.. index::
   single: Assemblies and Corridors
   single: Assemblies
   single: Corridors

Assemblies and Corridors
========================

The corridor system turns an alignment plus a parametric cross-section
("assembly") plus a ground surface into a 3D road model with cut/fill
volumes, top and datum surfaces, and feature lines.

Overview
--------

An **assembly** is a named cross-section template containing left and
right rows of pre-built road elements: lanes, shoulders, curbs,
sidewalks, medians, slopes.  Each drawing has its own *Assembly
Library*, accessed via **Civil › Assemblies…**.

A **corridor** is a binding between one alignment, one target surface
(an existing-ground TIN), and one assembly.  The **Build Corridor**
command evaluates the assembly along the alignment and produces 3D
outputs in the drawing.

You need three things to build a corridor:

1. An **alignment** with horizontal geometry and a vertical profile.
2. A **target surface** (TIN) representing the existing ground.
3. An **assembly** describing the cross-section.

.. figure:: ../../../images/assembly_concept.png
   :align: center

   Three inputs (alignment, assembly, target TIN) combine into a
   single corridor entity that produces six output artifacts.

.. index::
   single: Assembly elements

Assembly elements
-----------------

Seven row types cover the building blocks of a typical road
cross-section.  Rows are added in order from the centerline outward
on each side via the row-palette buttons in the Assembly Editor.

.. index::
   single: Lane

Lane
~~~~

A drivable carriageway segment.  Parameterised by width, cross-slope
(superelevation-aware), and pavement depth.  The pavement depth
drives the datum surface — what sits under the road.

.. figure:: ../../../images/element_lane.png
   :align: center

   Lane element schematic.

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **Width**
     - Lane width in metres, measured from the parent point outward.
   * - **CrossSlope**
     - Signed cross-slope as a decimal fraction.  Negative means
       falling away from CL.  Receives the alignment's superelevation
       when ``Peraltable=True``.
   * - **PaveDepth**
     - (v1 legacy — migrated to a single course on load; use
       **Courses…**) Vertical pavement thickness in metres.  In the
       current model the pavement is a **course stack** — see
       "Pavement structure — courses and materials" below.
   * - **Peraltable**
     - When True, the cross-slope is overridden by the alignment's
       SuperelevationLeft / SuperelevationRight value at each station.

**When to use it.** Every road has at least one lane per direction.
For divided roads, combine with a Median element between the
opposing directions.

.. index::
   single: Shoulder

Shoulder
~~~~~~~~

A narrower paved strip outboard of the outermost lane, typically
sloped more steeply away from CL to shed water.  Mechanically a
narrower Lane with its own layer and label, named differently so
quantities and feature lines distinguish it from the carriageway.

.. figure:: ../../../images/element_shoulder.png
   :align: center

   Shoulder element schematic (with parent Lane).

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **Width**
     - Shoulder width in metres.  Typical 0.5–2.5 m depending on road class.
   * - **CrossSlope**
     - Signed cross-slope, typically steeper than the lane (e.g. −3%).
   * - **PaveDepth**
     - (v1 legacy — migrated to a single course on load; use
       **Courses…**) Pavement thickness, usually thinner than the lane
       (e.g. 0.05 m).
   * - **Peraltable**
     - When True, follows the alignment's superelevation.

**When to use it.** Rural and highway designs almost always have
shoulders.  Urban designs typically use a Curb + Sidewalk instead.

.. index::
   single: Median

Median
~~~~~~

A divider strip at the centerline of a divided road, typically
depressed below the running surface for drainage.  Sits at the
pivot.

.. figure:: ../../../images/element_median.png
   :align: center

   Median element schematic.

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **HalfWidth**
     - Half the total median width in metres (the full median is
       2 × HalfWidth across both sides).
   * - **Depth**
     - Vertical depression below the lane level in metres.
   * - **InnerSlope**
     - Slope of the inner face of the median (V/H).

**When to use it.** Divided highways and urban boulevards.  Place
the Median as the first row on each side so the lanes that follow
sit on its outer edge.

.. index::
   single: Curb

Curb
~~~~

An urban kerb — a stepped concrete profile separating the
carriageway from the sidewalk.  Three points define the profile:
foot (at lane edge), top (raised), back (where the sidewalk begins).

.. figure:: ../../../images/element_curb.png
   :align: center

   Curb element schematic (with parent Lane).

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **FaceW**
     - Horizontal width of the curb face in metres (typically 0.02–0.10 m).
   * - **FaceH**
     - Vertical face height in metres (typically 0.10–0.20 m).
   * - **TopW**
     - Top width in metres (the flat top of the kerb stone).

**When to use it.** Urban streets with sidewalks.  Combine with a
Sidewalk row immediately after the Curb.

.. index::
   single: Sidewalk

Sidewalk
~~~~~~~~

A pedestrian walking surface outboard of the curb.  Mechanically
similar to a Lane (width + cross-slope + depth) but typically with
gentler slopes and shallower pavement.

.. figure:: ../../../images/element_sidewalk.png
   :align: center

   Sidewalk element schematic (with parent Lane + Curb).

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **Width**
     - Sidewalk width in metres.  Typical 1.0–3.0 m.
   * - **CrossSlope**
     - Drainage slope, typically gentle (e.g. −2%).
   * - **PaveDepth**
     - (v1 legacy — migrated to a single course on load; use
       **Courses…**) Pavement thickness, typically shallow
       (e.g. 0.05 m).

**When to use it.** Urban roads with pedestrian provision.  Always
follows a Curb.

.. index::
   single: Slope

Slope
~~~~~

The daylight chain — connects the outermost designed point to the
existing-ground TIN.  Walks at the cut slope until the TIN is
reached if the design is above ground; walks at the fill slope
if below ground.

