Sets of Lines
In the 1.2 Sets of Lines window, we define the "moving lines" of the loads. For both lanes we define two sets of lines.
The moving step Δ must be the same in both sets of lines in order to let the loads move parallel.
The description Lane 1 makes the assignment easier later.
In the List of Lines section, we specify the numbers of the two longitudinal border lines serving as "guiding lines" for lane 1.
With the 
button you can define these lines graphically.
The order of numbers determines the moving direction!
We specify the Moving step Δ with 5 m. So every 5 m a fixed point is created for the loads.
In the Eccentricity section, we enter a lateral distance of -2 m in order to shift the guiding line to the center of the lane which has a width of 4 m. In our example, you must enter the distance with a negative value because the loads are acting left in the lines' viewing direction (see image above).
Create a second set of lines with the [New] button. Enter Lane 2 as the description.
In the List of Lines section, we define the numbers of the lines lying on the opposite side of the lane. They serve as a guiding line for lane 2. Again, the order of the lines determines the moving direction.
The Moving step Δ is again 5 m so that the loads in both sets of lines are moving parallel.
In the Eccentricity section, we enter a lateral distance of 2 m in order to shift the guiding line to the center of the lane which has a width of 4 m. This time, the distance is a positive value because the loads are acting to the right of the set of lines (see Image 6.4).