Project 0900 NR Cambrian

To supply the existing SMDI21 'proof of concept' to Network Rail (NR) and/or their contractors (collectively known as 'the users') for use in the Cambrian ERTMS project.

The system allows the users to create CAD drawings (detailed in this proposal) showing ‘As Is’ signalling asset data directly from digital survey data and digital mapping data.

Both the survey data and the mapping data are supplied by NR.

The system can be installed directly on the users computers or, at additional cost, can be supplied on a laptop configured by dhp11.

Key Concepts

There are a number of key concepts that need to be understood before this proposal makes sense.

Data Sources

The system imports track and asset data from comma separated (CSV) files. This data is probably output from OmnicomSurveyor3D? - but this is not the only possible source. Any CSV file that meets the specification detailed later in this document can be used as input to SMDI. For example track centre line and infrastructure data has been successfully imported from Google Earth Railway Mapping System (GERMS)1.

As background information SMDI uses vector and raster digital mapping data. This data has probably been supplied by Ordnance Survey Great Britain, but again - this is not the only possible source. Any MicroStation compatible digital mapping information (raster or vector) that is spatially referenced to the British National Grid can be displayed. For the purposed of this proposal only data supplied in OS-MasterMap format is acceptable.

Data Formats

The SMDI stores two types of data in two different ways.

Spatial data, e.g. track centre lines, the location of signals etc. is stored in a MicroStation design file (DGN).

Attribute data, e.g. the name of a signal or the type of a piece of track side equipment etc. is stored in an XML file.

Drawing Types

Because MicroStation design files are the digital replacement for paper drawings they are often referred to as 'drawings'. SMDI has three drawing types:

The first is the Geographic Representation, or more simply - the Geographic. This file contains a 3D model of part of the railway (built up from the data in the CSV import files), spatially located according to the British National Grid. The geographic is effectively a map, so the distance between features is the real world distance.

The second type of drawing is the Layout Plan. This file represents a section of railway in a one dimensional (or linear) form. All distances are correct with respect to the route centre line.

The third type of drawing is the height profile. This file represents a longitudinal section along a route centre line or track and is used to calculate gradients.

All drawings have an accompanying XML file contain textual (i.e. non-graphical) information.

Datum Distance

A point can located by specifying its 3D coordinates, i.e. (X,Y,Z). It can also be located by specifying its linear distance along another feature. Strictly we would specify the linear distance and the perpendicular offset (chain and offset) but quite often the linear distance (or chainage) is sufficient.

The with very long linear elements is deciding where they start. We address this not by identifying the start of the element, but by identifying a known point on the element and explicitly stating it's distance from the start of the element. We call this known point a 'datum'.

So a point 100m away from a datum with a value of 8760m would have a datum distance of 8860m if measured in the direction of increasing chainage, or a datum distance of 8660m is measured in the direction of decreasing chainage.

Therefore a datum has: an (x,y,z) location and a value. It is also associated with a linear element (a route centre line) and it also has a direction.

See Also

• [http://www.dhp11.com/site04/project/0900/ Project Directory]