.. figure:: ../../../images/element_slope.png
   :align: center

   Slope element schematic showing cut and fill daylighting.

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **CutSlope**
     - Vertical-to-horizontal ratio for cut sections (design above ground).
       E.g. ``0.6667`` = 1V:1.5H, the typical default.  Steeper for rock,
       gentler for soft soils.
   * - **FillSlope**
     - Vertical-to-horizontal ratio for fill sections (design below ground).
       E.g. ``0.5`` = 1V:2H.  Typically gentler than cut slopes.

**When to use it.** The last element on each side of every
assembly.  Without it the corridor has no defined edge to the
existing-ground.

.. index::
   single: Generic

Generic
~~~~~~~

An escape hatch for cross-section elements not covered by the
catalogue.  Specifies a raw (DX, DY) offset from the parent point.
No automatic relationship to lanes, layers, or superelevation —
exactly what you type is exactly what you get.

.. figure:: ../../../images/element_generic.png
   :align: center

   Generic element schematic — raw DX/DY offset.

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **DX**
     - Horizontal offset in metres from the parent point.  Sign is
       absolute (not flipped by side), so author Left- and Right-
       side Generic rows with opposing signs if you want symmetry.
   * - **DY**
     - Vertical offset in metres from the parent point.

**When to use it.** Crash barriers, retaining walls, custom
guardrails, ditches that don't fit the Slope template, or any
geometry the Lane/Shoulder/Curb/Median/Sidewalk vocabulary
doesn't capture.

.. index::
   single: Pavement structure
   single: Courses
   single: Materials (assembly)

Pavement structure — courses and materials
-------------------------------------------

Lane, Shoulder, and Sidewalk rows no longer carry a single pavement
thickness.  Each carries a **course stack**: an ordered list of
courses, where each course is a parametric shape (material + width +
thickness + edge treatment) anchored to an earlier point in the
assembly.

What a course is
~~~~~~~~~~~~~~~~~

A course has:

- **Material** — a name from the drawing's material library (below).
- **Width** / **Thickness** — in metres; a Width of 0 inherits the
  parent row's width.
- **Edge treatment** (left and right independently) — **Vertical**
  (a plain rectangular edge) or **Taper** with a slope (dh/dv), which
  widens the course's bottom edge outward, producing a benched or
  stepped course boundary.
- **Anchor** — a 9-point attachment: **SelfPt** (the course's own
  corner) glued to **TargetPt** (a named point of an earlier
  structure), plus a **DX/DY** offset.  The nine anchor points are
  the corners and edge midpoints of the course's rectangle: ``TL /
  TC / TR / ML / MC / MR / BL / BC / BR`` (top/middle/bottom ×
  left/centre/right).

Chain default
~~~~~~~~~~~~~

Leave **Target** blank and a course anchors to the chain default:
the first course (index 0) hangs from the row's top link (``TL``);
course *k* hangs under course *k* − 1's bottom-left corner
(``TL → BL``).  This is exactly the historical single-PaveDepth
behaviour — templates only need explicit anchors where they deviate
from a straight-down stack.

Wider / centered courses
~~~~~~~~~~~~~~~~~~~~~~~~~

A base or subbase course usually needs to be wider than the layer
above it.  To centre the extra width on both sides, set **SelfPt =
TC** and **TargetPt = BC** (top-centre onto bottom-centre) together
with a **Width** greater than the row width: the course centres
itself under the course above and steps out evenly on both sides.
The shipped Base course instead widens *outward only* (see below):
it keeps the default anchor, so its inner edge stays pinned directly
under the course above (and ultimately under the row's own inner
anchor) while the full extra width goes on the outer edge
(``width = W + 0.6``).

Taper feet
~~~~~~~~~~

Set an edge to **Taper** with a slope to get a widening foot instead
of a vertical step — typical for a subbase course that needs to bear
on undisturbed ground beyond the layers above it.  The shipped
Subbase course uses **Taper 1:1** on its outer edge only — the inner
edge stays vertical, pinned at the row's own inner anchor — with
``width = W + 1.2``.

Cross-row anchoring
~~~~~~~~~~~~~~~~~~~~

A course's **Target** field can name another row's structure, not
just "the course above" — e.g. a drainage course anchored to
``LaneL.Subbase.BR`` ties its self point to the bottom-right corner
of the left lane's subbase course, letting one row's stack key off
another row's.  Anchoring to a structure that hasn't been built yet
(a forward reference, or a cycle) fails the build with a console
error naming the unresolved target instead of crashing — fix the
name and rebuild.

Drawing-level material library
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Every drawing has its own material library (independent of the
assembly library), opened with the **Materials…** button in the
Assembly Editor header.  It comes seeded with seven defaults:

- Asphalt Wearing
- Asphalt Binder
- Asphalt Base
- Base (crushed stone)
- Subbase
- Concrete
- Drainage gravel

Each material is a name plus a display colour; add, delete, or
recolour entries freely, and reference any of them from any course's
**Material** field.

