Viaduct
The viaduct annotation builds what carries a track where the ground is far below it: a deck and piers under it, in masonry with arches or as a deck on piers. It follows the track round curves and up grades. You place and update it like any track annotation, with two markers at the ends of the stretch, see Getting started 3.
Style
- Masonry arches (default): piers, arches and the spandrel walls over them, one body with the deck. The model is the masonry viaducts of the Rhaetian Railway; the defaults are those of the Landwasser Viaduct.
- Deck on piers: a deck on separate piers, for a steel or concrete bridge or a ramp on posts.
Spans and piers
Span length is the clear opening you would like. The stretch is divided into equal spans as close to it as possible: a viaduct ends where its annotation ends, not after a whole number of spans.
With Abutments (default) the viaduct ends on a full pier at either end. Without, it ends on half a pier, for a viaduct that runs on into an embankment.
Pier offset slides the piers along the track until a span lies over whatever passes underneath, a road, a stream, another track. The track plan shows the piers dashed.
| Field | |
|---|---|
| Pier thickness, Pier width | along and across the track; width 0 means as wide as the deck |
| Pier batter | how much a pier widens towards its foot |
| Pier projection | how far a pier stands proud of the masonry. The ledge at the springing is the impost |
| Plinth height, Plinth projection | a plinth under every pier taller than it; 0 = none |
Height
The piers stand on a horizontal level, the Level height, such as the baseboard. With the level under a terrain, the feet of the piers disappear in the ground, however the terrain lies there.
The top of the deck lies under the track: Raily takes the track's construction depth off itself. Vertical offset moves it further.
Arches
Arch shape is round, segmental or pointed, Rise ratio the height of the last two. Ring thickness is the masonry between the crown of an arch and the deck.
Every arch is built level. Up a grade the arches therefore step from pier to pier, as built ones do, and each stays below the deck all along. Where the deck comes down, an arch grows flatter and finally becomes a wall.
Ring projection makes the voussoirs on the face stand proud of the wall, in a material of their own. It never stands further out than the pier the arch springs from; 0 = flush.
Deck
| Field | |
|---|---|
| Deck width, Deck thickness | |
| Parapet height, Parapet thickness | the parapet on both sides; height 0 = none |
| Cornice height, Cornice projection | the band at the top of the face that the parapet stands on; 0 = none |
| Lateral offset | puts the deck beside the track, positive to the right of travel |
One deck under two tracks
Put the markers on one of the two tracks, move the deck by half the track spacing with Lateral offset, and make it wider by the track spacing.
Materials
Structure material for arches and spandrels, Deck material, Pier material, Plinth material and Ring material can each be chosen. A plinth of rough stone under piers of dressed stone is as common on real viaducts as one built all of a piece.