What the Numbers Mean

All the route measurements are made using a measurement tape attached to the anchors at the top of the climb and run through carabiners attached to all bolts on the route. The tape is pulled tight and the anchor heights and bolt heights are measured. It is important to realize that the measurements are made on a given day and that at a later point in time, the route can change: bolts can be chopped, bolts can be moved, or anchors can be upgraded. Details of the hardware observed on the day of measurement are given and if the hardware found on the route on the day of climbing is different, then beware.

Climbers can demonstrate stange and eccentric behavior. Some climbers have very stronge views about how routes should be protected and often view routes as their own personal property. One day, hardware can be there, the next day an egotistical climber may come along and chop all the bolts. The measurements presented in this website are accurate on the day of measurement, however, they can and will change over time. If you observe changes in hardware on routes described in this web-site, let me know and I will change the description.

"Sport" Route

If a route is described as being a "Sport" route, it means that the route is routinely climbed with only quick-draws. It does not mean that the route is safe or that you will not be hurt if you take a spill. Since the gear placement is well known on "Sport" routes, estimates of the worst-case falls can be calculated. It is also possible to determine if there is a risk of hitting the ground. If you look at the "Bolt Tables" and think about the mathematics of the bolt heights for most sport routes, you will see that there is typically two regions where there is risk of hitting the ground:

"Traditional" Route

A "traditional" route is a route where there is no protection placed on the route. The climber is required to place all the gear and protect themselves as they see fit. The route may have anchors at the top for lowering, but all protection on the climb must be placed by the leader.

Since the leader places all the protection on a "traditional" route, the parameters of the "Bolt Table" are not relevant for these climbs and will not be given.

"Mixed" Route

A "mixed" route is a route where there are bolts on the route, but at least one region of the climb is run-out. Normally, protection is placed by the typical climber in this region. Some "mixed" routes will have only one run-out region requiring protection (one bolt away from a "sport" route). Some "mixed" routes will only have one bolt (one bolt away from a "traditional" route).

Since the leader must place some the protection on the route, it is impossible to make the "Fall Estimate", calculate the "Ground Margin", or determine the "Ground Risk". The "bolt number", "bolt heights", and "run-out" are included in the "Bolt Table" and these measurements can be used to determine regions that require protection and for informational purposes.

Bolt Number

It seems obvious to me, but I will go through it anyway to make sure that there is no confusion. All bolts in the "Bolt Tables" are referred to by bolt number. Bolt number 1 is the bolt closest to the ground. Bolt number 2 is the bolt second closest to the ground. This numbering scheme continues through all the bolts on the route. The anchors are usually above the highest bolt (the bolt with the biggest number) and represent the top of the climb.

Route Height

Measuring the route height begins at the anchors. The measuring tape is attached to the anchors and is run downward through carabiners attached to each bolt. The distance from the anchors to the ground directly beneath the first bolt is measured and called the route height. If the route is vertical, then the route height measurement is very close to the vertical distance from the chains to the ground. If the route traverses or the bolts zig-zag back and forth, then the route height measurement may be greater than the vertical distance from the ground to the chains. The important thing to keep in mind is that the height measurements are made by running the measurement tape through the bolts to the ground. It is not measured by attaching the tape to the chains and pulling the tape directly to the ground beneath the chains.

If the anchors at the top of the route are chains, then the measuring tape is attached to the second to the last link on the chains (the link next to the one that the rope runs through). If the anchors at the top of the route are cold-shuts or bolts, then the measurement tape is attached to these cold-shuts or bolts.

Bolt Height

As described in the previous section, the measurements are made by pulling the measurement tape tightly from the anchors through carabiners attached to each bolt. This means that the bolt height is the sum of the straight line distances from the ground through each lower bolt to the bolt in question. It is not the vertical distance of the bolt from the ground. If the route traverses or the bolts zig-zag back and forth, then the bolt height will be greater that the vertical distance from the ground to the bolt. For most routes, the bolt height is very close to the vertical distance of the bolt from the ground.


Run-out is the straight-line distance from one bolt to the next. On a "sport" route, the run-out is directly related to the distance you will fall. A large number for run-out means that there is a risk of significant injury if you fall. A small number for the run-out means the risk is much less. It is up to the climber to determine what is a "large run-out" and what is a "small run-out". If you are unsure as to what is "large" and what is "small", error on the side of being conservative.

On traditional or mixed routes (routes that typically require gear placement), the run-out measurements can be used to determine regions that require protection. Since the location of the protection is not as clearly defined on a traditional or mixed route, the "Bolt Tables" for these routes do not contain estimates of the maximum fall ("Fall Estimate"), estimates of the "Ground Margin", or the risk of hitting the ground ("Ground Risk").

