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P.O. Box 7672
Tahoe City, California 96145
(W) 530-583-9128
(H) 530-583-4297
Fax 530-583-1372
donaldhays@thegrid.net

TRAIL SURVEYING, MAPPING & GIS SERVICES
GIS Trail Mapping & Trail Condition Surveying

With over 30 years of trailbuilding behind me, I use my experience and equipment to perform condition surveys for you. I identify objects that have failed, that are needed, or that are a future problem. Services include digital photos of the objects and identification of their locations. This is entered in the trail log as a feature and shows on the map or report. All trail (line) information may be broken down into segmented lengths according to their condition, with "Routine Maintenance" being best condition, to "Install New" being worst condition (see sample report). This could be considered equivalent to a home inspector inspecting a house before sale or for insurance purposes. You want someone that has done it before.

This way, you pay only for the service as needed.  No need for crew training, or mistakes in data collection resulting in lost time and expenses.

Each trail within the trail system is in its own file. Information can be shown or queried as an individual or as a group of trails. I provide both "raw data" and "differentially corrected" data, cleaned of vertices and exported to any of the projections and units listed below.
"Line" or trail information is recorded every five seconds for location accuracy. This way, any deviations in the trail are recorded.
"Points", or something along the trail such as a sign, have minimum of five position stamps each.
"Polygons" have area such as campgrounds, lakes or trailheads and are recorded similar to lines.

Equipment
With state-of-the-art "Trimble Pro XRS" and "TSC1" GPS data loggers, the results are within one to two feet of the actual location.

For extended fieldwork, I use solar panels with doublers (SunWize Portable Energy Systems) with inverters to power battery chargers, laptop computers and satellite telephones.

When I data collect on ATV or motorcycle trails, I have and use low impact "fat tire" motorcycles so I do not damage the trails.

I use ArcView software for delivering GIS ready maps or "projects" to land owner or their representative on CD.  Paper maps and, or reports are delivered for review. Graphic designers may request information in EPS or specific formats for final mapmaking or kiosk-size maps.

Custom Data Dictionaries
If you have your own GPS instrument and all you need is a trail specific data dictionary, I can design a simple to read and use data dictionary for you or your crews to use in the field on your own. I can tailor any type of trail data dictionary you specify. I can build data dictionaries with or without feature codes to assist in database management.  Either by visits on site or verbal specifications requests by GIS specialists, I can prepare a data dictionary right for your specific application.
 
Please note that data dictionaries cannot be downloaded into some small handheld GPS units.
 
Data Dictionaries
Data dictionaries are the backbone of all data collection.  A data dictionary is an electronic form enabling us to capture and record specific attribute information about three types of "objects": line segments, points, and area features.
 
Line Segments are used to describe linear objects such as trails. Line segments (part of a trail) can have many attributes such as:
Trail surface: surfaced or unsurfaced, surface type
Trail width: width in inches, single track? multi-user? bi-directional?
Trail users: extreme bicyclists and motorcycles? pedestrians and wheelchairs? equestrian-pedestrian? etc.
Trail grade: how steep is it?
Bridges and raised trail beds have different attributes and lengths. They are given their own segments with their own unique attributes. Attributes may include, for example:
abutments: wood, concrete or none;
border type: wood, rock or timber

Points are objects such as waterbars, gates, and signs. These objects have no length or width and are "nested" on the line segment. They have different attributes than lines. For example:
log, timber or rock waterbars
metal, wood or wire gates
plywood, plastic or metal signs on what kind of post

Areas can be lakes or meadows, parking lots, individual campsites, or campgrounds. Campsites, for instance, have different attributes from parking lots, campgrounds, lakes, or meadows.

How many obstacles or features are on the trail?
Obstacles or features may be man made points or lines such as gates, drainage structures, barriers, bridges, steps, etc. Features may be obstacles in some cases. Some user types may not be able to climb steps, navigate long steep grades, narrow trails, or get through gates, past waterbars or over roots for instance.

Anyone can build a map...but what condition is your trail in?
Line segments change as conditions change. For example, trail width and erosion may vary, and landslides or washed-out bridges need to be identified and repaired or replaced. Are there rocks or water in the trail? Is the raised trail bed holding up to traffic? Point features may be vandalized or stolen, and fallen trees need to be located. How many signs need replacing? How many and large are the trees? Areas need to be cleaned or repaired. No matter what you want to know, we can put it into a data dictionary. See sample report. Information can then be put on a digital photograph or topo map, highlighting attributes and their unique values, or not.

Any feature may be turned "on" or "off" on the maps. This may be helpful for budgeting. For example if you want to have a repair crew go to only points that need repair, or segments that need to be realigned. From the same information, a public map can be made "hiding" the attribute information showing only the line.

Separate reports can be in spreadsheet or data base file form listing features and attributes in the order they are recorded.
 
Data Dictionaries may be as simple or complex as desired
Data Dictionary Features are:
1. Lines
2. Points
3. Areas

Feature Attributes are:
Date field for update of features
Menu Items include as many sub items as needed
Numeric Items may or may not have decimal places
Text Items may have up to 100 characters
Time field for tracking progress

Line, point and area features may have as many attribute values as needed:
All values may be included in final reports
All Line, Point and Area features can be projected with background maps

Data Dictionaries may include up to two separate code values (valuable for downloading into existing databases).

Generated attributes may have all or any combination of:
Feature types:
  • PDOP values
  • Feature Name
  • Total Positions
  • GPS Second
  • Correction Status
  • Time Recorded
  • Filtered Positions
  • Receiver Type
  • Update Status
  • Data Dictionary
  • Date Recorded
  • Data File Name
  • GPS Week

Line Features may include any or all of the following:
  • 2 Dimensional Line Length
  • Worst Vert. Precision
  • 3 Dimensional Line Length
  • Worst Horiz. Precision
  • Average Vert. Precision
  • Line ID
  • Average Horiz. Precision

Point Features may include any or all of the following:
  • Height above Elipsoid or above Sea Level
  • Point Position
  • Vert. Precision
  • Point ID
  • Horiz. Precision
  • Standard Deviation

Area Features may include any or all of the following:
  • 2 Dimensional Area
  • Average Horiz. Precision
  • 2 Dimensional Perimeter
  • Worst Vert. Precision
  • 3 Dimensional Perimeter
  • Worst Horiz. Precision
  • Average Vert. Precision
  • Area ID

Coordinate System may be any configuration desired. Common projections are, but are not limited to:
  • UTM
  • Lat-Long
  • State Plane

Data may be exported in many different formats. Most common are:
  • ArcInfo
  • ArcView
  • AutoCad
  • Configurable ASCII
  • dBase
  • many others

Position Filters include:
  • Realtime Differential
  • Realtime WAAS
  • RTK; fixed or Floating
Unit Measurement (area, distance, or velocity) can be any unit you want from:
  • Inches to Miles
  • Millimeters to Kilometers
  • Survey feet
  • Chains
  • Links
  • Many others


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