The datum: bottom of the last course
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The corridor's datum surface follows the **outer bottom corners of a
row's LAST course** — not whichever course happens to be
geometrically deepest.  Because custom anchors (cross-row targets,
DX/DY offsets) mean the true deepest bottom isn't knowable until the
whole stack resolves, the rule is simply "the deepest course goes
last"; every shipped template already follows it (subbase is always
the final course).  Curb, Median, and Generic rows still advance the
datum chain the way they always did (to their Back / Edge / offset
point).  A row with **no courses** (a "zero-course" row — see below)
advances the datum from its own top link only.

Quantities: per-material volumes + excavation-to-formation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``BUILDCORRIDOR`` now prints, after the usual cut/fill/net line:

- **Excavation (to formation)** — the volume between existing ground
  and the datum surface where ground sits above datum, i.e. what
  actually has to be dug to reach subgrade.  This is distinct from
  the ground-vs-top cut/fill figure, which ignores everything below
  the finished road surface.
- A **material table**, one row per material referenced anywhere in
  the assembly, each the integrated volume of every course tagged
  with that material along the whole corridor.

Known v1 simplifications
~~~~~~~~~~~~~~~~~~~~~~~~~

Two shortcuts are accepted in this phase and may be refined later.
(The 2026-07-22 final review corrected both this section and the
shipped templates themselves — see below; the previously-published
"roughly 0.075 m²" figure was wrong on top of describing the wrong
joint, by about 8x.)

- **CL/median joint — none.**  Base and Subbase widen *outward only*
  from each row's own inner anchor (never back past CL or a median
  edge), so on a single-lane side (Rural, Rural-Narrow, Urban) the two
  lanes' courses meet exactly at the shared edge with **zero**
  overlap.
- **Adjacent-lane stack overlap (multi-lane sides only).**  On a
  multi-lane side (Urban-Boulevard, Highway, Freeway) each lane's
  Base/Subbase still widens outward past its *own* outer edge into
  the footprint of the *next* lane, whose own courses start fresh
  from its own inner edge and never reach back — so the same kind of
  double count still happens, just at the internal lane-to-lane joint
  instead of at CL. For the shipped stacks: Base overlaps
  0.6 m × 0.25 m = 0.15 m², Subbase overlaps 1.5 m (1.2 m rectangle +
  0.3 m taper foot) × 0.30 m = 0.45 m², roughly **0.6 m² of
  cross-section per internal lane-to-lane joint** (every shipped
  multi-lane template's lane width exceeds the 1.5 m Subbase reach, so
  this figure is exact, not capped by a narrower neighbour).
- **Shoulder interface.**  The same outward reach also overlaps a
  Lane's own following Shoulder — capped by the shoulder's width where
  that is narrower than the 0.6 m/1.5 m reach (e.g. Rural-2x3.5's
  1.0 m-wide shoulder caps the Subbase overlap at 1.0 m × 0.30 m =
  0.30 m² rather than the full 0.45 m²) — on top of the pre-existing
  small thickness step where the shoulder's own Wearing course meets
  the lane's Binder course rather than tying in continuously. A fully
  continuous tie-in is possible today via cross-row anchors but the
  shipped templates don't yet author it — planned template work for a
  later phase.

Zero-course rows
~~~~~~~~~~~~~~~~~

A pavement row (lane/shoulder/sidewalk) with an empty course array is
a legal "zero-course" row: for datum purposes it behaves like a bare
top-only row — only its top link is emitted, no separate datum point
is paired to it, and the next row's stack continues from that top
link exactly as before courses existed.  This is also the shape a
lane/shoulder/sidewalk row takes if you delete every row in its
**Courses…** dialog.

.. index::
   single: Section styles
   single: Corridor section style library
   single: Section View Styles

Section styles
---------------

Corridor cross-sections — both model-space section views
(``TAECC_SECTIONVIEW``) and the section sheets generated for plotting
(``TAECC_SECTIONSHEET``) — draw their appearance from a named
**corridor section style**.  A style is a single named record that
controls material fills (solid colour or hatch), per-element outline
colours, the corridor silhouette pen, the background/grid, cut/fill
shading, and four independent annotation toggles.  Styles live in a
library on the drawing, exactly like the alignment, surface, and
profile-view style libraries; a view or sheet picks one by name, and a
blank name — or a name that no longer exists in the library — falls
back to **Standard**.

Geometry (extents, datum/top elevation, vertical exaggeration, title)
stays on the view/sheet itself; the style only ever controls how that
geometry is *drawn*.

Built-in styles
~~~~~~~~~~~~~~~

Every drawing's corridor section style library ships with two
built-in styles that cannot be renamed or deleted:

.. list-table::
   :header-rows: 1
   :widths: 20 80

   * - Style
     - Description
   * - **Standard**
     - Solid material fills using each material's colour from the
       drawing's material library (the same colours seen in the
       Assembly Editor preview), grey course outlines, and a yellow
       dash-dot corridor silhouette.
   * - **Monochrome**
     - Plot-ready: white background, black pens throughout (grid,
       ground, outlines, silhouette), cut/fill shading turned off, and
       all seven default materials filled with a black **ANSI31**
       hatch (alternating 0°/90° angle material-to-material) instead
       of a solid colour.

Both built-ins, and any custom style you add, are available to every
section view and sheet in the drawing.

.. index::
   single: Opening the Section Style Editor

Opening the Style Editor
~~~~~~~~~~~~~~~~~~~~~~~~~

**Civil › Style Manager**, then select **Section View Styles** in the
left-hand category tree.  The editor embeds in the manager's right
pane: a left list strip of every style in the library — **New**,
**Duplicate**, **Rename**, **Delete** buttons below it (**Standard**
is protected from rename and delete) — and a tabbed panel on the right
with five tabs: **View**, **Ground**, **Corridor**, **Annotations**,
**Preview**.

