Where the side slopes meet the ground¶
What the program works out: at each chainage, where a design's side slopes meet the series it extends to (usually the ground, NSL): the left and right toes. The toes close the section, so they decide the width of the earthwork and its area (see Cross-section areas).
A design gets its side slopes from one of two places:
- The section settings, for a design laid from a point list or brought in as levels: the side slope set used at that chainage.
- The template itself, for a template made in the Template Designer: its own embankment (fill) and cutting slopes, and its berms.
Slopes are written 1 V : H¶
A slope is the horizontal run for 1 m of height: 2 means 1 V : 2 H. Where the section settings ask for a slope, two words are allowed as well:
- Ver: a vertical side. The toe is straight below or above the end of the design.
- Hor: a level side. The toe is at the level of the end of the design.
Side slopes from the section settings¶
Section Settings › Side slopes keeps named sets. Each set has a Left slope (1 V : H) and a Right slope (1 V : H) for every design series. On the Series page, each series has Extend to (what its slopes run to) and Default slopes (the set it uses at every chainage). To use another set at one chainage, or from one chainage on, pick it under Slope in the Side slope section of the section view's Quantities panel, with Apply to: This section, Each section I go to, From here to the end… or Every section…. The NSL has no side slopes.
One slope is given for each side, and it is used both ways: down from an end above the ground, up from an end below it.
How the toe is found, on each side:
- Start at the outermost point of the design on that side: the point with the smallest offset for the left toe, the largest for the right.
- From that point draw the slope line outward, both upward and downward: for every 1 m up or down, it goes the slope's run out.
- Walk the ground outward from that point, one piece (between two ground points) at a time. The first piece the slope line crosses gives the toe: the crossing point.
- The toe's offset is rounded to 3 decimals. Then the toe's offset and level are rounded as Precision (Offsets, Levels) on the Drawing page of Section Settings says. As entered leaves them as they are. 3 rounds the last decimal to 0 or 5: 75.743 becomes 75.745.
The toe is added to the series' line and to the ground's line.
When the slope never meets the ground. If the slope line crosses no piece of the surveyed ground (the ground stops short), the program runs the outermost piece of ground on, in a straight line, and the toe is where the slope line meets it. Tick Extend the ground (NSL) to the toe of the side slopes in Section Settings to draw the ground on to such a toe.
Side slopes of a Template Designer template¶
A template made in the Template Designer meets the ground by its own rules. At each end of its fixed part:
- The end is above the ground there: the side is in fill. It runs down at the template's fill slope (Embankment slope on a road, Fill slope on a custom template) to a Toe.
- The end is below the ground: the side is in cut. It runs up at its Cutting slope (or Cut slope) to a Top.
- The end is on the ground: no side slope.
So a template can be in fill on one side and in cut on the other, each at its own slope.
Berms by height. With Every … of height and Berm width (0 = none) set, a level berm of that width comes after each that height of slope, and the slope goes on from the berm's outer edge. If the ground is met on a berm, the toe is there.
When the slope never meets the ground. The program gives up after 80 m of height without berms, or 25 berms with them. Check Data then warns: The left (or right) side slope of the template "…" does not reach the ground here. The section carries on from its end with the side slope in the section settings. Change the template's side slopes or berms, or the design level of the row.
While the template's outer points lie on the ground, allowing for the rounding of Precision, they are the toes. The side slopes in the section settings are not used.
When the ground is edited after the sections were built. The template's outer points are then off the ground. The program works the template out again on the ground as it is now, so its own side slopes run to the new ground, but only while the series' centre point is still where the template puts it (at the design level of the row). The new points go into the section's points table, and the section shows as changed until you save.
If you moved the design up or down (for example with Adjust to Target, see Reach a target area), its centre point is no longer the template's. Its points are kept as they are, and the toes are found with the side slopes in the section settings, as above.
Worked example¶
The road from Cross-section areas. The ground is level at R.L. 100.000 left of the centre line and rises 1 in 4 to the right: ground (-10, 100.000), (0, 100.000), (10, 102.500). The formation runs from offset -4 to 4 at R.L. 100.500. The side slope set gives 2 (1 V : 2 H) on both sides.
Left toe. The left end is (-4, 100.500). The ground there is 100.000, so the end is 0.500 above it and the slope runs down. After going down a height h:
offset = −4 − 2 h, level = 100.500 − h
The ground on that side is level at 100.000, so 100.500 − h = 100.000, and h = 0.500.
offset = −4 − 2 × 0.500 = −5.000, level = 100.000
Left toe: (-5.000, 100.000).
Right toe. The right end is (4, 100.500). The ground there is 100.000 + 0.25 × 4 = 101.000, so the end is 0.500 below it and the slope runs up. After going up a height h:
offset = 4 + 2 h, level = 100.500 + h
The ground there is 100.000 + 0.25 × offset = 100.000 + 0.25 × (4 + 2 h) = 101.000 + 0.5 h. So 100.500 + h = 101.000 + 0.5 h, and h = 1.000.
offset = 4 + 2 × 1.000 = 6.000, level = 101.500
Right toe: (6.000, 101.500). The ground at offset 6 is 100.000 + 0.25 × 6 = 101.500, the same.
Both toes end in 0 at 3 decimals, so Precision 3 leaves them as they are.
If the ground stopped short. Had the ground been surveyed only to offset 5 (R.L. 101.250), the right slope would cross no piece of it. The program runs the last piece, from (0, 100.000) to (5, 101.250), on in a straight line, and the toe is the same: (6.000, 101.500).
As a template. A Template Designer template with this formation, a fill slope of 2 and a cutting slope of 2 would end on the same toes: the left side in fill (a Toe), the right side in cut (a Top).