Dropped Kerb and Tactile Paving

This page covers the two commands that draw the pedestrian access at a corner: the dropped kerb and the tactile paving that goes with it.

What it does

Dropped kerb

You select the kerb (the kerb line) and mark the stretch to drop. From there the command assembles the drop:

• the stretch of kerb between the two points is offset into the footway by the grade length, and that offset line is the edge of the ramp next to the carriageway;
• the two end faces link that edge back to the perpendicular feet on the kerb;
• if there is a side transition, it is added at each end.

The ramp comes out on the side opposite the clicked point: click slightly to the carriageway side and it goes into the footway. Flip side (7) swaps it.

The grade length is computed on its own from the kerb height and the gradient: c = h × 100 / i. Typing the length runs the calculation the other way and recomputes the gradient. Above 8.33 % — the maximum gradient of the accessibility norm of the active country profile — the gradient box turns pink.

There is no accept button: closing the form is the accept. Whatever is drawn stays.

Tactile paving

You select the kerb and click two points on it: the two ends of the tactile field along the kerb. The studs are taken square to the kerb at the second point (the Angle box shows that direction and can be changed afterwards), the width is the distance between the two points, and from that frame the command draws the tactile grid at once. Everything is a 0.40 m grid; the figure is fixed, there is no field for it. The tiles count from the first point: when the width is not a multiple of 0.40 m the partial tile is the last one, at the far end, and the tail sits on the same grid.

The drawing has up to five parts: the body rows along the kerb, the body cross lines, the tail (the stem back across the footway) and, on a kerb that is not square to the studs, the two combs that fill the wedge between the body and the kerb. The style decides the layer and the guidance figures: Controlled (Red) sets 3 body rows (1200 mm), Uncontrolled (Buff) sets 2 (800 mm), and both set the stem to 2 columns (800 mm), as in the DfT Guidance on the Use of Tactile Paving Surfaces. Charcoal leaves the boxes as they are. The boxes stay editable: a typed value overrides the preset until the style changes.

The Standard group switches the rule. Brazil (NBR) draws the NBR 16537 arrangement instead: an alert strip along the kerb (one 0.40 m module deep, or two 0.25 m modules) and a directional strip one module wide, centred on the field, running back across the footway by the Tail rows; a Setback moves the alert strip away from the kerb to the ramp top. The standard follows the country profile and can be changed on the form.

Workflow

Dropped kerb

1. Run CAPCAD_ROAD_KERB_DROPPED.
2. Type the Curb H (11) and pick the Slope (12); the Grade length (9) is computed.
3. Choose the method: 1 point + length (2) or 2 points (1). In the first, fill in the Length (13).
4. Click Selecionar guia… ("select kerb…", 4) and pick the kerb and the point or points. The drop is drawn at once.
5. Adjust the side transition (21, 22, 25) and the skew (17), pressing Enter in each field.
6. To change the length along the kerb, type the Length (13), pick the anchor (14 to 16) and press Enter.
7. If the drop came out on the wrong side, click Flip side (7); to move it to the other side of the first point, along the kerb, Reverse direction (3).
8. Pick the Layer (28) and close the form.

Tactile paving

1. Run CAPCAD_ROAD_TACTILE.
2. Pick the style (50, 51, 52); Body rows and Tail columns follow the guidance.
3. Click Select (32), pick the kerb, then click point 1 and point 2 on it. The grid appears.
4. Adjust as needed: the Angle box (type a value, step it by 1° with the arrows, ∠ picks two points, / takes a line's direction, x goes back to the kerb + 90°), Flip side, Invert, the draw method (40 to 43) and the boxes (44 to 49). Every change redraws.
5. Reset (53) erases the drawing and keeps the selection, so the next change rebuilds it.

The form

The numbers on this page are unique: 1 to 30 on the Dropped Curb form and 31 to 60 on Tactiles. 61 and 62 are two controls of the Dropped Curb form that only show while there is a skew.

The Tactiles screenshots below were captured in a Portuguese session; the control numbering is the same in every language, and the tables quote the English captions. On the Dropped Curb form the main button (4) keeps a Portuguese caption, quoted here with a gloss.

The whole form. Units are metres unless stated otherwise.

With the skew (17) different from zero, the Swap pts button (61) and the ? (62) appear.

Tab 1: Ending — the crossing. The greyed-out controls are inert; see the table.

Tab 2: Path — three actions along a path, not available in this version.

Dropped kerb — selection

Dropped kerb — ramp

Dropped kerb — angles

Dropped kerb — side transition

Dropped kerb — footer

Tactile paving — Ending tab

The screenshot predates the 2026-10-31 revision. The numbers below refer to it where the control still exists; the input-method radios (35, 36), Invert beginning (33) and the old spinner (38) are gone, and the transitional-kerb controls (54, 56) moved to the Path tab.

Tactile paving — Path tab

How the options combine

The figures below came out of the engines themselves. The kerb is a straight line, the dropped stretch runs from 10 to 16 m, and the grade length is 1.20.

Side transition

Transition None: the ramp edge and the two end faces, and nothing else.

Transition Angular, angle 26.565°: a fan at each end, thrown to the kerb.

Transition Square, measurement 1.00: a step perpendicular to the kerb plus the run along it.

Tactile paving

The engine run over a sample frame: 3.20 m between the two points, 2.40 m deep, 2 body rows, 6 tail rows and 2 tail columns. Everything is a 0.40 m grid. The figure predates the 2026-10-31 revision: the tail there fans out; it now runs parallel, on the body's grid.

The same frame with Tail columns at zero: the whole tail disappears.

Remembered between sessions

Dropped kerb: selection method, transition type, transition measurement and angle, square-joint measurement, grade length, kerb height, length and gradient. The layer is saved under a key of its own. The transition measurement is saved, but recomputed on opening.

Tactile paving: nothing on the Ending tab; the form always opens on Controlled (Red) with the guidance figures. The transitional-kerb value is saved and survives between drawings.

Notes

• Closing the dropped-kerb form is the accept: only Reset erases the drawing.
• On a curved kerb spanning more than one segment, the ramp edge comes out as a straight chord between the two ends.
• When the angular transition does not meet the kerb, or when the square joint lands on a negative measurement, the drop comes out partial — and a warning appears in the form title and on the command line.
• The tactile combs are cast only at the stretch of kerb between the two points, so on an L-shaped kerb nothing reaches the other leg.