.. index::
   single: Section style editable fields

Editable fields
~~~~~~~~~~~~~~~~

.. list-table:: View tab
   :header-rows: 1
   :widths: 25 75

   * - Field
     - Meaning
   * - Show grid
     - Toggles the background grid.
   * - Background / grid / minor-grid colour
     - Colours for the view background and the major/minor grid lines.
   * - Major/minor grid X/Y
     - Grid line spacing, horizontal and vertical, in drawing units.
   * - Axis text height
     - Pixel height of the offset/elevation axis labels.

.. list-table:: Ground tab
   :header-rows: 1
   :widths: 25 75

   * - Field
     - Meaning
   * - Ground pen colour / width
     - Pen for the existing-ground surface polyline(s).
   * - Show cut/fill shading
     - Toggles the tinted region between existing ground and the
       corridor's top surface.
   * - Cut colour / Fill colour
     - Shading colours for the cut region (ground above design) and
       the fill region (ground below design).

.. list-table:: Corridor tab
   :header-rows: 1
   :widths: 25 75

   * - Field
     - Meaning
   * - Show material fills
     - Master toggle for every course-shape fill (solid or hatch).
   * - Overrides grid
     - Per-material fill overrides — see "Material fills and
       overrides" below.
   * - Outline colours (7)
     - One colour per row kind — **Lane, Shoulder, Median, Curb,
       Sidewalk, Slope, Generic** — for the course-shape outlines of
       that kind.
   * - Silhouette colour / width / style
     - Pen for the corridor's outer silhouette (Top left-to-right,
       Datum right-to-left) — the single yellow dash-dot line sections
       drew before this feature shipped.
   * - Course-line colour
     - Reserved colour field for course-boundary lines; the shipped
       renderer currently draws course boundaries through the outline
       pens above.

.. list-table:: Annotations tab
   :header-rows: 1
   :widths: 25 75

   * - Field
     - Meaning
   * - Show slope/width labels
     - ``W=<width>  s=<slope>%`` labels on each segment of the
       corridor's top surface.
   * - Show point marks / Show point names
     - Marker + name for every named corridor point (``CL``, ``EPS``,
       …) carried on the section.
   * - Show area block
     - Per-station cut/fill/excavation-to-formation figures plus a
       per-material area table, drawn beside the section.
   * - Show legend / Legend per sheet
     - Material-color legend box; per sheet draws one legend for the
       whole sheet instead of one per section cell.
   * - Annotation text height
     - Pixel height shared by every annotation label.

The **Preview** tab paints a small synthetic section (two course
shapes plus a ground polyline) through the same renderer used for real
section views and sheets, so every field change is visible immediately
without building a corridor.

.. index::
   single: Material fills and overrides

Material fills and overrides
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Every course shape resolves its fill in this order:

1. **Override** — if the style has a row for the shape's material in
   the Corridor tab's overrides grid, that row wins: **Mode** (typed
   as ``solid`` or ``hatch``), and for ``hatch`` a **Pattern** name
   (e.g. ``ANSI31``, any pattern from the drawing's hatch-pattern
   library), **Scale**, **Angle**, and **Colour**.
2. **Material colour** — otherwise, the shape fills solid with its
   material's colour from the drawing's material library (the same
   library the Assembly Editor's **Materials…** button opens).
3. **Row-kind fallback** — untagged shapes (curbs, medians — see
   "Pavement structure" above) fall back to a colour keyed by row
   kind.

This is the same resolution the Assembly Editor's schematic preview
uses (see "Editor display" below), so a material recoloured via
**Materials…** updates consistently everywhere: assembly preview,
thumbnails, section views, and section sheets.

Add or remove override rows with the grid's **Add**/**Delete**
buttons; each row is independent, so a style can hatch-fill some
materials while leaving others solid.

.. index::
   single: Section style persistence

Persistence
~~~~~~~~~~~~

The style library is saved into the drawing (IQML/IQZ) under a
``CorridorSectionStyles`` element, alongside the other civil style
libraries.  Section views and sheets store only the style **name**;
resolution to a concrete style happens at draw time, so a missing or
deleted style name falls back to **Standard** without invalidating the
view or sheet.  Because assemblies and corridor sections were not
previously released, there is no legacy-drawing migration concern —
every existing view/sheet simply resolves as **Standard**.

.. note::

   The **Create Section Sheet…** dialog's Settings tab now includes a
   **Section style** combo (defaulting to **Standard**) so a new sheet
   can be assigned any style, including **Monochrome**, at creation
   time.  There is still no per-entity control to switch an *existing*
   view or sheet to a different style after the fact — use the
   **Preview** tab above to check how any style will render before
   that control ships in a later phase.

.. index::
   single: Conditional rows
   single: Cut/Fill condition
   single: Ditch
   single: Benching
   single: Ungraded

Conditional rows, ditches and benching
---------------------------------------

(Corridor v1.3 Phase 5.)  Three additions let an assembly's daylight
side adapt to the ground it actually meets, instead of always
resolving the same geometry: a per-row **Cut/Fill condition**, a
trapezoidal **Ditch** row for the cut side, and **benching** — tall
daylights broken into repeated lift-and-bench steps rather than one
long slope face.  A related geometry fix ships alongside them: the
daylight hinge now springs from the true edge of excavation on both
branches (see "The excavation-edge hinge fix" below).

