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Tunnel Parametric Description

Use this dialog to define a parametric description for a tunnel.

Where can I find the dialog?

In the toolbox, select SFI Properties..., go to the Tunnel tab, and open the Tunnel Descriptions table.

Using the dialog

The dialog has a dedicated preview window, as well as the ability to change which profile you want to view.

Note

It is not possible to zoom in the preview window. In cross-section editing, there is also a preview directly in the cross-section, where you can zoom and, for example, measure distances. Material types are also updated when editing the table.

Layer 30: Tunnel

Standard tunnel types

According to the handbook, the following standard profiles are defined:

  1. T4
  2. Profile series T5.5, T8.5, T11.5
  3. Profile series T7, T9.5, T12.5

When you select one of the standard profiles, the program will retrieve the parameters as defined in the Norwegian Public Roads Administration's tunnel handbook.

Parametric tunnel type

A parametric tunnel type allows you to define a general parametric profile in addition to the standard profiles. In this case, you enter the values manually. You can check options for straight walls, flat roof, and transition radius. The options you select determine which parameters become active. The figures below show what the different parameters refer to.

Angle \(\alpha\)

Transition radius \(R_t\) and Angle \(\beta\)

Asymmetric tunnel type

For asymmetric tunnel types, you can also choose a straight wall on only one side.

In the figure, there is a straight wall on only one side

IWR asymmetric tunnel type

For IWR asymmetric tunnel types, you can rotate the walls independently of each other.

Connection surfaces for tunnel profile

The tunnel profile is connected to road surfaces. The connections are found in the columns V.Conn. and H.Conn.. These surfaces must exist for the entire interval. The program automatically finds the correct tunnel profile along the road if the surfaces change width. Between standard profiles, the parameters are adjusted so that you get transitions without breaks. You cannot change the parameters manually.

Tunnel rotation

You can choose whether the tunnel profile should rotate with the road or not. The settings for this are found under Tunnel Rotation.

You can choose between several methods:

  1. None
  2. Rotation given by slope between
  3. Left-right independent rotation

For tunnel profiles, except for IWR asymmetric, the rotation line is determined by the values given in the fields for Left surface and Right surface. For IWR asymmetric profiles, there are three rotation lines: one for the left wall, one for the right wall, and one for the entire tunnel. For IWR asymmetric tunnel types, the program will use the surfaces entered under Independent wall rotation... to find the rotation lines for the left and right walls.

There is a difference between the terms road width and tunnel width for rotated tunnels. Road widths are always measured horizontally, while tunnel widths are specified relative to the road surface. Since the road surface is usually not horizontal, but rather slopes down to the left or right, there is a difference in the nominal distance between the road surface and the tunnel walls.

Figure: A = Nominal road width, B = Contraction

We want the tunnel width to be equal to the nominal distance between the connection surfaces, for example, -2.1 and 2.1. Since the tunnel is rotated with the road, we must move the intersection points between the wall and the road surface inward. With the Neutral contraction point field, you can control where this contraction will occur. If you select a point in the middle of the tunnel contour, you will get equal contraction on both sides.

The surface for baseline elevation is only relevant for unrotated cross-sections, i.e., tunnel rotation method set to None. With this option, you can set a surface number other than 0.0 as the elevation for the tunnel's baseline.

Layer 31: Tunnel blasting profile

For tunnel blasting profiles, it is common to use type Parallel or Parallel straight walls.

Parallel

Parallel straight walls

For parallel straight walls, you can choose both sides, or only the right or left.

These types require that layer 30: Tunnel is created. You specify the distance in the Value column.

The tunnel blasting profile is constructed to the intersection with the trough.

Blasting profile constructed to intersection with trough

How does the program calculate the curve end point (the transition between line and curve)?

A temporary parallel to the tunnel profile's rotation surface is created through the road gradient's circle center. Where this parallel intersects the tunnel profile, you find the curve end point. Usually, this is 1.57 m above the vertical curvature.

If you want to create a parallel to IWR asymmetric, you must also specify which surfaces the straight walls should be normal to. You enter the surfaces in the columns V.Conn. and H.Conn..

Layer 32: Drive box

Tunnel type Box is used for the driving space. You specify the height of the drive box directly in the Value column. You can have several drive boxes, for example, one continuous drive box through the entire tunnel (linked to surface edge -1,1 and 1,1) and a separate drive box in the niche (linked to, for example, surface edge -2,1 and -1,1).

Convert to manual

With this option, you can convert a parametric tunnel description to a manual tunnel description. How the program performs this conversion is described below.

The conversion first creates cross-sections for each meter, at the horizontal curvature's curve point, and at parameter changes in the tunnel description. For roads designed with the parametric method, cross-sections are also created at parameter changes in broken slopes and road parameters.

The function then temporarily builds the tunnel layers in the cross-sections. From these tunnel layers, unrotated contours and a rotation table are created in the manual tunnel description.

Finally, redundant contours and rotations that can be recreated from neighbors are removed.

Warning

Before conversion starts, any manual layers will be deleted.

Import of Vianova tunnel description

NovaPoint Tunnel has its own format for parametric tunnel descriptions. You can import such files into SFI model using the NovaPoint Tunnel (.XML) option. Note that you do not get fully constructed layers (only the parameters) in the same way as when importing a VIPS project from NovaPoint Road.

Tip

Here is a suggested verification method:

  1. Ask the design consultant to include cross-section drawings for critical profiles in NovaPoint Tunnel, where the slope annotations are shown for both the inner tunnel profile and the blasting profile (also called the perimeter).
  2. Manually compare these profiles with those calculated in Gemini Terrain. Accept the result if the slope deviations are less than 5 mm.

Example of comparison between NovaPoint and Gemini Terrain

What constitutes critical tunnel profiles can be discussed, but at a minimum, it should be the start and end profile within each parametric tunnel "package," as well as profiles where the road surfaces change dramatically. The designer should be able to determine this themselves.