Creating an Emergency Location Marker System

What no one wants to see.

While mountain biking isn’t as likely to injure riders as some believe, the fact is, sometimes there are boo-boos on the trail.  And some of those boos-boos require the calling of emergency personnel.  How can land managers and clubs create a system to benefit those that need to call in emergency services?  What systems are the easiest for users and still work for those personnel?

​Let’s talk about an Emergency Location Marker (ELM) system.

​What is an Emergency Location Marker system?

​To put it in the simplest of terms, an ELM system is a way to tie a location in a public land to some form of marking.  This allows a person who needs some sort of assistance to mention a marking to an emergency services operator and then have the corresponding location of that marking passed onto the actual individuals of the emergency services.  Typically, these markings take the form of a sign with some sort of code or tag that is clearly visible to users.

Beyond that, the types of ELM markers and how they are laid out come in more flavors than Baskin Robbins ice cream.  Where trails are concerned, the number of different types is reduced, but still can be quite different based on region and trail differences.  A lot of the regional differences come from the relative in size and layout of the trails in question.  A large and expansive trail system in Pennsylvania, for instance, might be very small for Utah.  An ELM system that works in one might not work in the other.

But when it comes to urban mountain biking are there really that many different ways to create an ELM system?  We have to acknowledge that if your region has an ELM system that they currently use, this should be adapted to trails within an urban system.  Let’s not reinvent the wheel for the sake of reinventing the wheel.  However, many cities do not have an established ELM system, either due to never putting the effort in creating one or a lack of need in a public lands system that contains few trails.  If we, as mountain bikers in conjunction with the land manager, are creating an ELM system from the ground up, are there that many different systems that work for relatively small urban systems?  Honestly, no, there are basically 4 options.

​United States National Grid (USNG)

First, let’s talk about why the United States National Grid (USNG)   system for ELMs likely is not the best ELM system to use on a trail for urban areas.

The USNG is a 1km by 1km superimposed grid system with grid squares defined by their relative northing/easting values.  A point within that grid could have any decimal number along an axis (northing/easting) within the grid, such as 45.43, for instance.  If you are familiar with a military grid system, it’s the same principle.  

For most urban trails that use some from of stacked loop system, a 1km grid is massive in comparison to urban parks.  Many intersection points may fall within a single grid.  Take Roosevelt Park in the City of Dubuque, IA for instance.  It’s one the most amazing systems in Iowa with 10 miles of riding.  However, the total east-west length of the park is 0.83 kilometers and the part of the park that contains the trails is only 0.84 kilometers along the north-south length.  In other words, the entire park lays within one grid of the of the USNG.  (Actually, the USNG line break occurs almost down the center of the park, so technically it’s in two grid zones.)  The USNG ELM system uses a 4-digit place number (two digits for the grid number, two for the decimal length within the grid), along two axis, latitude/longitude, for an approximately 33’ grid.  The thing is, because of the way the USNG grid system works, the numbers for these grid locations are extremely similar, make misplacement to transcription errors more likely.  The USNG coordinates for the start of Lydia’s Meadow, a trail at Roosevelt Park, are 8665-0464 and the coordinates for end of the same trail are 8684-0479.  That means a total of 8 digits would have to be given by a person needing response to an operator, then passed to emergency services personnel without any transcription errors.

Dubuque on Trailforks.com

​This illustrates another issue of the USNG ELMs: the character salad problem.  A typical USNG sign has a 3-character alphanumeric code for zone, a two-character unique identifier and an 8-character latitude/longitude grid code.  Again, for reference the total code for the start of the aforementioned Lydia’s Meadow is 15T-XH-8665-0464.  For those playing the home game, that is a total of 13 characters to give a 911 operator as you are painting the trailside with your spurting blood.  If you are thinking that might be a bit hard to do or an operator could accidently type in a 5 instead of a 4, sending the ambulance a kilometer away, you would be right.

The three sizes of the USNG ELM signs.

The other issue is that the USNG ELM signs come in three sizes: 12×12, 12×9 & 6×9.  As you may have noticed, those are significantly larger than either the 4x4 posts or Carsonite signs typically used on trails for intersection and confirmation signs.  That means if you want to use the USNG ELM, prepare to pound in a lot of u-channel posts for mounting.  Also, the signs as designed for the USNG ELMS, while clear and easy to read, certainly stick out in a natural environment.  If you are wanting an immersive environment without a lot of sign pollution, then these are not the signs you are looking for.