Row condition: Always / Cut / Fill
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Every row in the Assembly Editor grid now carries a **Cond** column
(inserted right after **Name**), a three-way choice: blank/**Always**
(the row is unconditional — today's behaviour, and the default for
every existing row), **Cut**, or **Fill**.  A row set to Cut or Fill
only contributes its geometry, area, and section-view shapes at
stations where the corridor resolver decides that side of the
alignment is actually in cut (respectively fill) — at every other
station the row emits nothing at all, as if it had never been
authored.

The decision is made once per side per station, at the **daylight
hinge** (the point described in the hinge fix below): the resolver
probes the target surface directly above/below the hinge — ground
higher than the hinge means the station is in cut on that side,
otherwise it's in fill — then activates every Cut-conditioned row and
deactivates every Fill-conditioned row, or vice-versa.  The losing
branch is not merely hidden: it contributes zero to cut/fill/
excavation quantities, and its shapes never reach the section views or
section sheets, exactly as if it were pruned from the assembly for
that station.

In the Assembly Editor's live preview, conditional geometry is drawn
schematically on **both** branches at once so you can review each
side's design without building a corridor: the cut branch dashed and
tinted orange, the fill branch dashed and tinted green.  Only one
branch will actually resolve at any given corridor station, but the
preview always shows both so a conditional ditch or bench setup can be
checked without needing test ground.

.. figure:: ../../../images/element_ditch.png
   :align: center

   A cut-only Ditch row (orange, dashed) ahead of the daylight.

.. index::
   single: Ditch row kind

Ditch
~~~~~

**Ditch** is a new row kind for a trapezoidal drainage channel, added
with the **+Ditch** button under each side's row grid (next to the
other row-palette buttons).  A new ditch row defaults to name
``Ditch``, layer ``C-DTCH``, and condition **Cut** — it is meant for
the cut branch and is authored that way by default, though any
condition is legal if you have an unusual use for it.

.. list-table::
   :header-rows: 1
   :widths: 25 75

   * - Parameter
     - Description
   * - **Depth**
     - Vertical depth of the ditch invert below the point it springs
       from, in metres.
   * - **BottomWidth**
     - Width of the ditch's flat invert in metres.  **0 produces a
       V-ditch** (no flat bottom, the two slopes meet at a point).
   * - **ForeSlope**
     - Slope of the near (inboard) face, as 1:n (rise:run — e.g.
       ``2.0`` = 1:2).
   * - **BackSlope**
     - Slope of the far (outboard) face, as 1:n.  Edited in the row
       params dialog (double-click any P column of a Ditch row) rather
       than the grid, alongside Depth/BottomWidth/ForeSlope.

A ditch springs from the excavation edge exactly like an unconditional
daylight would, then walks down at **ForeSlope** to the invert, across
**BottomWidth**, and back up at **BackSlope** — and it is that rising
backslope which becomes the starting slope of the cut daylight chain
that follows it, so the ditch and the cut face read as one continuous
excavated profile rather than two unrelated elements.  The ditch's
own bottom also extends the excavation envelope: quantities'
**Excavation (to formation)** figure counts everything down to the
ditch invert on an active ditch, not just to the pavement datum, since
a ditch is simultaneously a finished-surface feature (it's what you
see) and a formation feature (it's what has to be dug).  A ditch row
draws as an open outline (no fill) using its own outline-colour slot
in the section style's Corridor tab, alongside Lane/Shoulder/Median/
Curb/Sidewalk/Slope/Generic.

.. index::
   single: Benching
   single: Ungraded

Benching
~~~~~~~~

Tall daylights no longer walk a single uninterrupted slope face all
the way to the ground: a Slope row can now specify **benching**
separately for its cut branch and its fill branch, each a triple of
**MaxHeight** / **BenchWidth** / **BenchSlope** edited in the row
params dialog (double-click a Slope row's P column).  Leaving
**MaxHeight** at its default of **0** disables benching for that
branch — the daylight behaves exactly as before.

With benching enabled, the resolver walks the active branch's slope
for at most **MaxHeight** of vertical rise/fall; if the ground
crossing is found inside that lift, the ordinary daylight point closes
the chain there (to the usual 1 mm tolerance) and benching never
engages for that station.  If the ground is not yet reached, the
daylight instead breaks outward: a bench point at the lift's top,
walking **BenchWidth** outward at **BenchSlope** to a second bench
point, then the next lift starts from there.  Named points appear
along the way — ``DL.B1``, ``DL.B1E``, ``DL.B2``, ``DL.B2E``, … — one
pair per completed lift, so section views and feature lines carry a
distinct point per bench.  Lifts repeat until the ground is met; a
hard cap of **20 lifts** stops the walk and flags that station
**Ungraded** on the command line rather than looping forever on
pathological ground.

The Assembly Editor's preview draws one schematic bench break — a
single jog partway along the branch's daylight stub — whenever a
branch's MaxHeight is non-zero, as a reminder that benching is active;
the preview's flat test ground can't show a real multi-lift walk, so
the schematic jog is deliberately just an indicator, not a solved
bench chain.

