Unlike switches (turnouts)  which only have two states – direct (main) route or deviated (branch) route – double slip switches or DSS are more complex to configure in the context of routes, on the one hand because of their own properties, on the other. depending on the which type of junction model used.

This article will not seem to provide the reader familiar with EEP with any new information, but it will allow newcomers to fully understand the internal structure of a crossing-junction in order to be able to correctly program the track contacts in a route.


The different types of DSS (Double Sip Switch / junction)

Fig 1: Double Slip Switch in EEP

Figure 1 above shows an example of DSS in EEP. The difficulty of setting the positions of a Crossing-junction requires knowing the internal structure that hides behind its appearance as we can observe it in this photo.

In EEP, there are 4 possibilities for creating DSS :


  1. DSS with movable blades : These DSS are available ,after purchase, in the EEP shop. They are very well made, carefully modeled and therefore very realistic (Fig 2). They offer the advantage of having the mobile blades showing their movement when a change of position is activated. However, they have several disadvantages described just after the “railway object” DSS.
Fiig 2 : TJD à lames mobiles
  1. Railroad ObjectsDSS : EEP offers one-piece DSS, accessible in the Railroad Tracks Editor – “Railway Objects” tab, identical to the mobile models except that they have no moving parts. Let us now examine the disadvantages of these first 2 types of DSS. I would like to emphasize that these are not absolute drawbacks but that these models, in relation to the use we want to make of them, can actually present inconveniences, which is the case for DSS that we want to use in the context of complex routes:
    • These switches and crossings can not be modified. It is not possible to modify either the length or the angle of deviation. In other words, the user of this type of DSS can not adapt the model to the characteristics of his network but must on the contrary adapt the layout to the characteristics of the DSS. Such switches do not make it possible to faithfully follow the layout of the tracks, in particular from real network plans.
    • More troublesome, the setting of the DSS in an automation is much more delicate. It seems that these DSS are more easily programmable using Lua in the context of routes.
    • The mobile DSS are fitted with a side lantern, a characteristic specific to German switches and crossings. The user, concerned about realism, who wishes to use these DDS for an Sncf type network can not remove this lantern as he can do with the switches built manually in EEP. Of course, this inconvenience is no longer one, if the modeler envisages the construction of a German network.
  1. The so-called “predefined” DSS : The prefabricated DSS, available in the drop-down menus ” Track combinations” then “Standard combination”, themselves accessible from the “Assemble” section appearing in the menu bar at the top of the 2D and 3D windows. Two models are proposed, having the same characteristics, namely angle of deviation of 6.4°, radius of 190 m and lane spacing of 4.5 m. The only difference is that one is offered as left DSS, the other as right DSS. This distinction, in my opinion, has no reason to be when we know that a DSS is strictly symmetrical with respect to its longitudinal axis. The figure below shows 2 DSS, the top one being “right” and the bottom one “left”. Once positioned in a network, the predefined DSS show no difference in their orientation. (See figure 3 below).
Fig 3: Predefined DSS
  1. Custom DSS : The fourth and final option is, of course, custom building a DSS. This requires, beforehand, knowing the structure, which we will see below, but above all requires some practice. Everyone can be reassured, this does not require a high-level of skills but, as I have just said, just a minimum of practice to obtain a neat track device that is pleasing to the eye.

The structure of a DSS

To fully understand the structure of a DSS, all you have to do is place one in the 2D window, taking great care to isolate it in order to locate the switches that make it up. Figure 4 below highlights the switches at the ends of each crossing-junction branch.

Each turnout is connected to the opposite turnouts by straight or curved rail sections:

Fig 4: Predefined DSS

Figure 5 shows a “disassembled” DSS. We have the 4 switches, here identified from 1 to 4 and for each of them a connection with 1 straight rail and 1 curved rail.

For example switch 1 is connected to the opposite switches by straight or curved rail sections. Thus it is connected to 2 by a curved rail and to 3 by a straight rail.

