Thanks to these preventive safety measures, the bored tunnel is extremely safe. However, a calamity can never be ruled out with 100% certainty. And of course prevention is always better than the cure. Should anything go wrong, the consequences may be contained to a minimum.

A section of the safety scenario for the Green Heart Tunnel stipulates that, in case of an emergency stop inside the tunnel, all passengers must be able to reach the other, safe tunnel half-tube within 10 minutes. This objective is realised by means of 2.10 metres wide emergency exit doors at 150 metres intervals throughout the tunnel. These doors can be reached easily following the escape routes that run along both sides of the tracks. These routes are 1.50 metres wide and well lit, as are the emergency exits.

If a calamity occurs in a tunnel tube, all train traffic is stopped immediately. From that moment, it is impossible that a train enters a tunnel. As a result, the other tunnel tube can be entered safely. When passengers reach the safe tunnel tube, they must be able to reach the surface as soon as possible. For this reason, the tunnel has five emergency exits at surface level. 

Two of these exits are the tunnel entrances, the other three can be reached through escape shafts located at Bent, provincial highway N11, and at Achthoven. Because the escape routes are at two-kilometre intervals, the tunnel has signs pointing to the nearest exit. When the passengers reach the escape shaft, there are stairways leading to surface level. Because of the depth of the tunnel (30 metres), the staircases have several landings where people can catch their breath.

The above scenario for a great part assumes and even relies on passengers' ability to get themselves to safety. This is necessary, because it will always be some time before relief services can arrive at the place of the incident. In addition, a tunnel is hardly ideal in terms of accessibility. Experiences have shown that the period between the occurrence of a calamity and the arrival of emergency services is crucial for passengers.

The other part of the safety scenario focuses on allowing emergency services to control the calamity and help the passengers who are unable to help themselves as effectively as possible. In principle the emergency services bring their own materials, which is transported from both ends of the tunnel. Of course, the tunnel can be entered via the escape shafts.

Upon arrival at the escape shafts, the emergency services can descend to the tunnel in elevators. The shafts have communication panels giving relevant information about the calamity. Even though the relief workers bring their own materials, there are all sorts of materials present in the bored tunnel, such as stretchers and fire-extinguishing aids. In addition, the bored tunnel has water reservoir tanks, to make sure that there is always enough water to fight the fire.

As indicated above, all train traffic is halted in the event of a calamity. This safety system also activates the ventilation inside the tunnel. The ventilation system pushes the smoke in one direction. This allows the emergency workers to approach the train from a safe side, keeping the effects of smoke or heat to a minimum.