.. index::
   single: Excavation-edge daylight hinge

The excavation-edge hinge fix
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Both the cut and the fill daylight now spring from the **end of
excavation** — the outer bottom corner of a side's outermost course
stack, exactly where the excavation-to-formation envelope actually
ends — rather than from the shoulder's finished top edge as before.
Previously the daylight point anchored to the row chain's top link,
which sits above and inboard of a widened subbase or a taper foot;
because those courses are authored wider than the row itself (see
"Pavement structure" above), the true excavated face reached further
out than the daylight line implied, undercutting it.  Anchoring to the
excavation edge instead means the daylight — and any ditch feeding
into it — starts exactly where the dig actually stops.

A short connector link closes the gap down the outermost course
stack's outer face (from the row's top point to the excavation-edge
point) so the Top chain stays continuous for area and silhouette
purposes; on a side with no course stacks at all (e.g. a bare Generic
or Median row feeding straight into a Slope), there is no excavation
edge to speak of and the daylight falls back to anchoring at the
row's own top point, exactly as before this fix.

This is a **bug fix**, not a new option — every assembly with course
stacks on its outer rows sees its daylight (and, if you add one, its
ditch) start slightly further out and down than in earlier releases;
unconditional daylight-only assemblies otherwise resolve bit-identical
geometry.

.. index::
   single: Upgraded standard templates

Upgraded standard templates
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

All six templates in ``standard-roads.iqal`` (Rural-Narrow-2x3.0,
Rural-2x3.5, Urban-2x3.5+walks, Urban-Boulevard-2x2x3.25,
Highway-2x2x3.5+median, Freeway-2x3x3.75) now carry, on each side,
immediately before the closing Slope row:

- A **Cut-only ditch** — Depth 0.5 m, BottomWidth 0.5 m, ForeSlope
  1:2, BackSlope 1:1.5.
- **Benching on both branches** of the Slope row — 5 m lifts, 1.5 m
  benches, 4% bench slope.

.. note::

   On **Urban-2x3.5+walks** and **Urban-Boulevard-2x2x3.25** the ditch
   ends up sitting *behind the sidewalk* (Lane → Curb → Sidewalk →
   **Ditch** → Slope) — a cut-drainage ditch with no shoulder buffer
   ahead of it, which is unusual civil practice for an urban street.
   This is a literal application of "the ditch goes between the last
   row and the slope on each side" to templates that have no shoulder;
   the other four templates place the ditch after a shoulder, which
   reads normally.  Review this per project: edit the ditch's
   parameters, move it, or delete the row entirely on a copy of these
   two templates if a project doesn't want cut drainage immediately
   behind its pedestrian walk.

.. index::
   single: Condition and ditch/bench persistence

Persistence
~~~~~~~~~~~

Row condition, ditch parameters, and both branches' bench parameters
round-trip through ``.iqal`` (and the equivalent IQML) exactly like
every other row field: an unconditional row omits the ``condition``
attribute entirely (so pre-Phase-5 files still load with every row
defaulting to Always), a Ditch row always writes its four ditch
attributes, and a Slope row writes each of its six bench attributes
only when non-zero.  This is an additive extension of the existing v2
schema — no version bump was needed.

.. index::
   single: Standard sample library

Standard sample library
-----------------------

IQcad ships six pre-authored road templates in
``standard-roads.iqal`` (under ``testdata/library/`` in the
distribution).  An empty drawing's assembly library auto-loads them
the first time you open **Civil › Assemblies…** or run
``BUILDCORRIDOR`` — no manual import step is needed.  You can also
seed them on demand with ``SAMPLEASSEMBLIES`` (alias ``SAS``), which
is idempotent: assemblies that already exist by name are skipped.
The **Import** button in the Assembly Editor remains available for
loading additional/custom ``.iqal`` files from elsewhere.

.. index::
   single: Rural-Narrow-2x3.0

Rural-Narrow-2x3.0
~~~~~~~~~~~~~~~~~~

Low-traffic backroad.  Narrow lanes and shoulders with relatively
steep slopes — appropriate for mountain roads, forest tracks, and
single-family rural access.

.. figure:: ../../../images/sample_rural_narrow.png
   :align: center

   Rural-Narrow-2x3.0 cross-section.

**When to use it.** Low-volume rural backroads where right-of-way is
constrained and design speed is low (under 50 km/h).

**Composition** (per side; right side is mirrored):

.. list-table::
   :header-rows: 1
   :widths: 20 25 55

   * - Order
     - Element
     - Parameters
   * - 1
     - Lane
     - Width 3.0 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm AC
       + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase 30 cm
       (W+1.2 m, taper 1:1).
   * - 2
     - Shoulder
     - Width 0.5 m, CrossSlope −3%, peraltable.  Courses: Wearing 5 cm AC
       + Base 25 cm + Subbase 30 cm.
   * - 3
     - Slope
     - Cut 1:1, Fill 1:1.5

.. index::
   single: Rural-2x3.5

Rural-2x3.5
~~~~~~~~~~~

Standard symmetric two-lane rural road.  3.5 m lanes with 1.0 m
shoulders and 1:1.5 cut / 1:2.0 fill slopes daylighting to the TIN.

.. figure:: ../../../images/sample_rural.png
   :align: center

   Rural-2x3.5 cross-section.

**When to use it.** Most rural and inter-urban roads outside
settlements.  The slopes assume typical engineering soils; for rock
cuts use a steeper Slope row, for soft soils a gentler one.

**Composition** (per side; right side is mirrored):

.. list-table::
   :header-rows: 1
   :widths: 20 25 55

   * - Order
     - Element
     - Parameters
   * - 1
     - Lane
     - Width 3.5 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm AC
       + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase 30 cm
       (W+1.2 m, taper 1:1).
   * - 2
     - Shoulder
     - Width 1.0 m, CrossSlope −3%, peraltable.  Courses: Wearing 5 cm AC
       + Base 25 cm + Subbase 30 cm.
   * - 3
     - Slope
     - Cut 1:1.5, Fill 1:2.0

.. index::
   single: Urban-2x3.5+walks

Urban-2x3.5+walks
~~~~~~~~~~~~~~~~~

Urban street with kerb and sidewalk on each side.  3.5 m lanes,
0.15 m face-height kerb, 1.5 m sidewalk.  No shoulder.

