One of the greatest challenges during operations in underground transport systems (UTS) is the transport of persons who are unable to escape over long distances. Without any transport aids, the emergency personnel can quickly reach the limits of their physical capabilities. Which equipment is best suited depends on the specific task as well as the type and design of the respective UTS. The following article provides guidance on how the question of the most suitable transport aids can be clarified in preparation for operations.
The longer the approach, the more strenuous the rescue of persons becomes
The tunnel carrier's safety concepts for traffic tunnels stipulate self-rescue as the primary rescue measure. Firefighters support self-rescue by showing people who can flee the way or leading them out of the dangerous areas. However, immobile persons such as injured or disabled persons must be moved to safe areas by firefighters. Over longer distances, however, it is hardly achievable to simply carry a person. With every metre, the person to be rescued feels heavier and heavier. Without transport aids, firefighters quickly reach their performance limits when carrying immobile persons - especially when wearing breathing apparatuses.
Reference scenario: Rescuing a person from the smoke
In the following, the task of rescuing a person, unable to walk, from a smoke-filled area of a road or railway tunnel by bringing them to the nearest emergency exit is considered. In road and railway tunnels, according to current regulations, the distance to be covered can be 300 to 500 m, in older railway tunnels several kilometres. The onward transport of the persons on the safe side of the emergency exit is not taken into account here.
Simplest solution: dragging
The general solution to the transport problem arises from physics: You give some of the person's weight to the floor. The simplest version is to drag the person across the floor. Webbing slings can help hold the person better and improve not to slip off clothing and limbs. However, if the person to be rescued is dragged over the floor and sharp edges, they may suffer injuries. Tests conducted by the International Fire Academy showed that even robust fire protective clothing was scoured down to the skin of the «test comrade» after dragging it over a rough concrete floor for about 50 metres. Dragging over distances of several hundred meters is therefore not compatible with the principles of patient-friendly rescue.
Therefore, a protection between the person and the floor is pushed, for example, in the form of a basket stretcher. This aid can be carried or dragged across the floor. If used correctly (head of the person upwards, securing with straps, etc.), injuries to the person being transported can be largely ruled out. But: the longer and rougher the path, the more the basket stretcher will be worn. In an emergency, this can be accepted. In the daily training operations of the International Fire Academy, there was a risk of cost-intensive wear and tear on the basket stretchers.
Wheeling instead of dragging
After the switch to basket stretchers with wheels, it quickly became apparent in our training operations that these have other advantages in addition to being better for the material: The rolling resistance is lower than the dragging resistance; less force has to be used. Thanks to wheels, the stretcher swings less side to side than before; it can be manoeuvred more precisely, given a little practice. However, rolling can be more difficult on uneven surfaces such as track ballast. Then, the basket stretcher is not rolled, but simply dragged over the ballast.
For corners and edges: transfer cloth and half-drag-stretcher
A disadvantage of basket stretchers: They are rigid and relatively long. It is impossible to get around tight corners with a basket stretcher, as is the case in passenger coaches, for example. In tight spaces, soft stretcher and half-drag-stretchers have proven their worth, at least in training. In half-drag-stretchers, the person to be rescued is partly dragged across the floor and partly carried. They are less comfortable for the persons to be rescued than basket stretchers, which also protect patients better. But instead, soft stretchers and half-drag-stretcher offer the firefighters more flexibility in confined spaces.
No aid is suitable for every situation
As shown before, transport aids are not equally well suited for all situations. In road tunnels, basket stretchers with wheels and half-drag-stretchers practically always prove to be helpful and largely problem-free to use. For rescue from narrow passenger carriages, in most railway tunnels, a combination of basket stretchers with wheels for use outside the trains and soft stretchers inside the trains is likely to be effective.
Choice of aids is the task of operational preparation
The choice of the right transport aids also depends on the specific nature of the escape routes of the UTS. Not every tunnel system offers easily passable rescue routes according to the standard. For example, there are escape routes from urban railway tunnels that end «somewhere» in buildings, in a concrete case study, surprisingly in a large laundry.
It is therefore recommended to walk all escape routes of a UTS and to check whether narrow doors, winding corridors, steep staircases, narrow passages and the like constitute insurmountable obstacles, e.g. for basket stretchers. Ideally, appropriate tests are carried out, which can be combined with a training drill on-site. These should be feasible for many areas of a UTS, of course in consultation with the operator, without stopping traffic. As there are hardly any obstacles to be expected in the tubes with traffic of road tunnels or railway tunnels, the drill can be limited to the escape and rescue routes outside these areas. Often the problems show up at the end of these paths, such as doors or stairs.
What, how many and where?
Once the transport aids suitable for your UTS have been found, the question arises as to the number required. The above-mentioned transport aids are only suitable for the rescue of individual persons. The decisive factor for procurement is, therefore, not how many people may have to be rescued, but rather how many search & rescue teams are to be equipped with the transport aids in the initial phase of the operation. It must then also be clarified where the transport aids will be stored. Some fire services deposit them in a suitable place in the UTS itself, others in the fire station to load them onto the vehicles when an alarm for the tunnel is received.
For the transport of a larger number of people out of a dangerous area in an UTS, only one fire service-specific means of transport is known in Switzerland: the firefighting and rescue trains (FRT). Its rescue car is positive pressure ventilated out of air cylinders and protects people from smoke. Depending on the type, it can take up to 80 people and drive out of a railway tunnel.
Practice, practice, practice - also with a fun factor
Whether with or without wheels, whether soft or basket stretcher: Especially the transport of persons should be practised intensively - ideally with role reversal: Anyone who has ever been rescued in a basket stretcher knows from their own experience how to handle the transport aid in a way that is gentle on the patient. Practising patient transport is usually associated with a certain amount of fun. The benefits go beyond UTS operations. For example, the transport of a heavy person through steep, difficult terrain is often only possible with a suitable and well-controlled transport aid.