Curve Utilities — warning signs on horizontal curves

What it does

A signable curve is a horizontal curve tight enough to require a warning sign. The command walks the project alignment segment by segment and does three things:

1. Classifies every segment that has curvature. Two purely geometric quantities come out of each segment: the radius and the central angle (the deflection). With them the segment falls into sharp, signable or neither.
2. Groups neighbouring curves. A tangent between two curves shorter than the minimum tangent does not break the set: it is absorbed into the group. That is what turns two nearby reverse curves into an S curve and three or more into a winding stretch.
3. Emits the result — drawing the groups, inserting the signs, or inserting the delineators, according to the option ticked on the Curves tab.

What the alignment has to supply

The command works on the project alignment (the one defined by the Alignment Manager). No per-station property is needed: the classification is geometric, read from the polyline's bulges. Only Identify mode will work without a project alignment — it then asks you to pick one curve. Insert vertical signs and MAs require the project alignment and refuse to run without it.

The three modes

The layers Identify mode draws on, and their colours:

Workflow

1. Define the project alignment and run CAPCAD_ANALYTICS_CURVES. The form opens on the Curves tab, with the orange line Apenas projeto: <name> at the top when a project is active.
2. Check the Profile (28). It decides which set of classification criteria and which set of sign codes are used.
3. Go to the Parameters tab and check the radius and angle thresholds. Any of them can be edited, and Reset values to defaults (42) restores those of the selected profile.
4. Back on Curves, check the A2 central-angle method (19 or 20) — the two readings of criterion 2 give opposite answers, so this is the one setting worth looking at before every run.
5. Choose the mode (8, 12 or 23) and set PC offset (13), minimum tangent (17) and Alignment offset (15, 16).
6. Click Create (61). The form closes, the command runs, and the result is reported on the command line.
7. Running Identify first shows you the coloured groups on the plan, so you can tune the minimum tangent before letting the command insert anything.

The form

The numbers are the same in every figure on this page: 1 to 7 on the Eixo tab, 8 to 28 on Curves, 29 to 42 on Parameters, 43 to 60 on Signs, and 61 on the Create button, which sits outside the tabs and shows in every capture.

The screenshots are of a Portuguese session, and so are the labels inside the generated figures further down. The layout, the control numbering and the geometry are identical in an English session. The English captions of each control are the ones quoted in the tables.

The Curves tab, the form as it opens: the sign-insertion mode is already selected.

Tab 2: Curves

Mode

Sign siting

Groups

Alignment offset

A2 central-angle method

Criterion 2 of the normal signable curve exists in two conflicting readings, and the form makes you pick one. The two radios sit in the same group, so one of them is always selected.

Output and warnings

MAs

With MAs selected and none of the three type boxes ticked, Create refuses and stays open. On the second country profile the MAs mode is not available in this version and inserts nothing.

Profile

Tab 1: Eixo

The Eixo tab gathers four alignment-drawing utilities; two options are shown disabled. The tab caption and its controls are not translated.

These actions only run when no option on the Curves tab is selected — Curves takes precedence. All of them require the project alignment.

Tab 3: Parameters

The Parameters tab shows the two criteria with editable thresholds. The footnote line names the two manuals behind the two readings of criterion 2, untranslated.

The values below are the ones the form opens with. They are the thresholds of the first country profile; the second profile ignores this tab entirely (see Notes).

Sharp (A1)

Two bands, evaluated in sequence; either one makes the curve sharp.

Signable (A2)

Criterion 1 of the signable curve (35 to 38) has no effect in this version — see the note at the end of the page. In practice the signable class is decided entirely by criterion 2.

Tab 4: Signs

The Signs tab shows the sign codes of each catalogue. Every field is read-only: it is a lookup, not a setting.

Two of the twelve curve roles have no sign of their own in the first catalogue: the U-sharp-curve pair repeats the sharp-curve pair. The code tables themselves are Brazil-, Colombia- and Peru-specific and are listed on the Portuguese edition of this page.

