# Emergency Location Markers (ELM) on Trails



## flangehead (Feb 16, 2015)

I'm working on the development of a trail in the Houston TX area. Since it will be remote from street addresses, I'd like to install markers so that, in the event of an incident, a call to 911 can bring emergency services directly to the site. In my travels, I have not seen an emergency location marker on any Houston area trails. Though an urban area, there are large stretches of trail that are miles from a road or street (often due to creek crossings).


The research I've done so far indicates there are local systems (like the green Dallas Parks sign below) and the US National Grid system (blue signs below). I'm checking with local EMS and 911 systems to see if they recognize the national grid coordinates.


I'd appreciate comments from those who have worked directly with the advocacy and development of ELM in other areas. Specifically, any feedback on the choice between a local system (e.g. Dallas) versus the US National Grid system versus other?? would be very helpful at this stage. Also, experience working through the issues in an area with a large number of overlapping jurisdictions (we have cities, counties, precincts, MUDs, drainage districts..) will apply directly to my effort. 


Thanks!


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## life behind bars (May 24, 2014)

Longitude/latitude are universally recognized.


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## CycleKrieg (Dec 19, 2013)

Attached is a link to my local trail system's map. It has the location and GPS coordinates for ELM locations.

We use a yellow/black sticker callouts on Carnsonite.

https://files.dnr.state.mn.us/maps/state_parks/sra00302.pdf


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## HypNoTic (Jan 30, 2007)

ELM is dependent on your Emergency Plan and how local services will handle the call. Most resort I work with have their own patrol/first aid so calls to 911 are redirected to them (during business hours) so they can handle the situation accordingly. ELM are typically a letter/number related to the closest junction of two trails or a mile marker / access point on longer trails. Most of our emergency plan are based on that.


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## sunderland56 (Aug 27, 2009)

Why not get in touch with your local emergency personnel and ask them what would be best - i.e. what they would prefer? Best system in the world won't help if the 911 dispatcher isn't used to it.

I'd also keep in mind that a seriously injured person - or a panicked riding buddy - may not be able to read long strings of numbers off accurately. Anything like QR codes is also a bad idea (requires working cell phone and coverage, and is trivially easy to hack).


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## Surestick Malone (Jan 24, 2004)

Any 911 call from a GPS equipped cell phone should automatically report its coordinates as part of the call. This information is communicated to first responders when they are dispatched.
The only time this seems to fail is if the GPS is turned off or the phone was powered off just prior to making the call and the GPS didn't have time to calculate its position. 

I'd imagine, unless you're putting markers every hundred feet or so the likelyhood would be that a collision would happen out of sight of any markers. The money for the markers may be better spent elsewhere?


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## ACree (Sep 8, 2004)

The recently opened Raging River trail system in WA state has coordinates on signs when crossing roads. AFAIK, first responders in the area are typically the fire department from the local city (the trail system lies on state forest land just outside city limits of a smallish town). You might be able to get more information on how/why they determined what type of coordinates to use on the signage from Evergreen Mountain Bike Alliance. evergreenmtb.org


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## TrailYoda (Feb 23, 2009)

*Emergency Location Markers (ELM) on Trails.*

We have had a pretty good ELM system on our trails for quite a few years. With today's phone's all having GPS locations transmitted the need for ELM's is not as critical as in years past. I do think they still have a lot value as both way finder signing and rescue information.

I would recommend you have a meeting with both the Land manager and the fire captain responsible for the area where the trails are located.

The signing is something that will potentially need to be maintained after a 5 year period (depending on what signing materials you actually utilize.) Since all of our trails were on woodland areas our ELM signs were mounted on trees, this made it easier to post 30 miles of signs. However, over time and numerous ice and thunderstorms they do get damaged.

We have signs posted at .25 mile intervals. The GPS lat/long's for each ELM are on file with the fire department emergency responders. Evacuations for many of the trails are most effectively done using the lake and a boat to ambulance combination.

Here is what our 9"x 9" signs look like.

One of our trails was recently had replacement signs put up that are smaller. On a bike they are not noticeable which I think defeats the benefit of doing it.


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## mtnrsq (Jun 21, 2013)

I'm curious what the OP finally used marker-wise. 

