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Toward a complete SAR base map

Mapping in search and rescue is both a key part of a successful mission and a mess. Truly, it’s an absolute mess.

Ideally, everyone would be looking at the same map. The map would be complete — all area trails, roads, former roads, points of interest, etc. Whatever device is used by ground teams to view this map would be capable of relaying its position, track and waypoints back to the incident command post in real time. And whatever mapping is done at the ICP — search areas, clues, cell-phone forensics, assignments — would be relayed back to the field units in real time, too. Situational awareness would just ooze out of every device and flood the operation with efficiency and effectiveness.

That all seems simple enough, but it is not. For one thing, SAR teams deploy a few dozen or hundred times a year, depending on the group, and only a subset of those missions call for any serious mapping. We just don’t get good at it — or we haven’t yet, anyway.

Pick a platform. Any platform.

In the front country with cell service, our needs could be met by everyone using a team account on SARTopo, an ATAK server or ArgGIS Online. Each of these has its advantages, drawbacks and costs. SARTopo, its team functions and its mobile app get closest to meeting the requirements at minimal cost and learning curve, but it is not a true GIS capable of being fed new shapefiles as needed. ArcGIS provides the most flexibility and functionality, and a SAR template and utilities exist, but it can be pretty inaccessible to the person at the ICP doing mapping (and the SAR world is not exactly full of GIS pros). ATAK is feature-rich and can be fed a customized set of GIS layers, but it is Android hardware-specific for now.

Away from cell service, another set of limitations immediately arises. Garmin InReach devices are the best thing going for position reporting and messaging, though some teams use amateur-radio-based APRS to accomplish much the same thing without expensive subscriptions. InReach with a business account enables a couple of key features that do not exist in personal accounts: device-to-device position reporting and an ability to feed location data to another program (such as SARTopo); APRS can also perform these functions.

All of the technology choices aside, what literally provides the base of the whole thing is a good base map. Each of the above options has a somewhat suitable base map except ArcGIS, where the GIS tech needs to build one. But a full set of the ideal data for front- and backcountry SAR in any region of the U.S. is found in a variety of datasets from federal, state and local agencies. Each of the available maps gets close but currently misses the mark.

Can we at least agree on a map?

This brings me to the topic at hand. There’s no perfect and affordable technology available at present to meet every SAR need, but surely we can at least compile the layers of data from various agencies necessary to make a solid base map. Everyone has REST services posted, and these are easily added to an ArcGIS Pro map and symbolized, resulting in a base map. Right?

It’s actually harder than it should be. Let’s start with trails. They cross agency boundaries. They exist in cities, on private timber land, in national forests and in municipal parks. Far too many agencies own trails, and too many trails are not maintained or owned by any agency, to compile a comprehensive set of trail layer. Thankfully for my area of the country, the Northwest Trails data for Garmin devices is actually pretty close, but it is a private project and does not necessarily track trail creation, modifications and closures. I found that to be close enough and added some obvious newer trails from our county’s GIS.

Next, roads. This is far worse. SAR teams want to know about every road, from the highway and county roads needed to get to a scene to the forest road that was closed 40 years ago but might provide easier overland travel than crashing through the brush. State and local GIS departments provide the authoritative data on their road networks. Federal land-management agencies provide the data on park-service and forest-service roads, even roads that are now closed to motor vehicles. That just leaves all of those abandoned logging roads and some other gaps.

In this state, the Department of Natural Resources comes to the rescue to fill that gap. Unfortunately, they fill it like someone who’s never used expanding foam insulation from a can. City streets and forest roads with geometry slightly different from the authoritative sources are in the same layer as those all-important logging roads. The names of roads not under DNR’s authority are often incorrect and the remaining attributes nearly always woefully incomplete, offering little hope of filtering by owner.

What to do? I messed around with the data for a few days then just decided to keep the DNR roads I could not filter out without losing other key roads. I attempted to bury them below the authoritative roads, which worked only when the geometry matched.

Thorough road data in this section of the Olympic National Forest required both the correctly named road segments in the USFS data (white roads) and the underlying DNR road data (double dotted lines), which is visible along the right side of this map where its geometry differs from the USFS data.

Ugliness ensued. I can’t believe the best choice is to tolerate multiple overlapping layers attempting to show the same roads. But here is an illustration of why it’s so essential to show both. This is from the front country, a large swath of mostly private timberland adjacent to a residential community.

County roads are white with blue borders, private roads solid gray and logging roads again in double dotted lines.

Approximately half of those old logging roads are shown in SARTopo’s base map. Garmin’s Explore maps (part of the InReach system purchased with Delorme several years ago) show even fewer roads and are pretty much unrecognizable as the same swath of ground.

It’s a start.

The annoying artifacts of overlapping road networks aside, I managed so far to assemble a workable base map for SAR operations in this county. I included most of the same data from three surrounding counties, too, but subjected it to a bit less scrutiny. In addition to the Northwest Trails data, county roads and DNR roads, it includes state-park roads, National Park Service roads, U.S. Forest Service roads, parcel boundaries and owners, structures, contours, hillshade, tree canopy, water channels, water bodies, public-land boundaries and county boundaries.

It’s not incomplete, yet it is fairly unobtrusive and looks like a base map on top of which a mess of SAR data can be drawn. I would love to have some group knowledge mapped — the helicopter landing zones, radio-relay points, way trails and climbing routes we have used in the past.

And just like that, I notice that my new base map is missing a key trail — not a primary route, but one we need to know about. SARTopo has it. So does OpenStreetMap, another potential source of a thorough trails layer.

1 thought on “Toward a complete SAR base map

  1. Great read.
    I’ll stick with retirement.
    Good job, Matt!

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