Abutments without bridges

Two supports stand in the terrain, and what once joined them depends on the document you are holding. Choose a document and see how much may be drawn in the void between them.The drawing shows how much may be drawn in the void between them when the document declares the extent of its description.

The document describes part of the gap; the rest stays empty.

A model diagram, not a photograph or a map. Both axes at the same scale.

A model diagram, not a photograph or a map. You set the dimensions yourself, and none of them describes a particular structure. Both axes have the same scale.

support surviving in the terrain (diagram)
geometric line from a scaled plan
extent of description in the document (declared)
void in which nothing has been added
open column with a “?” above B: height not established (only without a scaled plan)

Seat B is 2 m higher than A at a spacing of 60 m. The dashed line is the geometric line between the seats, not the outline of a structure. The red annotation shows how many metres of the gap the source describes (from A, in plan). The rest, 36.0 m, stays empty and has no outline at all.

Line length D: 60.03 m
Line gradient i: +33.3 ‰
Described in the document: 24.0 m of 60.0 m
Gap with no description: 36.0 m

What are you holding, and what may be drawn from it?

First choose a document, then set the model. The drawing will never fill the void, because this bench has no “show the whole bridge” button.

Without JavaScript you see the default state of the drawing (documentation with an extent of 24 m of 60 m). The sliders, the pier checkbox and the reset button are hidden then, because they would change nothing, and the four levels of material below work as a table: what they allow to be drawn and what they do not.

Evidence

Just the masses of the supports in the terrainAllows: stating that two supports stand there and what they look like.Does not allow: measuring the gap, treating A and B as one crossing, or drawing anything between them. Site sketch or unscaled mapAllows: linking A and B into one route, as the author of the sketch claims.Does not allow: stating a distance, a height difference or a gradient. Plan of the supports with scale and levelsAllows: measuring L and Δh and calculating the geometric line between the seats.Does not allow: describing the structure, material or date of the span. Documentation with a declared extent of the spanAllows: marking how many metres of the gap the source describes, counting from support A.Does not allow: adding the rest, or treating the declaration as proof of existence and date.

Model geometry (exercise)

Seat spacing L60 m

Height difference of the seats Δh+2 m

Positive: seat B higher than A. The model range is ±12 m.

Extent of the span’s description in the document, from support A24 m

Active only with documentation that gives an extent. Metres in plan, never more than L.

Surviving intermediate pier at mid-gap (top assumed to lie on the line)

Always outside the drawing, whatever the document

Whether A and B are one crossing and one periodThe document declares this. To be checked in the source itself.
Structure and material of the span24.0 m described (the document’s declaration); the remaining 36.0 m is not established.
Date and cause of disappearanceDoes not follow from the geometry or from the number of metres. It requires dated evidence, and the absence of a span does not immediately mean war.

Limits of the drawing and the rule of observation

Model assumptions

The scale is shared by both axes, so that the gradient of the line looks as the numbers imply. The extent of the description is counted from support A, in plan. The top of the pier, if you switch it on, lies on the geometric line. The line is a segment between the seats, not a structural design. The abutments in the drawing are a diagram: they do not depict any verified structure. Thresholds from railway standards are not applied here, because the slope does not decide the function of a ruin.

The rule of observation

1. Observation point: a public road, footbridge or trail, far from the object. It is not the location of the object.
2. Zone around the object: do not enter. Do not climb the abutments, and do not walk onto the trackbed or the embankments.
3. The object, viewed by eye or with a camera from a distance. Assessing the stability of the structure is a matter for a specialist, not for this page.

This page gives no coordinates, approaches or routes. The diagram of the rule is not a map.

What was removed from version V2, and why

The choice of girder, truss or arch, and the drawing of a truss. Removed. They added exactly what is missing, while the subject is the refusal to add it. Replaced by an empty, hatched field.
Percentage documented. Replaced by the metres of the declared extent. A percentage suggested a measure of how true the whole reconstruction is.
Three ready-made sets A, B, C. Replaced by four levels of material, because it is the material, not the geometry, that decides what may be drawn. Set A and the geometry of set B (L, Δh, pier) can be approximated with the sliders, but without the truss and the percentage. Set C (Δh = 15 m, no document) cannot be recreated: Δh was limited to ±12 m, and without a plan the geometry is not established.
A log of field notes in browser storage. Removed. It is not needed to understand the subject, and the page no longer stores anything. The rule of observation remains as a short diagram.
A photograph of a viaduct loaded from the internet. Removed from rendering, because the page is meant to work offline. A clickable link to the file on Commons remains.
Δh range of ±20 m. Narrowed to ±12 m so that, with equal axis scales, the drawing fits the frame of a phone and a computer.
Kept from V2: the line length D as the hypotenuse of L and Δh, the gradient in per mille, the spacing L of 0–85 m, the levels of material, the optional pier, the reset and the link to the NID report.

Sources and what is missing

Narodowy Instytut Dziedzictwa — Zabytki architektury i techniki kolejowej [Monuments of railway architecture and technology] (report, PDF) A framework for documenting railway heritage. The link was carried over from V2; it was not opened when this page was built, so it needs checking. The report is not a register of any of the supports shown in the drawing.
Wikimedia Commons — railway viaduct in Ludwikowice Kłodzkie, 2016 Photo: Jacek Halicki, licence CC BY-SA 4.0 as stated in the V2 caption (not checked again). This is a surviving viaduct, technical context, not abutments without a bridge. The photograph is not embedded on the page.
Version V2 of this page and version V1 Links between versions. The integrator will check that the targets exist after deployment.

Missing and still to be obtained

Photographs from legal observation points, with a caption, author and licence.
Archival plans of specific crossings, indicating the line and the period.
Dated evidence of the fate of the bridges. Without it, the date and cause of a span’s disappearance remain unknown.
Assigning each pair of supports to a single crossing. Only then can a real structure be shown instead of a diagram, and a map of safe viewing points only at the very end, after checking.

The whole page is a model and an exercise. No dimension, extent or slope describes a real bridge.