.. figure:: ../../../images/sample_urban_walks.png
   :align: center

   Urban-2x3.5+walks cross-section.

**When to use it.** Urban single-carriageway streets with pedestrian
provision — the typical "residential collector" cross-section.

**Composition** (per side; right side is mirrored):

.. list-table::
   :header-rows: 1
   :widths: 20 25 55

   * - Order
     - Element
     - Parameters
   * - 1
     - Lane
     - Width 3.5 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm AC
       + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase 30 cm
       (W+1.2 m, taper 1:1).
   * - 2
     - Curb
     - FaceW 0.05 m, FaceH 0.15 m, TopW 0.30 m
   * - 3
     - Sidewalk
     - Width 1.5 m, CrossSlope −2%.  Courses: Slab 5 cm concrete + Base
       10 cm.
   * - 4
     - Slope
     - Cut 1:1.5, Fill 1:2.0

.. index::
   single: Urban-Boulevard-2x2x3.25

Urban-Boulevard-2x2x3.25
~~~~~~~~~~~~~~~~~~~~~~~~

Divided urban with central median and sidewalks.  Two 3.25 m lanes
per direction, narrow planted median, kerb and 2.0 m sidewalk.

.. figure:: ../../../images/sample_urban_boulevard.png
   :align: center

   Urban-Boulevard-2x2x3.25 cross-section.

**When to use it.** Urban arterials with pedestrian provision and
traffic separation — typical "city boulevard" cross-section.

**Composition** (per side; right side is mirrored):

.. list-table::
   :header-rows: 1
   :widths: 20 25 55

   * - Order
     - Element
     - Parameters
   * - 1
     - Median
     - HalfWidth 0.75 m, Depth 0.10 m, InnerSlope 1:10
   * - 2
     - Lane (Lane1)
     - Width 3.25 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm
       AC + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase
       30 cm (W+1.2 m, taper 1:1).
   * - 3
     - Lane (Lane2)
     - Width 3.25 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm
       AC + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase
       30 cm (W+1.2 m, taper 1:1).
   * - 4
     - Curb
     - FaceW 0.05 m, FaceH 0.15 m, TopW 0.30 m
   * - 5
     - Sidewalk
     - Width 2.0 m, CrossSlope −2%.  Courses: Slab 5 cm concrete + Base
       10 cm.
   * - 6
     - Slope
     - Cut 1:1.5, Fill 1:2.0

.. index::
   single: Highway-2x2x3.5+median

Highway-2x2x3.5+median
~~~~~~~~~~~~~~~~~~~~~~

Divided rural highway.  Two 3.5 m lanes per direction, 2.5 m
shoulders, 1.0 m central median.

.. figure:: ../../../images/sample_highway.png
   :align: center

   Highway-2x2x3.5+median cross-section.

**When to use it.** Inter-city divided highways with moderate
traffic.  Wider median templates can be authored by adjusting
HalfWidth on the Median row.

**Composition** (per side; right side is mirrored):

.. list-table::
   :header-rows: 1
   :widths: 20 25 55

   * - Order
     - Element
     - Parameters
   * - 1
     - Median
     - HalfWidth 1.0 m, Depth 0.30 m, InnerSlope 1:10
   * - 2
     - Lane (Lane1)
     - Width 3.5 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm AC
       + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase 30 cm
       (W+1.2 m, taper 1:1).
   * - 3
     - Lane (Lane2)
     - Width 3.5 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm AC
       + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase 30 cm
       (W+1.2 m, taper 1:1).
   * - 4
     - Shoulder
     - Width 2.5 m, CrossSlope −3%, peraltable.  Courses: Wearing 5 cm AC
       + Base 25 cm + Subbase 30 cm.
   * - 5
     - Slope
     - Cut 1:1.5, Fill 1:2.0

