As a part of a joint effort between the Town of Silverthorne and the Summit Sky Ranch development, Allpoints GIS and Contour Logic were contracted to provide trail planning services on private and National Forest lands. Several variables presented challenges that required detailed planning work. Lidar data analysis, 3D web scenes, survey data, high resolution web maps, and ArcGIS Collector in the field were all employed in a joint desktop and field GIS effort to create trail plans. I will detail our GIS methods and products from this project from start to finish.

1. The Making of a Trail:
Desktop and field GIS deployed to plan for new trails in Silverthorne
September 20, 2018 | GIS in the Rockies Conference | Denver, CO
Nick Viau Allpoints GIS

2. Collaborators

3. Quick Intro
Nick Viau | GIS Specialist & Instructor | Allpoints GIS

4. The Setup
✓ New housing
development being
built in Silverthorne
✓ Summit Sky Ranch /
Maryland Creek
Ranch

5. The Setup
✓ Development
agreement with
town calls for
developer to
build new,
public use
trails and park

6. The Setup
✓ Members of the
Silverthorne Parks,
Open Space, Rec, and
Trails Committee
contacted me and asked
for some mapping help
✓ Special thanks to John Taylor, longtime advocate of
outdoor recreation enhancement in Silverthorne.
Without his passion and tireless commitment, this
would never have happened

7. Reconnaissance
✓ First task:
Exploratory / recon
hike along proposed
MC trail corridor
✓ August, 22, 2017
✓ I took pictures with
my phone along the
hike (and made sure
the geo-tag setting
was turned on!)

8. Reconnaissance
✓ Geo-tagged photos to
points tool in
ArcToolbox brings the
photos into GIS.
✓ Data Management
Tools >> Photos
✓ Output is point FC in
a GDB with photos as
feature class
attachments

9. Reconnaissance
✓ Using ArcGIS Pro, I
published the photo
points to AGOL as a
3D web scene
✓ Shared the scene so
project collaborators
could view online

11. Lessons from Reconnaissance
✓ The bark beetle
outbreak has
affected this area
significantly
✓ Large amount of
blown-down beetle
kill trees presents
a serious
challenge to trail
construction

12. Mapping the Blowdown
✓ Need detailed data that shows the downed trees
✓ Luckily, lidar was collected for Summit county in
2016 by the CWCB & CGS
✓ But, how to use the Lidar to find the blowdown?
✓ First I tried creating the two most common elevation
surfaces, a DEM from the lidar ground returns, and a
DSM from the first returns

13. Mapping the Blowdown

14. Mapping the Blowdown
✓ Neither is too useful for this purpose
✓ DEM shows the ground surface below the downed
trees
✓ DSM shows canopy top above downed trees
✓ Need to look at the space in the middle
✓ Time to start experimenting with the lidar!

15. Mapping the Blowdown
✓ I started experimenting with different combinations of
filters on the lidar
✓ What worked : Filtering out first and second returns,
leaving returns 3-10 in the data, shows the “middle
space” pretty well

16. Mapping the Blowdown

17. Mapping the Blowdown

18. Mapping the Blowdown
✓ It’s not that big of
an area, so I
visually digitized
the heavy blow-
down areas by
hand off of my
hybrid
DEM/DSM.

19. Mapping the Blowdown
✓ This initial map
was used to
draw a rough
proposed
corridor for the
trail.

20. Mapping the Site
✓ The lower loop trail
winds through the
neighborhood
✓ Proximity of trail to
home lots and
wetlands was a
concern
✓ Needed to map
subdivision lot lines

21. Mapping the Site
✓ Surveyors provided the data for the lot lines, but
with an unknown coordinate system
✓ Could not get info on the coordinate system
✓ Solution: Georeference lot lines using corner
points in the GCDB and surrounding parcels
from Summit Co assessor’s data.

22. In the Field
✓ Now it’s time for some field work
✓ Trail planning experts from Contour Logic are using
Trimble GNSS units linked to ArcGIS Collector on
tablets in the field
✓ Problem: There is currently very little to no cell service
on the Summit Sky Ranch property

23. In the Field
✓ Solution: Sync-enabled feature services hosted in
AGOL and deployed in an offline web map in Arc
Collector on mobile devices
✓ A bit of trouble getting raster (tiled) services to
download for offline use in Collector on mobile device
✓ Otherwise, smooth sailing

24. In the Field

25. In the Field

26. Ongoing Work
✓ Contour Logic field
crews have been out
surveying the route of
the lower loop trail this
summer using Arc
Collector

27. Ongoing Work
✓ Construction has begun on parts of the loop trail as
well as the park
✓ Initial field work for the
Maryland Creek trail
has begun

28. Fun Fact!
✓ The car crash scene from National Lampoon’s
Christmas Vacation was filmed on the Maryland Creek
property in 1989

29. Thank You for attending!
Nick Viau – Allpoints GIS | nick@allpointsgis.com