How the options combine

What makes a curve signable

The criteria are two radius-and-angle bands for the sharp class and, in practice, one band for the signable class. The switch in 19/20 flips the angle test of that band, and the two readings are near-complements of each other: with the default thresholds, a curve of radius 200 m deflecting 60° is signable under the ≥ 45° reading and not under ≤ 45°; one of radius 200 m deflecting 20° is signable under ≤ 45° and not under ≥ 45°. Same curve, opposite answer — which is why the method is worth checking before every run.

Segments 10 m long or shorter never classify as a curve, however tight: the command treats them as straight.

The criteria maps that show this on the Portuguese page are labelled with the two bodies' names and with the sign codes, so they are not reproduced here.

From classification to groups

One sample alignment at three values of the minimum tangent, from a real run of the command. At 0 m no tangent is absorbed and the six curves become six independent groups — each would get its own sign. At 60 m they collapse into three groups. At 320 m the 300 m tangents are absorbed too and the whole stretch becomes a single group.

The last group of an alignment behaves differently: a group is only closed when a non-signable segment appears after it. An alignment that ends on a signable curve does not emit that last group. See the note at the end of the page.

Which sign each group gets

The choice comes from the number of curves in the group and the sense of each deflection. The codes come from the sign catalogue of the active country profile; the roles are these:

Each group receives two signs: the up-station one at PC offset metres before the group's PC, and the down-station one the same distance after its PT. Every sign of one run receives the same group identifier, so CAPCAD_SELECT_GROUP can reselect them later. The sign action is always install, and it is the action that decides the layer.

The figure of the classified alignment and the figure showing where the signs land are labelled with the sign codes of the Brazilian catalogue, so they are not reproduced here.

Remembered between sessions

Nothing. The form is built from scratch on every run and discarded at the end: every value returns to its default (mode Insert vertical signs, PC offset 30, minimum tangent 60, offset 8 with Detect on, the ≥ 45° A2 method, the first country profile).

The one exception is the MA options (27), which are kept for as long as the CAD stays open — they are the same ones CAPCAD_MA uses, shared by both.

Notes

• Criterion 1 of the signable curve (35 to 38) has no effect in this version. The signable class comes entirely from criterion 2; the four fields stay editable and have no effect.
• One A2 method is always selected. The two radios (19, 20) share one group box; the default is the ≥ 45° reading, and it is applied silently if you never look at the tab.
• The three layer buttons (9, 10, 11) do not act on the layers this command creates. They filter on ALIGNMENT_CURVAS_SINALIZAVEIS_VELO_, ALIGNMENT_CURVAS_ACENTUADAS_VELO_ and TANGENTE_MINIMA_, while Identify mode draws on CAPCAD_CURVA_ACENTUADA, CAPCAD_CURVA_SINALIZAVEL, CAPCAD_CURVA_U and CAPCAD_CURVA_TANGENTE. In practice the buttons only find layers from earlier analyses; to erase what this command drew, use the layers above directly.
• An alignment ending on a signable curve loses its last group. Grouping only closes a group when it meets a non-signable segment after it; if the alignment's final curve is signable, it is not emitted. Extend the alignment with a tangent, or handle that curve by hand.
• The second country profile's criteria are fixed. Its classification radius and angle thresholds are fixed (40 m / 30°, 80 m / 45°, 40–300 m and 80–300 m) and are not the ones on the Parameters tab, which stay those of the first profile. Only the U curve uses a configurable value (120°), and that field is not on the form.
• The Signs tab is a lookup only. The Culture list (43) is independent of the Profile (28) and offers one country more than Profile does: you can read a third catalogue's codes, but the command only knows how to insert the two the Profile offers.
• Several captions are untranslated. The Eixo tab and its controls, the Signs tab, the Layers esquem. label with its on/off/del buttons, the two A2-method radios and the Parameters footnote show their original text in an English session.
• For the sight-distance analysis of the same curves — where the curve hides the road ahead and overtaking has to be prohibited — see Overtaking sight distance and critical grades.