than 180

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and then type in a curve radius of 600.

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We can see now that we've created another problem

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as a tangent length here is too short.

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It needs to be a minimum length of 100 ft.

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Instead of editing this on screen, we'll open the alignment grid view

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in here. We can see the geometry of the alignment in table form

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any property in here. That's not grayed out can be edited.

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We can edit the tang

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he constraints,

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the curved radii

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change the chord length or the degree of curvature,

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set the radius of the first curve to 400 ft.

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You can see that now we have improved the length of the tangent

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and all of the warning markers have gone.

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Let's see what happens if we change the tangy constraint.

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This curve is currently constrained on both sides. It's a free curve,

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we can change its constraint to a fixed curve.

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And now you can see you can no longer edit the radius because it is now fixed.

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If we edit this graphically and move the curve using its grip,

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the curve retains its radius but the tangents move

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because the tangents are now floating entities.

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If we rec constrain the curve back to a free curve,

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notice how the tangents are now fixed tangents again.

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Now we'll let it our collector road mcallister Boulevard.

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We can see on this part of the alignment here that we have three warning markers.

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This marker indicates that it doesn't meet our minimum radius of 1500 ft.

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This is from the design criteria file

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and it doesn't meet our local standard of a minimum radius of 1200 ft,

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which was added through our check set.

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Similarly,

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this curve has the same problem.

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This tangent is too short.

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It stands to reason that if we make these curves longer by increasing the radius,

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then we will reduce the length of the tangent

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making that situation worse.

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This geometry isn't going to work. So we need to redefine this part of the alignment,

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select the alignment and open the alignment layout tools.

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We will delete the geometry on this part of the alignment.

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First delete the tangent.

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And then this curve,

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we can now place a new curve between the existing curve and the existing tangent.

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It will need to be a free curve.

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So we'll use a free curve filet between two entities with the radius,

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pick the curve going in and the tangent going out

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on the command line. It's asking you if this is a compound curve or reverse curve

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type R for a reverse curve because it's turning

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in the opposite direction to the first curve set,

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the radius to the default of 1500

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we still have to fix the radius on this curve.

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So let's call up the alignment grid view.

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And in here, we'll change the curve radius for the curve to 1500.

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We've now fixed all of the geometry issues on the collector road,

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adjust the woodside view alignment so that the start and end of the

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alignments are snapped on to the new position of the alignments we've changed.

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Finally, there's one last edit that we need to make

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a Callister boulevard alignment has its station zero

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at the start of the alignment

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some distance along the existing road.

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We want to have station zero at the end of the existing part of the road,

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but we don't want to shorten the alignment

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as the starting segment helps us to establish the levels we'll need to tie into.

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We can use the alignment properties to reset the position of station zero

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on the station control tab, select the button beside the co ordinate values.

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This will allow us to pick a new coordinate reference for station zero.

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The warning message tells us that changing the stationing

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might affect other objects that have already been created.

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We don't need to worry about that. So click. OK.

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Snap to the end of the red center line on

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the survey drawing for the position of station zero.

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Click OK.

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To accept the changes

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in the drawing, you can see we have reset the station zero marker

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and the station values before this are negative.

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We've now completed our edits of the alignments in the drawing

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and we can move on to design our vertical geometry.