It’s not as if the USNG ELM system is completely bogus.  Obviously, it would be recommended for trailhead locations and any main “hub” locations within a trail system.  But on-trail ELM markers using the USNG system currently have too many issues.
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But what if there was a way to make use of the upsides of the USNG grid, but make the ELM system way more user friendly for everyone?

​Imposed Number USNG

​The Imposed Number USNG basically retains all the back-end advantages of the USNG system and imposes on it a simpler method to identify the actual locations on the trail.  To understand how this works, let’s use this cartoon of a trail system to walk through what is going on here.

What a Imposed Number USNG system looks like in practice.

​The first thing you will notice is that the numbers on the trail system are only 2 digits in length, versus the 8 to 13 characters of a true USNG system.  All that is happening is that the points we want to identify, and starting at the southerly and most westerly point, working northward, then starting over easterly and southerly, working north again.  Like this:

Work from the SW to the NW back down to the south.

The advantages of this system become obvious when compared to a true USNG system: there are only 2 characters to remember and tell a 911 operator as the vulture’s circle.  Also a two-character system is easy to place on intersection and confirmation signs.  Additionally, because we are using the USNG system, all that is needed is to have these imposed character codes shown next to their respective USNG coordinates.  That can be done on the official trail map, such as in the corner, or, given enough room, next to the point itself.  The zone code and the unique identifier likely will be the same for all the points on the trail, so we don’t need to worry about that.

The Imposed Number USNG isn’t perfect.  It does put the onus on emergency personal to have the map with the imposed number and the corresponding USNG location.  Also, it does mean that the numbers will likely be in non-sequential order.  That isn’t a big deal, it just seems weird to bike past number 13 and then 24.
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USNG codes, whether the real sign type or an imposed number, are not the only way to do ELM markers.

​Sequential Numbering System

​The Sequential Numbering System is exactly what it sounds like.  Starting at a point on the trail (usually the main trailhead) every confirmation point or intersection is numbered along one trail at a time.  Usually, the numbers stay on a trail until the end of the trail.  The first trail from the first numbered trail then picks up the sequence and so on.  No numbers repeat themselves.  In practice it looks like this:

A Sequential ELM system in practice.

The advantage of the Sequential Numbering System is so obvious they almost don’t need to be discussed.  Essentially, each number tells you a location and a distance from the first number of a trail.  So, if the beginning of a trail is number 37 and your confirmation signs are at a half mile interval, ELM point 39 is a mile from the beginning of the trail.

The only downside to the Sequential Numbering System is for trails with a lot of loops or trails that split off from or merge onto other trails.  Taking a look at Roosevelt Park, using this type of system would require a lot of forethought as the loops come and go and merge with each other.
What about emergency personnel, how do they find injured persons?  The simple answer is that it would be possible to create a rescue map with the coordinates of the ELM markers, similar to the Imposed Number USNG.  The one nice thing about this system is that if a person called in being near marker 24, all the emergency services personnel would have to do is find the corresponding trail number in the same sequence on the map.  Because these numbers are sequential just following the next number would bring them to the person in question.
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There is another system based on where emergency services access the trails.

​Access Numbering System

​The Access Numbering System numbers the ELM markers based on their relative distances from access points.  Usually, these are in 3-digit code sets.  100-199 could be for one access point, 200-299 could be for another.  Typically, there is some attempt ensure that similar numbers aren’t too close together, like 239 and 329.  This all seems very confusing until you see it on a map:

An Access ELM system in practice.

The most obvious issue with this system is that it suffers from the same problems of the Imposed Number USNG in that the numbers are not always sequential.  While many times they would be, at some point along each trail, they might jump as the trail nears one access or another.  It also requires that the emergency personnel know which access is tied to that number set.  This can be solved by placing a sign at the entrance to trail heads that list the ELM locations available from that trail head.  Something like “Emergency Access 100-199”.
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The Access Numbering System seems to be made for locations with multiple access points and yet very few individual trails.  If you look at a system like Greenwood Park & Water Works Park in Des Moines, Iowa, this type of system feels like a good fit: two main trails with 6 access points.

Center Trails mountain biking trails

​What is right for your trail system?

Ultimately, only you know what is right for your trail system.  Its best to talk to the emergency services personnel in your area before deciding on a system for your trails.  Likely, this will not be a one shot and done project.  Its best to work out a system on paper multiple times before purchasing signage.
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Whatever system you end up with, always be the one doing the outreach to the emergency services in your area every year and make sure everyone understands how to get to and from the trails.  Use these yearly meetings to see what ideas they might have for better or simpler system.  Use them also to build relationships and contacts that will help everyone make your trails as safe as possible.