Lead Rope Solo – a draft for a risk assessment

From about 20m of vertical distance from the anchor, the rope weight in the system begins to pull additional rope through the belay device. This can form a rope loop at the anchor, which can be several metres large. If there is no visual contact with the anchor or the climber is inattentive, the potential fall distance is increased by this amount of rope. If the climber is above a ledge or in stepped terrain, this additional rope can cause a collision with an obstacle or at least an unplanned long fall in the event of a fall. Fractures of extremities, ligament and tendon injuries, or more severe injuries can be the result. The rope slack can also cause the rope to deviate from its intended path and catch on sharp structures. In the event of a fall, this can lead to rope damage up to the point of breakage, resulting in a potentially fatal fall. Without appropriate countermeasures, the likelihood of a rope loop forming is very high. Therefore, the probability of occurrence and the extent of damage are significant, making the risk very high.

Counter measures:
The rope can be fixed in the intermediate protections with a clove hitch or Italian hitch. Advantage: no additional equipment needed. Disadvantage: Using a clove hitch can increase the impact force.

Alternatively, the rope can be prevented from backfeeding using an elastic prusik. Advantage: self-made, reliable. Disadvantage: Complicated to attach with one hand.

Elastic loops pulled over the carabiners and then onto the rope after clipping also prevent backfeeding. Advantage: easy to use, small and light, can be self-tied. Disadvantage: they do not hold the rope infinitely strong, wind or excessive rope weight can overcome the clamping effect.

Some small retailers offer special carabiner inserts for sale online. Advantage: very easy to use and reliable. Disadvantage: must be bought or printed at home.

Residual risk:
All these measures are highly effective. When used correctly, the probability of a rope loop forming can be reduced to zero. Therefore, the risk with the use of reduction measures is very low.

In partner belaying, the belay device is usually attached to the belayer's harness. In the event of a fall, many components of the belay chain absorb part of the fall energy: the rope stretches, rope runs through the system, friction on carabiners and all surfaces converts energy into heat, harnesses compress, and the bodies of the individuals convert energy into deformation.

A significant factor is the acceleration of the belayer towards the fall load. In an LRS system, the end of the rope is attached to an anchor point, and the rope runs through the belay device on the climber's harness. Thus, a significant energy-absorbing element, the belayer's acceleration, is missing. The later in a pitch the LRS climber falls, the more rope is in the system, the smaller the fall factor (fall height divided by the length of rope paid out), and the more energy the rope can absorb. With 25m or more of rope in the system, even a longer fall of several metres feels hardly different from a typical sport climbing fall.

Near the anchor, however, and especially before clipping the first intermediate protection (in a multi-pitch route), the fall factor is very high, the rope can absorb little energy, and the fall will be very hard. In unfavourable fall positions (sideways, backwards, headfirst, etc.), an impact force from about 4kN (depending on the climber's weight) can cause severe internal injuries and spinal injuries. Near the anchor, the probability of this effect must be set to 1. Therefore, the risk is initially assessed as extremely high.

We have conducted several tests where the distance to the anchor, the amount of rope in the system, the belaying method, and the belay device were varied. As expected, the impact forces were highest with little rope in the system, low-friction situations without redirections in the intermediate protections, and a semi-automatic belay device without rope feed.

With 10m of rope, 6m of free fall, an 80kg person, and the rope fixed at both the anchor and the climber, we measured impact forces of just under 4kN on the falling person. In the worst-case scenario, the factor-2 fall into the anchor, however, a frequent additional effect occurs: Many of the semi-automatic belay devices used for LRS today have what feels like a blocking function. In the force ranges of everyday loads, this consideration is correct. In the force ranges that occur during the described factor-2 fall, however, most devices allow rope to slip through.

The slippage value depends on the device, the rope diameter, and the rope condition and cannot be generalized. With different ropes, we have conducted tests with a PINCH and measured slippage values between 5 and 6kN. These forces would immediately act on the falling person's body in a real scenario and could cause injuries due to the high acceleration, depending on the fall position and body tension. The risk is therefore still considered high.

