Dataset description

Documentation Code	Test Title	Exchange Code	Test Code	Author	Data Owner	Version	Date
IFC4.3AbRV_E2a_SP01	(RFI) Track structure for single track	E2a (TRAS)	SP01	Evandro Alfieri	RFI	1.0	DD.MM.YYYY

Model Dataset

This test case utilises the following dataset.

Filename	Type (format)	Description
TrackCrossSection	drawing (png)	Track cross section to be used as example
Cant-CantAngle	figure (png)	Information on how cant is applied to rail
CantFromLowerRail	figure (png)	Information on how cant is applied to rail
SleeperPlacement	figure (png)	Information on how to position sleepers along the alignment
RailProfile60UIC	drawing (jpg)	Drawing of the rail profile E601 (aka, UIC 60) to be used
SleeperExampleRFI230	drawing (png)	Example of shape and tolerances of a concrete sleeper

Track Cross Section

The image below shows the different elements of the track super-structure (green in picture) to be represented. (For the track sub-structure part, red in picture below, refer to test case IFC4.3AbRV_E2a_SB01.)

From bottom-up:

the ballast bed
the sleeper
the two rails

Applied cant

In a cross-section plane, orthogonal to the track axis, it is the difference in height (h_t in the picture below) between two points, of the track plane, that have a conventional distance between them of 1500 mm (known as Rail Heads distance). For this test, the cant is always applied to the external rail (the furthest rail from the center or the curve). Thus, cant is measured from the lower rail (inner rail)

NOTE:

The dataset for this test comes from an Italian stakeholder (RFI). In Italy, only straight line is used for cant segment
The RailHeadDistance (light blue in figure below; or 2b₀ in figure above) is a normalized value used to compute the angle of cant. RFI uses 1500mm for a track gauge of 1435mm.

Straight and curved parts

The sub-structure part (red) is not influenced by cant. So, it is expected to have the same representation both in straight parts and in curves. The super-structure (green), has a different behaviour for ballast and sleeper in curve, compared to straight parts.

As depicted in the image below, and as stated in the Applied cant section, the inner rail is the lower rail. This stays fix, while the outer rail rotates (goes up).

The detail below shows how the ballast bed profile changes in curve. Note how:

Maximum cant allowed (in Italy) is 160 mm
The highest point of ballast on the side of each rail (red dot) is always, even in the straight part:
- 1050 mm outer the inner edge of the rail head profile
- 100 mm above the bottom edge of the rail profile
And from that, the ballast always maintains the 4/3 ratio for its slope

Sleeper placement

The image below capture some details about the placement of sleepers.

Sleepers are linearly positioned along the alignment
The reference for their positioning is the alignment curve (horizontal + vertical)
The span between the sleepers is 660 mm, measured on the horizontal plane
Their orientation is affected by cant
Considering the insertion point (O) being the one showed in picture below, the sleeper is positioned with an offset from the alignemnt curve
This offset is influenced by cant (as this offset is always perpendicular to the track plane)
The success of the test is independent from the choice to use a detailed sleeper (up-right) or a simplified sleeper (bottom-right), as the relationship between the origin of the sleeper (O) and the alignment curve (A), as showed in picture, is not affected by the geometric detail of the sleeper's shape.

Rail profile

The image below shows the profile section of the international UIC 60 rail profile. This has to be considered just a reference, as the success of the test is independent from the rail profile used. For the sake fo test, any simplified profile is equally accepted.

IMPORTANT: the rail profile shall be defined once, and then the track is created making two offset of the same profile - as to create two instances for the two rails.

Eventually, if a software vendor decide to go for the real situation (see picture above for sleeper placement), where the rails are slightly tilted inward. Then the rail profile, other than being offset twice, is also rotated.

Sleeper example

The image below shows the shape and tolerances for a type of concrete sleeper (RFI 230). This has to be considered just a reference, as the success of the test is independent from the sleeper type used. For the sake fo test, any simplified profile is equally accepted.

Where:

L = 2300 mm
b₁ = 300 mm
Height of sleeper in proximity of the rail = 170-190 mm