Access for emergencies in my local SoCal area is easy enough based on trail name info plus approx distance. We can easily plan based on that info since there are no real intermediate points of access. Cellular 911 data helps narrow things down but, due to coverage issues, the call often originates from a spot some distance from the accident site. Standard latitude/longitude can easily be converted to any coordinate system we need, but people often miss or transpose digits. We had a MTB over the side call a couple weeks ago where the initial coordinates provided by a bystander put the location in South Korea when it was first plotted... Rider went about 15' over the side. Bike went another 40'+ and we still haven't found where it landed.


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## Jelf (Jun 26, 2010)

Surestick Malone said:


> Any 911 call from a GPS equipped cell phone should automatically report its coordinates as part of the call. This information is communicated to first responders when they are dispatched. The only time this seems to fail is if the GPS is turned off or the phone was powered off just prior to making the call and the GPS didn't have time to calculate its position.


A friend who is a first responder and a leading authority on USNG ELMs called my attention to this thread. *No, as a general rule cell phones do not automatically send coordinates to 911.*

Most cell phones produced since 2011 get data from both USA satellites (GPS) and Russian satellites (GLONASS). The FCC prohibits use of Russian data for the purpose of 911.

The wireless carrier handling a 911 call always delivers "phase 1" coordinates to the 911 call center. This is the location of the cell tower carrying the call. You with your bent bike and busted leg are some miles away from that tower.

The carrier *might* determine "phase 2" coordinates and put them into a database where the 911 call taker can access them. Phase 2 coordinates are determined as follows. Your phone sends the raw data from only the USA satellites to a black box on the cell tower. That black box processes the USA-only raw data and determines - if possible - the phase 2 coordinates.

*In short, the FCC requires that phase 2 coordinates be 'dumbed down' compared to the coordinates produced by your phone which uses both USA and Russian satellites.* More satellites = more data = better accuracy.

Wait - it gets worse. The FCC allows carriers broad discretion to exempt themselves from the requires to provide phase 2 coordinates. And if you are in heavy forest or a canyon there might not be enough USA satellites visible to your phone to determine any phase 2 coordinates. Meanwhile your phone can determine coordinates with good accuracy without any trouble since it can see enough USA + Russian satellites.

What does this all mean?

Everyone needs some way to know (1) their latitude longitude in decimal degrees and (2) the accuracy value for those coordinates. Use whatever works best for you. *But use something instead of nothing. *

If you cannot give 911 a good street address then you need to be able to give them coordinates in decimal degrees and the accuracy value.

For some tips on calling 911 with a cell phone (do you know the 17 second rule?) you can open up my map software and click *Menu ==> Tips for calling 911.*
https://mappingsupport.com/p2/gissurfer.php

And regarding ELMs, here is a story out of northern Minnesota where a skier was saved by a USNG ELM sign.

https://www.3m.com/3M/en_US/particl...?storyid=8b8c4802-cb27-49b5-b459-afddf7f98277

US National Grid (USNG) is the same as Military Grid Reference System (MGRS). The only difference is that USNG is written with spaces so it is easier to read. Since many first responders previously served in the army or marines, that already know USNG.

The federal government is behind USNG since FEMA has adopted it for ground operations.
https://mappingsupport.com/p/sar/FEMA_USNG_Directive_Final_10_15_2015.pdf

Anyone trained in MGRS/USNG can go anywhere and immediately use that system. By contrast, the 'bingo grid' (see green sign posted by OP) for a park at town A is different than the bingo grid produced for a park at town B, etc.

For more on USNG please see https://usngcenter.org/stateusng-maps/. I just traded email with those folks. They are in the process of rolling out new info regarding USNG ELM signs and then will update their website. If any of their links do not work, this is the reason.


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## mtnrsq (Jun 21, 2013)

Jelf said:


> .<snip> ......Everyone needs some way to know (1) their latitude longitude in decimal degrees and (2) the accuracy value for those coordinates. Use whatever works best for you. *But use something instead of nothing. *
> 
> If you cannot give 911 a good street address then you need to be able to give them coordinates in decimal degrees and the accuracy value.
> 
> ...


This write-up on E9-1-1 and phase 1 or 2 location functions.

Bottom line - some recognized reference coordinate is helpful. Decimal degrees/DD (e.g., 34.123456, 111.123456) is great and very helpful for any emergency response. Simpler than trying to give degree/minute/second info over a poor cell connection.