Fall Estimate

The "Fall Estimate" is an attempt to estimate the maximum fall that is possible on any section of a sport route. The "Fall Estimate" is derived from the bolt and anchor height measurements and is defined as twice the run-out distance plus five feet (twice the distance between two bolts plus five feet). Twice the run-out distance represents the absolute minimum amount of rope that is free right before you clip the bolt. A factor of five is added as a guess as to the slack that is in the rope due to the belaying process, the way the rope is held by the draws, and the stretch in the rope during a fall. This factor of five is probably about right for the lower bolts but may be significantly higher for the upper bolts where there is potentially much more slack and stretch in the rope.

The risk of injury is directly to the "Fall Estimate". The higher the "Fall Estimate", the greater the chance of injury. If the "Fall Estimate" is high (indicating the potential for a large fall), then the climber should either use extreme caution in this area or should decide not to lead the route. As they say "...discretion is the better part of valor".

Ground Margin

The "Ground Margin" is used to estimate the distance between a climber and the ground if a fall occurs. It is simply defined as the bolt height minus the run-out to the next bolt. If the first bolt of a climb is 20' high and the second bolt is 30' high (a run-out of 10'), then the "Ground Margin" is 10' for the first bolt (20' - 10').

The risk of hitting the ground is directly to the "Ground Margin". - the smaller the "Ground Margin", the greater the chance of hitting the ground. If the "Ground Margin" is negative, then a fall could result in the climber hitting the ground without having the rope absorb any energy of the fall. If the "Ground Margin" is less than 10', there is still the chance of hitting the ground. This is due to slack in the rope, the dynamic stretch of the rope, and the length of the quick-draw that the rope is clipped into.

"Ground Margin" should be used to assess the risks on a climb and should be used to select or reject one climb over another. A difficult climb with a small "Ground Margin" should be avoided by beginner climbers. Advanced climbers with many years experience will easily be able to assess the risk with out consulting the numbers - for them, the "Ground Margin" is strictly informational.

Ground Risk

The "Ground Risk" is a Yes/No warning to indicate if there is a risk of hitting the ground. If the "Ground Margin" is less than 10', then there is a risk of hitting the ground and causing injury. The 10' threshold is set to account for slack in the rope, the dynamic stretch in the rope, and other intangibles. Although 10' may sound like a conservative number, it is probably too low.

Example: the first bolt on a climb is at 20' and the second bolt is at 30'. If a 6' climber stands below the second bolt, reaches up to clip the rope, and falls, will his feet hit the ground?

The "Ground Margin" is 10' and the "Fall Estimate" is 25'. With a 10' "Ground Margin" one might think the climber has plenty of room, however, this may not be the case. Here is the logic: There is 10' of rope out due to the run-out. There is approximately 4' of rope out from the climbers waist to his hand reaching out to clip the rope into the bolt. Thus, there is 14' of rope out above the first bolt. Without removing slack and accounting for rope stretch, when the climber falls, the climbers waist will be 6' off the ground (the height of the first bolt minus the rope out above the first bolt). Of course, his feet are hanging about 3' below his waist, putting his feet 3' above the ground. When rope stretch and slack are accounted for, it would be reasonable to expect that there would be more than 3' of stretch in a dynamic rope on a 25' fall and probably several feet of slack. The climber will probably hit the ground hard with very little of the energy in the fall being absorbed by the rope. I hope he doesn't get hurt...

The "Ground Risk" is a binary flag indicating potential problems on a climb. There are too many variables in a climb to determine a universal threshold for danger on a given route. The type of rope the climber uses, the length of the draws, the skill of the belayer, the height and length of the fall, are several factors that make estimation of the "Ground Risk" an art and not a science. These numbers should help a climber assess the risks associated with a given climb, however, the climber has to determine his/her own "danger threshold" - the risk they are willing to take to complete a climb. It is a personal decision.

As a final statement, it should be noted that there is always "Ground Risk" on any climb. The rope can break, a carabiner can fail, you can back-clip a draw, etc. Any number of gear failures or personal screw-ups can occur. That is why climbing is considered an "extreme" sport. The "Fall Estimate", "Ground Margin", or "Ground Risk" are numbers that can be used to assess risk given that your gear is in good condition and protection techniques are reasonable.

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Copyright ©: 2001, RAHutchins
Revised: March 23, 2001
Corrections/Comments: bob@climbaz.com
URL: http://www.climbaz.com