.. index::
   single: Freeway-2x3x3.75

Freeway-2x3x3.75
~~~~~~~~~~~~~~~~

Three-lane freeway per direction.  3.75 m lanes, 3.0 m shoulders,
wider 2.0 m median.

.. figure:: ../../../images/sample_freeway.png
   :align: center

   Freeway-2x3x3.75 cross-section.

**When to use it.** High-volume motorways and freeways.  For four+
lanes per direction, copy and add additional Lane rows.

**Composition** (per side; right side is mirrored):

.. list-table::
   :header-rows: 1
   :widths: 20 25 55

   * - Order
     - Element
     - Parameters
   * - 1
     - Median
     - HalfWidth 2.0 m, Depth 0.30 m, InnerSlope 1:10
   * - 2
     - Lane (Lane1)
     - Width 3.75 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm
       AC + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase
       30 cm (W+1.2 m, taper 1:1).
   * - 3
     - Lane (Lane2)
     - Width 3.75 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm
       AC + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase
       30 cm (W+1.2 m, taper 1:1).
   * - 4
     - Lane (Lane3)
     - Width 3.75 m, CrossSlope −2%, peraltable.  Courses: Wearing 4 cm
       AC + Binder 6 cm AC + Base 25 cm (W+0.6 m, stepped) + Subbase
       30 cm (W+1.2 m, taper 1:1).
   * - 5
     - Shoulder
     - Width 3.0 m, CrossSlope −3%, peraltable.  Courses: Wearing 5 cm AC
       + Base 25 cm + Subbase 30 cm.
   * - 6
     - Slope
     - Cut 1:1.5, Fill 1:2.0

.. index::
   single: Editor display
   single: Thumbnail list
   single: Course highlighting

Editor display
--------------

The Assembly Editor's live preview and assembly picker read like a
real cross-section rather than a wireframe — the shipped fills use
the same colors seen in the Rural-2x3.5 figure above.

Filled parts
~~~~~~~~~~~~

Every course shape fills with its material's color from the drawing's
material library: recolor a material via **Materials…** and the
preview and every thumbnail follow immediately.  Curbs and medians
carry no material reference yet, so they fill with fixed fallback
colors (concrete-grey and green respectively).  Course outlines draw
as thin grey lines over the fills; the Top and Datum lines keep their
existing (thicker, colored) styling.

Annotations
~~~~~~~~~~~

Lane, shoulder, and sidewalk rows show ``W=<width>  s=<slope>%`` above
their top link; daylight points show their ``cut 1:n / fill 1:n``
ratios.  Labels declutter automatically — a link drawn narrower than
40 px on screen hides its label; zoom in to bring it back.

Both daylight branches
~~~~~~~~~~~~~~~~~~~~~~~

At the daylight hinge the preview always draws both a schematic cut
branch (dashed, rising) and a schematic fill branch (solid, falling),
each 3 m long, in addition to the branch actually resolved against
the flat preview ground, which keeps its normal link styling.

Thumbnail list
~~~~~~~~~~~~~~

The assembly picker is a list of thumbnail + name rows to the left of
the preview, replacing the old name combo.  Selecting a row loads
that assembly into the left/right grids.  Thumbnails refresh
automatically on **Apply**, **Import**, **Rename**, and **Delete**,
and after material color edits.

Course highlighting
~~~~~~~~~~~~~~~~~~~~

While the **Courses…** dialog is open, selecting a row outlines the
corresponding course in cyan in the preview behind the dialog.  On
some systems the outline also updates live while the dialog is open;
on every system the highlighted course remains visible after you
close the dialog, until the next edit action (**Apply**, switching
the selected assembly, or adding, deleting, moving, or mirroring a
row) clears it.

.. index::
   single: Building a corridor

Building a corridor
-------------------

Once you have an alignment, a vertical profile, and an existing-ground
surface in the drawing, building a corridor takes four steps.

**1. Open the Assembly Editor.**
   ``Civil → Assemblies…`` opens the editor.  In an empty drawing the
   six standard road templates auto-load — the combo already lists them,
   no import needed.  Use **Import** only to bring in additional or
   custom ``.iqal`` files from elsewhere.

**2. (Optional) Author your own assembly.**
   Click **New**, give it a name, then click the row-palette buttons
   (**+Lane**, **+Shoulder**, etc.) under the left grid to add rows in
   order from CL outward.  Click **Mirror** to copy the left side to
   the right.  The live preview updates as you type.  Click **OK** to
   save into the drawing.

   For lane/shoulder/sidewalk rows, the **Courses…** button (one per
   side, next to the row grid) opens a modal grid listing every course
   in the row's stack — columns ``#``, ``Name``, ``Material``,
   ``Thickness``, ``Width``, ``SelfPt``, ``Target``, ``TargetPt``,
   ``EdgeL``, ``SlopeL``, ``EdgeR``, ``SlopeR``, ``DX``, ``DY`` — with
   **Add** / **Delete** / **Up** / **Down** buttons to manage rows and
   a **Material** combo populated from the drawing's material library.
   Click **OK** in the courses dialog to write the stack back, then
   **OK**/**Apply** in the assembly editor to commit it.

   The editor header's **Materials…** button opens the drawing-level
   material library: a name + colour grid with **Add** / **Delete**
   and a colour-picker button that recolours the selected row.
   Changes apply immediately to every course referencing that
   material's name.

**3. Bind the corridor to an alignment.**
   Open the **Alignment PI Editor**, select your alignment, switch to
   the **Corridor** tab.  Pick the assembly + target surface, set the
   sample frequency (default 5 m).

**4. Build.**
   Click **Build Corridor** (or run ``BUILDCORRIDOR`` from the command
   line, alias ``BC``).  Within a few seconds the drawing gains:

   - A **3D mesh** of the corridor body.
   - A **Top surface** (AECC_SURFACE) draping the road's running surface.
   - A **Datum surface** (AECC_SURFACE) under the pavement.
   - One **3D feature line** per named point along the alignment (edge
     of pavement, daylight line, etc.).
   - A **volumes report** on the command line: cut, fill, net,
     excavation-to-formation, and a per-material quantity table (see
     "Pavement structure — courses and materials" above).

If the status label reads **Out of date**, you have edited a source
(alignment, target surface, or library); click Build again to
regenerate the outputs.