Clearance gauge measurements

1 Purpose

This specification sets out objective requirements to enable suppliers to construct, produce and deliver a system for measuring the clearance gauge according to Jernbaneverket’s expectations.

A system as specified will enable Jernbaneverket to offer maximum infrastructure capacity throughout the state railway network with regards to utilising the clearance gauge and ensure safe train traffic within the gauge’s limitations.

2 Scope

This document covers the requirements for clearance gauge measurement equipment, installed on rolling stock. Requirements for construction, installation or rolling stock are not parts of this specification. Requirements set out by governmental authorities, i.e. The Norwegian Railway Inspectorate (SJT), shall be met. An integrated system of rolling stock and measurement equipment can be able to meet the requirements, equally to equipment installed on Jernbaneverket’s own rolling stock.

3 Data acquisition – accuracy

3.1 Gauge co-ordinates

The system shall be able to relate the co-ordinates of every single measured gauge profile to the plane perpendicular to the track plane (local, homogenous co-ordinate system). The system’s origin shall be the point midway between the rails in the track plane (track centreline).

There shall be no displacement of position between components measuring the reference system (centring of measurements) and the profile respectively.

Table 1: Accuracy requirements for profile data acquisition

3.2 Kilometre measurement and geometry

Travelled distance in the means of kilometre values is to be measured. Reset or calibration of this value shall be enabled. The track geometry shall be known by simultaneous measurements: To relate profile co-ordinates to the track, the track gauge must be measured. To calculate curve overthrow, cant (super elevation) and curvature must be measured:

Table 2: Accuracy requirements for track geometry measurements

Track gauge measurements can be replaced by another measurement system for centring the co-ordinates. If so, this ought to be included in the total measurement accuracy according to table 1.

3.3 Measurement density

Maximum distance between every profile is 100 mm.

4 Data acquisition – functionality

4.1 Measurement modes

The measurement system shall acquire profiles (single frames) even when the equipment stands still. Hence manual data acquisition should be enabled so that exact locations can be measured more thoroughly and accurately. In these cases making text remarks during measurement runs shall also be possible; to identify the variations in the results, preferably as pre-defined codes for specific reductions in the clearance gauge.

Pre-defining a specific gauge/profile in front of an acquisition shall be enabled, to make the measurement run a direct analysis itself.

Pre-defining a specific gauge reduction/safety distance in front of an acquisition shall be enabled, to make quantities like distances shorter than the safety distance, or largest reduction on the section, presentable.

4.2 System requirements

The system shall be able to measure at a minimum speed of 50 km/h.

Required measurement range from origin: y: +/- 5 m, z: + 9 m.

Data acquisition shall be possible in all light conditions from broad daylight to darkness, as well as under temperatures within -35 °C ≤ t ≤ 30 °C.

The actual clearance gauge behind shorter installations within the gauge should be visible to the system during measurements or detectable in later analysis.

The contact wire shall be visible in the measurements for every whole meter (every 10^th frame/gauge picture) or more often.

5 Measurement results/report

5.1 Graphical presentation

Each single frame is to be presented as a report/picture.

The drawn clearance gauge shall be presented with an adequate number of co-ordinates for easy interpretation, although detailed to such an extent that all reductions are presented.

5.2 5.2 Text field

For every frame/picture, the following information shall be provided:

• scale
• date and time for the acquisition
• identity for line and track number
• measured geometry: curve radius and cant
• kilometre position in Jernbaneverket’s kilometric system
• pre-defined codes for every type of reduction/text inserted during measurements
• unique number for every file/picture for each profile
• if given in advance: the type of theoretical clearance gauge to compare the measurements to
• named tunnels, railway bridges, number/name of outliers etc. (in manual mode)

5.3 Export of gauge co-ordinates

Gauge co-ordinates are to be exported in a readable format. Exporting single frames shall be enabled through an adapted dialogue.

6 Analysis/Post processing

Jernbaneverket currently administrates both tools and human resources to carry out analyses and simulations of clearance gauges from readable format co-ordinates and single frame profiles.

An integrated system also containing software for analysis is considered to meet this specifications requirement, even if some of the single frame functionality described in chapters 4–5 is not fulfilled. If made available, such a system shall not limit the number of users within Jernbaneverket. It is however accepted that Jernbaneverket cannot deliver the tools to a third party, while measurement results on file or paper prints can be made available to a third party.

An integrated system including analysis/simulation tools shall above all enable the possibility to simulate a theoretical load- or wagon gauge against the measured clearance gauge to calculate the safety distance between the two, hereunder the possibilities to:

• Define a random load- or wagon gauge by means of inserting co-ordinates. As required for the measured clearance gauge, co-ordinates shall be given in the plane perpendicular to the track plane (local, homogenous co-ordinate system) with the origin as the point midway between the rails in the track plane (track centreline). Pre-defined sets of such co-ordinates are to be saved on file.

• Define a specific length of the rolling stock (load- and wagon gauge), in addition to characteristic geometry of its <løpeverk>, in order to relate the calculated safety distance to real curve overthrows.
• Calculate safety distance as minimum horizontal distance laterally and minimum vertical distance vertically.
• Limit the number of detected reductions in the clearance gauge by defining a minimum safety distance needed, in order to reduce the <datamengden> in the analysis result.
• Print numerical arrays that document the locations where reductions have been detected, including safety distances respectively.
• Generate graphical plots of load- or wagon gauges printed together with the measured gauge at the locations where reductions have been detected.
• Export the results to standard numerical tools like i.e. Excel.

7 Check list