Counter measures:
A possible reduction measure for this problem is the use of shock absorber slings, so-called screamers. To maintain a fully functional belay chain, the use of screamers with a residual breaking strength of 22kN is required. Initially, a first screamer can be placed between the end of the rope and the anchor point. Even in the factor-2 fall, this shock absorbing device could convert a large portion of the fall energy and reduce the force in the system to the tear value of the device. Placing a screamer in intermediate protections also reduces the impact force and the force acting on the intermediate protection, thus reducing the likelihood of insecure intermediate protection failing. Later in the pitch, screamers can be omitted as there is now enough rope in the system to absorb the energy.

In addition, other damping elements are used today to reduce the impact shocks in an LRS system. Even threaded via ferrata friction brakes, deflections, elastic band packages... However, these measures are difficult to quantify and evaluate and have therefore been omitted from this evaluation. As long as a fully-fledged safety system is used in parallel without restriction, the following applies to most of these measures: Even if it may not help, it probably does little harm.

Residual risk:
Depending on how many screamers are used and what their tear values are, the force in the event of a fall can be reduced to an extent similar to that of normal sport climbing falls. Therefore, the remaining residual risk is comparable to that of a normal to hard sport climbing fall.

The issue with belay devices can be explained by the following circumstance:

Typically, belay devices certified according to the European Standard 15151-1 are used for LRS today. These devices are usually referred to as semi-automatic devices on the market. However, the title of the standard is "Manual Braking Devices with Assisted Locking."

So, YES – the devices can block/lock the rope, but this requires manual assistance. In the usual partner belay process, this corresponds to the brake hand. The brake hand holds the rope and thus activates the locking mechanism. In the passive test of the standard – where the device is attached to a fixed point and a fall mass falls directly into the device in a 2m factor-2 fall – this activation is simulated by 2m of rope weight on the brake side. Additionally, in this scenario, the impulse on the device is quite high, and the locking mechanism is quickly activated by the static friction of the rope on the camming mechanism.

In an LRS setup, often all three favourable factors are missing:

There is no brake hand on the rope, falls can occur directly or shortly after clipping the bolt high up, resulting in a very low impulse on the device, the rope can run through the device, static friction transitions to sliding friction, and the mechanism is not activated, and finally, the weight of the rope on the brake side is missing because the cache loop contains the brake rope and this moves downward with the falling person due to gravity, so it is weightless at the moment of the fall.

Additionally, the devices are often modified by users to better secure the device and facilitate rope feeding. At this point, the manufacturers of the devices are no longer liable for accidents resulting from device malfunctions. All manufacturers of these devices explicitly require the brake hand principle in their instructions, which cannot be met in LRS. Moreover, manufacturers exclude liability for unauthorised structural modifications to their devices.

We have conducted a series of tests on the use of braking devices according to EN 15151-1 in LRS, demonstrating that in the worst-case scenario—near the last bolt or immediately after clipping the bolt, with a medium-sized cache loop (about 1-3m of rope)—the entire length of the cache loop is typically pulled into the device until the minimal resistance of the cache loop attachment provides the necessary resistance to activate the camming mechanism.

Specifically, near the anchor, where the impulse on the braking rope in the device is low, one must expect a fall distance up to the end of the cache loop.

Counter measures:
Simply being aware of this risk can already be a countermeasure, as the climber can adapt their behavior in areas and situations of increased risk, for example by adopting a more defensive climbing style.

Especially above ledges or situations where there is a risk of impact, it makes sense to prepare several smaller cacheloops or to keep one cacheloop small in order to keep the rope run-through as low as possible in the event of a fall and failure to activate the device's clamping mechanism. Regular stop knots in the rope limit the fall distance beyond the safety of the cacheloops.

Residual risk:
Although the residual risk can be reduced by these measures, in terms of a realistic climbing flow, larger cacheloops will always be required and the risk of a further fall with possible injuries from impact or collision cannot be completely ruled out.

Note: In the course of the investigations for this publication, various device-rope combinations available on the market were tested and it was found that combinations exist which, although they comply with the approved standards, can cause severe rope damage and even rope breakage in the device in the extreme case of a factor 2 fall. A clear function of the combination used can only be determined by suitable tests or by consulting the manufacturers.

Both in team climbing and in LRS, the belay device must be attached to the harness, so what is the difference?