The two straight rails allow the crossing of the DSS diagonally and intersect in their center. Here we can identify these 2 straight rails, one connecting 1 to 3 and the second 4 to 2.

Fig 5: Elements of a DSS

It will be ensured at the time of the installation of the DSS in the network that the 4 switches are well programmed “Main” in straight route – from 1 to 3 in the present case for switch 1 – and “Branch” in route curve – from 1 to 2 for this same turnout. If this is not the case, simply select the turnout and open its settings window and click on the instruction “Swap the main branch with the branch position”. We will thus obtain “Main” for programming in a straight line and “branch” for the curved route, which is more logical and will avoid programming errors later on.

Fig 6: Swap main and branch

Setting of a DSS

Predefined or custom DSS

As soon as the structure of a DSS is perfectly known, its programming within the framework of the routes poses no difficulty, this operation simply amounts to configuring the switching of the entry point of the route. It is not necessary to configure the exit switch in so far as it can be pushed. In the case of “predefined” turnouts as for those built personally, the programming of the route in a DSS simply amounts to displaying the desired position in the contact for the turnout entry .

DSS Railway Objects

In the 2D window, the “railway object” type DSS present a green icon with 2 small mobile red segments. The position of these 2 segments actually materializes the position of the DSS itself.

Fig 7: DSS type railway object with its icon

The following figure displays the four possible positions of a DSS with the demonstration of each of them, as it appears in the drop-down menu of a contact switch.

Fig 8: Positions of a DSS railway object

Figure 9 reproduces the “Positions” drop-down menu allowing you to choose the desired position. It is advisable to check with the green icon that the position selected in the drop-down menu actually corresponds to that requested because errors are quite frequent.

A simple verification trick is to put a contact on the track just before entering the DSS (regardless of the type of contact) and to slide it through the DSS to ensure that it comes out of it at the desired location. After this check, the contact is deleted if the position is validated. Otherwise, the operation is repeated until the correct result is obtained.

Fig 9: Drop-down menu of DSS railway object

The signal slip switch / junction (SSS)

In this last part we well discuss single slip switches ( junctions ). If they are covered in the same article as the DSS, it is because they are designed on the same principle as their big sister, namely that the 2 exit bifurcations are made using the entry switches.

However in a SSS not all entrances are equipped with a switch. Only 2 entrances are equipped with it, which limits the possibilities.

Fig 10 : DSS versus SSS

In photo 10 above we can compare the structures of a DSS (top device) to that of a SSS (bottom device). Thus, we observe that the DSS is equipped with 4 switches, one per input-output branch. The presence of switches is materialized by yellow arrows and their motor by a red circle.

The lower device shows that only two opposite arms are equipped with switches, also materialized by arrows and circles. This obviously limits the possibilities of bifurcation in one direction or another.

Figure 11 below shows the possibilities of a single slip switch. This figure should be compared with figure 8 above relating to DSS.

It can thus be seen that taking a “left – left” deviated curve is made impossible due to the absence of switches at the entrances to this route.

Apart from this restriction, the characteristics of a DSS remain completely similar to those of a SSS and consequently the configuration remains identical, except that it offers fewer possibilities.

Fig 11 : DSS versus SSS

At the end of this article which, as I mentioned in the introduction, will not bring really new elements to experienced users, I simply hope that it will allow beginners or those who still lack practice to have access to all the necessary information, immediately usable, to use double slip switches / junctions and configure them appropriately.

The DDS are switches and crossings which constituted, at the time, a brilliant technological invention by allowing bifurcations in 4 directions in a limited space and thus facilitating the movement of trains, particularly in station sidings. In a network of virtual model making they bring the same advantages and using them can only be beneficial. So don’t hesitate to use them!

Article written by François. Contact

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eep-world.com team

This article was translated by Pierre for the English side of the EEP-World from the article written by François for the French side of the EEP-World.

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