When setting up the parameters for the strade module in Landbuilder a path to this type of file needs to be defined via the parameter LibraryFile.
By default the Strade_lib.cfg can be found in P:\tools\LandBuilder\libraries\ Strade_lib.cfg
But you can use your own version of this file and locate it (for example) in your terrain project folder.

The Strade_lib.cfg can be opened and edited via a text editor, but it would be wise not to edit the original.

What it does
The Strade_lib.cfg is a configuration file required by the Strade Landbuilder module which defines the different types of roads that can be created. The parameters within this file define the type of textures and 2d icon used, as well as the complexity of the models created and how they might be generated.

Class name
All road definitions are defined within class RoadTypesLibrary and follow a specific naming convention. Each road type must be defined as class RoadXXXX where XXXX is a number from 0001 to 9999 (always 4 digits).
There is no need to use consecutive numbers in the class names of differing roads, the following example works without error:


class Road0001
    class Road0014
    class Road0008

Example road definition
class RoadTypesLibrary
    class Road0001
        typename        = "highway";
        prefix          = "highway_";
        width           = 8;
        map             = "main road";
        mainStrTex      = "P:\tools\templates\textures\roads\sealed_paintedlanes_ca.tga";
        specStrTex      = "P:\tools\templates\textures\roads\sealed_paintedlanes_ca.tga";
        probSpecStrTex  = 0;
        mainCorTex      = "P:\tools\templates\textures\roads\sealed_paintedlanes_ca.tga";
        specCorTex      = "P:\tools\templates\textures\roads\sealed_paintedlanes_ca.tga";
        probSpecCorTex  = 0;
        mainTerTex      = "P:\tools\templates\textures\roads\sealed_paintedlanes_end_ca.tga";
        specTerTex      = "P:\tools\templates\textures\roads\sealed_paintedlanes_end_ca.tga";
        probSpecTerTex  = 0;
        minSpecDist     = 10;
        cornerRes       = 2.0;
        proximityFactor = 0.5;
        matchThreshold  = 0.1;
};The parameters

An identifying name for this road type, this name (value) is required for the strade module parameter type.

The prefix used when naming the road models created by landbuilder.

The named property used in the models created by landbuilder, this named property defines the type of 2d icon used to represent the road in vbs2.

The path to the texture used in the creation of straight roads.

The path to the texture used in the creation of secondary (random) straight roads.

The probability (percentage) of a secondary (random) straight road model being used.

The path to the texture used in the creation of road corners.

The path to the texture used in the creation of secondary (random) road corners.

The probability (percentage) of a secondary (random) road corner model being used.

The path to the texture used in the creation of terminating roads.

The path to the texture used in the creation of secondary (random) terminating roads.

The probability (percentage) of a secondary (random) terminating road model being used.

The minimum distance (in number of models) between two consecutive models using the "secondary" texture.

Note: All road models used in the example images below were created with strade parameter useSplines set to false, and at awidth of 8

The value for this parameter controls how many vertices are used in the creation of corner models, (how rounded a corner model is). A value of is considered standard but it can be as low as 1, (values below 1 seem to fail). 
The lower the value, the more vertices used to create the model (the more rounded the corner model). The value used approximately equates to the distance in meters between two (outer) consecutive vertices of the footprint of the corner models.
Corner road models can be made more rounded by lowering the number used in the cornerRes parameter, but at the cost of more demanding models.proximityFactor
This parameter defines how close to the centerline of the polylines strade will try to place road models as it builds the road network.
The value is used to multiply the current road's width to determine a threshold. To add a new road model to the current road, the strade module tries to place an instance of all the models, currently registered with the current road type. 
For each model, it calculates the "ending" position as if it was already added to the road (what will become the inserting position of the next road part). If the distance of this point from the polyline is less than or equal to the threshold, the model is accepted as valid candidate, otherwise it is discarded.

Perhaps an simple way to understand this parameter is: 
• The lower the value the more strade will try to place roads that closely follow the centreline of the polyline, but at the potential cost of the road having "kinks".
• Raising the value may smooth the formation of the road but at the cost of the road potentially not following the center of the polyline accurately.