USNG (Universal Transverse Mercator/UTM which underpins USNG) is great for signs, but is much less likely to be something the average person can provide to a 911 call taker or have available beyond the sign. Regardless of format, most SAR/FD/EMS responders can convert to a preferred format to, for instance, guide a helicopter to your location. A universal coordinate system like USNG/UTM (or lat /long) is the gold standard. Do not use unofficial trail references since they may not be widely known or there may be two (or more) First Water Trails in a jurisdiction.

Unlike FCC rules on cellular 911, personal locator beacons (PLBs) make use of US, Russian, Indian and other satellites to gather location info. PLBs also do not require access to the cellular network.


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## cxagent (Dec 30, 2005)

Our MTB club has been and is still working thru this. Here is what we have found -

You need a unique location marker that is acceptable to the land manager and the local emergency responders (fire dept, EMS, etc.). That means that each trail is likely to be different due to preferences of those decision makers. And worse, as those decision makers change, they new person may want to redo everything their predecessor did. Regardless, everybody needs to have a consistent map showing those locations. This problem is compounded when a trail passes thru multiple jurisdictions.

What has worked - 
Zone systems are typically 3 or 4 digit locations that show exactly where the injured person is on the trail to the nearest 1/4 mile. We typically have the first one or two digits indicated where the first responder should enter the trail. The last digits indicated where on the trail within that zone. Some LO hate this system because the numbers are rarely sequential. It is not unusual to have say 502 near 214. That seems to drive some LO's nuts. The numbers might be sequential if the trail is linear. But with many trails in a trail system and markers at each intersection, don't expect 'linear numbering'.

Grid systems like on most maps. Usually there are letters on one axis (horizontal or vertical) and numbers on the other axis. This works fine as long as there are not many trails close by that don't connect easily. For example, there may be a trail at the top of a ridge (Porcupine Rim) and a trail nearby at the bottom (Castle Valley). Looking at a non-topographical map it appears those two trails are close. But they are separated by hundreds of feet vertically. Waterways or swamps could also create a barrier.

What has NOT WORKED -

Using GPS or Lat/Long as a location marker. Put yourself in the position of being concussed or in shock due to a broken leg. Do you think you can read and tell someone over the phone two 8+ digit numbers without error? What about when the different "standards" such as negative numbers or degrees/minutes/seconds are thrown in? It is a universal location marking but unusable for people in an emergency.

Mile markers - In an emergency people will report the "mileage" shown on their GPS or Strava instead of a sign post mile marker. Assuming they started at the same point, never doubled back, there have been no trail reroutes, etc. that should be accurate. But it is more error prone than the Lat/Long in an emergency situation.

Inconsistent maps - Did I mention that some LO's hate the zone numbers. So they change the map to not show the location numbers. Pretty soon, nobody can find the maps that shown the zone numbers. Or the LO decides that the public does not need those locations. If EVERYBODY is not working off the same locations shown on consistent maps - the whole location system falls apart.

I would like to hear other people's experiences.


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## CycleKrieg (Dec 19, 2013)

Did you look at the map link I posted before?

https://files.dnr.state.mn.us/maps/state_parks/sra00302.pdf

We use a pseudo grid system, west to east, with markers every one-half mile along the trail with a 2 digit code. The markers have known lat/long location that is shown on the map. It works out very well. If a person calls in and says they are near #47, its easy to tie that to a location. These are backed up with lettered "entry point" codes. That is for the rescurers. They can look at a map see the closest entry point to 47 is H.

As to land manager issues, here would be my suggestion: don't let them do this. You, the local club, establish a system and bring it to them. Be proactive and positive. If they have workable tweaks that don't jack things up, fine, if not, be nice but say "no". Also, you should issue maps every year, whether there are changes or not. Those maps should go to police, ambulance, etc. This also allows your club to have personal contact with these units of government. Its a chance to be a good neighbor and show your club as the adults in the room.

If I was to change our system any, I would add an area prefix. So our Mahnomen Unit numbers would be M01 to M54. Our Pennington Unit would be P55 to P59. You get the idea.


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## cxagent (Dec 30, 2005)

No I had not looked at your maps. I have now. I especially like the location numbering to Lat/Long on the map. That solves many of the issues.

I like your suggestions. Still thinking about how to implement them. Especially how to tell the land managers "No". That may create some problems even if it is the right answer.


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