In team climbing, the belay device is attached to the belayer's harness. Even in long and hard falls, typically less than a third of the force applied to the falling person reaches the belayer due to friction in the belay chain. In LRS, the force is directly on the device attached to the falling person's harness. The forces can therefore be significantly higher. Even in hard fall scenarios, forces between 2 and 3kN are standard on the belayer.

In a hard LRS scenario, depending on the fall factor and the device's slip value, forces around 6kN are conceivable. What is the problem?

The carabiners used to attach the device to the harness can be unfavourably loaded. The most obvious unfavourable load would be lateral loading, and the European standard requires a residual strength of at least 7 kN for this load direction. A value close to the force that can actually occur here.

Even more critical are lever loads if the device is unfavourably positioned on the carabiner's locking mechanism. In a team climbing scenario, the belayer can monitor, detect, and counteract this during belaying.

In LRS, the person is usually 100% focused on climbing, and an unfavourable carabiner load could lead to complete system failure, resulting in a fall to the end of the rope. The risk is considered very high unless the device attachment to the harness can withstand all possible loads.

Counter measures:
Effective countermeasures are therefore all measures that ensure the device cannot detach from the harness.

This can mean using a connector that provides sufficient strength even in all unfavourable situations, such as carabiners certified according to American ANSI standards. This standard requires sufficiently high strengths even under lateral and unfavourable gate loads.

Alternatively, and significantly lighter, is a Maillon Rapide with a positioning and locking element, or, as possible with the Pinch, a direct attachment of the device to the harness with additional backup by a gear carabiner, completely eliminating the risk component of the carabiner.

SafeBiners with device positioning in the carabiner also provide a secure attachment depending on the geometry and function of the lock.

Residual risk:
These measures are suitable to reduce the residual risk of harness attachment failure to zero.

In team climbing, the rope end is tied to the climber's harness, creating a textile-to-textile connection. Unfavourable loads, self-unclipping, and lateral loads are generally excluded. Attaching the rope to a fixed point or anchor usually requires the use of carabiners or other metallic components. As with device attachment, unfavourable loads can occur here. A typical and perhaps the most unfavourable load case is a locking carabiner in a rigid bolt hanger. If the rope loosens, the carabiner can tilt sideways in the hanger. Upon reloading, the carabiner gate can press against the upper bar of the hanger, and the gate locking mechanism can be broken by loads as low as body weight, causing the carabiner to unclip. A potentially fatal fall would be the inevitable result. The risk is therefore considered very high.

Counter measures:
Possible countermeasures are all setups that make detaching the rope from the anchor point impossible. Examples of such attachments include:

Directly tying the rope into the anchor point and all types of pure soft links. This is in any case the safest attachment with reliable anchor points with sufficient eye radius.

With bolt hangers, the small radius of the hanger can mean lower strength of the directly tied rope. The reduced strength, however, is still significantly greater than the strength of an unfavourably loaded carabiner. Rope damage from hard falls can be reduced by interposing a three- or four-fold looped 120cm sling.

As with device attachment, a Maillon Rapide with a positioning and locking element is an adequate means for rope attachment. The same applies to ANSI-certified carabiners, although they are often significantly heavier.

A SafeBiner or locking carabiner with positioning device does not provide a safety gain here, as the stamping loads on the gate can occur equally.

With multiple anchor points, a cold redundancy, i.e., an unloaded series connection, using the previously described attachment solutions is recommended.

If available, sufficiently thick and healthy trees, directly tied with the rope, also provide a safe rope attachment.

Residual risk:
All the measures described are suitable for reducing the risk of the rope unintentionally detaching from the attachment point to zero.

If the leading person in a team is incapacitated and hanging in the rope, they can usually be lowered to the ground or back to the anchor by the belayer. In more complex situations in multi-pitch routes, improvised rescue procedures are available. In almost all cases, the team partner is at least able to initiate an external, professional rescue chain. A person who, for example, injures both hands in a collision during an LRS fall and can no longer rappel down by themselves will require a non-trivial rescue procedure even in the protected environment of a climbing gym. Whether these procedures and people capable of performing them are always available is at least questionable and should be thought out and planned in advance.

Counter measures and residual risk: see 1.