This article goes into detail of the ATB Safety System included in the Spoorlijn Zwolle – Groningen route Add-on.

ATB-Eg or 'First generation' covers the signal pulse codes and cab speed enforcement.

ATB-Vv or 'Improved version' includes track magnets installed at select Stop signals, which provide increased protection.

The ATB system consists of two parts; one within the track and signal infrastructure to generate pulse codes, the other onboard the train to interpret and enforce speed restrictions.

Note: Codes 270 and 147 are not used. Whilst some onboard equipment is capable of reading these, the codes have been disabled or removed from use from track side infrastructure.

When driving with an active ATB enforcement, anything besides [BD] the enforced speed is 10x the value indicated by the Cab signal. e.g. [8] (Yellow) will enforce 80km/h, with the exception of [-] (Yellow) which will enforce 40km/h.

However, ATB allows an speed of +5km/h, so [8] would allow a speed of up to 85km/h.

When the train passes over the currently enforced speed (overspeed), an audible warning alarm will immediately sound to inform the driver that speed must be reduced. The driver will have approximately 3 seconds to apply the brake to a minimum amount, which will silence the alarm and prevent a forced brake application. Failure to apply enough brake within the time limit will incur a forced brake application bringing the train to a stop.

If brakes are appropriately applied within the time limit the train will be allowed to continue with that brake application until speed is reduced below the enforced limit. An audible notification (3 bells, buzzes, bleeps) will sound to inform the driver that the brake can now be released. This notification will sound when below the +5km/h excess speed, e.g. 85km/h under the [8] code.

When a forced brake has been applied there will be an indicator, cab desk light or display screen icon, to indicate the forced brake application is active.

If these steps are taken correctly, the forced brake application indicator will turn off, and the driver will be allowed to continue.

When ATB speed enforcement is reduced due to a code change, there is a delay before the warning alarm first sounds. This delay in the change of speed in the cab and outside is down to the delay in the equipment. This delay is random and differs per day and per train. After this delay, the behaviour is the same previously described.

When a speed enforcement changes an audible notification will sound to inform the driver of the change. This occurs for both an increase and decrease of speed. Assuming train is below the new speed after a reduction, this bell is a notification only and does not require any response from the driver.

The CODE trackside signage marks the ATB code changeover point. This is placed where ATB goes from ATB-EG into ATB-NG or the opposite.

When receiving the [BD] code, the train is no longer limited to any speed and an audible notification (5 bells, buzzes, bleeps) will sound to inform the driver. When this enforcement occurs, the train will ignore a 0/none code since the lack of a code could indicate the train is no longer in an ATB signalled area.

ATB - Vv (Improved Version) includes additional failsafe's to prevent trains from passing stop signals when under influence of [BD] and [-] (Yellow) codes.

Beacons are installed 120m, 30m, and 3m from select signals that communicate brake curves to the loco.

These magnets are not installed at every signal, they are only installed at select locations such as high traffic areas. These brake curves are not displayed or otherwise communicated to the driver in any form.

The onboard system will only respond to these magnets when [-] (Yellow) or [BD] codes are being enforced, and will not respond to the magnets at any other code.

If the train remains under the speed enforced by these brake curves, the onboard system will do nothing. If the train exceeds the speed enforced by the brake curve, a forced brake application is applied to bring the train to a complete stop.

Standard emergency recovery applies between the 120m and 30m magnets. After the 30m magnet the train will be further limited to 10km/h (+5km/h).

Some installations include a disarming loop installed from the signal and up to 60m away.

This disarming communicates to the train in a similar fashion to the Beacons, except it spans the range instead of being limited to specific points.

The disarming loops will notify the train when the signal aspect increase from stop, allowing the train to proceed at the 40km/h speed immediately without having to pass a beacon first.

This is a great improvement if the train has already passed the 30m beacon as it would otherwise be impossible to drive slow enough to remain under the brake curve which would incur an emergency stop.

When a new code not equal to either [-] (Yellow) or [BD] is received, the brake curve and reduced speed enforcements will be lifted immediately, allowing the train to drive to the speed indicated by the displayed code.

For more information on ATB in-game, head to the relevant Tutorial. You can find out more about the Spoorlijn Zwolle – Groningen route Add-on on Dovetail Live.

Powering the new ATB system is of course, a whole new set of signals to TSW, the Dutch colour light system. In many respects, they look exactly as one would expect modern signals to look, able to display green, yellow and red aspects, with absolute, distant and ground variants. Different aspects correspond to different ATB speeds, and speed reductions can also be accompanied with a lighted theatre that can display routing and additional speed information.

Should you wish to drive with ATB turned off, you can comfortably follow the colour lights, as per most routes in TSW, either by looking ahead or by using the HUD/track monitor.

Also aiding your way along the Dutch countryside is bespoke signs to look out for:

On most routes, it is purely up to driver knowledge and discretion how they brake for an upcoming station, and the same will always be true in adverse conditions, but a handy sign exists called a Verkenbord that advises drivers when they should start braking to comfortably make a stop from line speed.

Once approaching a station, look out for the stop markers distributed along the platform. These are measured using car lengths similar to those of the ICM, so the maths is straightforward, driving a 6-car Koploper? Stop at the 6-car or next highest available marker. The SNG is shorter per-car than the ICM, so a 6-car Sprinter would need to stop at the 5-car marker.

One key difference with Dutch OHLE is that it runs at 1.5kV DC, rather than the typical 15 or 25kV AC common across Germany. The lower DC voltages, combined with the speeds trains run at, generates much higher amperage than on typical OHLE, and the way the design compensates for this is by running double contact wires, increasing the surface area with the pantograph. This detail is represented throughout the length of the route.

Lastly, watch one of the many fantastic and insightful cab ride videos of the route in reality and there is an undeniable detail making a home on Dutch routes – bird nests! Storks are a protected species in the Netherlands, having nearly died out in the mid-20th century, but conservation efforts have thankfully kept this from happening. Perhaps what people wouldn’t expect though, is with their resurgence in the wake of mass electrification, Storks have taken it upon themselves to frequently nest atop the gantries of the NS railway network! As you drive throughout the route, take a moment to peek above the horizon and see nests scattered across the route.