Using GIS Data for Your Byway 
Stephen Clyde 
NSB Website Team


Overview 

-What is GIS?
-What can be done with geographically referenced data?
-Common challenges 
-Tools for working with GIS data 
-What GIS data are available for the byways? 
-Other sources for GIS data 


What is GIS? 
-Geographical Information Systems 
(GIS) are computer-based systems that facilitate the input, storage, manipulation and output of 
geographically referenced data 

Examples: 
-Land cover 
-Cultural areas 
-Byways 
-Project locations 

IMAGES: Land cover for part of Maryland 
Byway Routes
Project Locations
Cultural Areas


Geographical Data 
Three basic elements:

-Points e.g., project locations, points of interest, etc. 
-Lines e.g., roads, borders, small rivers, etc. 
-Shapes e.g., large rivers, lakes, culture areas, etc. 

These basic elements can have “attributes” that describe them in more detail or connect them to additional data 

Elements with different attribute values can look different (color, font, etc.) 


IMAGES: Projects Colored by Type
Projects with Dots Varying According to Funding Amount 


Layers 

One of the powerful features of GIS is the ability to compose multiple layers 

Layers can be added and removed quickly 

Examples: 
-Projects along byways 
-Projects and land cover 
-Byways and culture areas 
-The America’s Byways® map 

IMAGES: Cultural Areas with America’s ®Byways®
Layers in America’s Byways® Map 



So, What Is GIS Good For? 

Five general uses of GIS 
Mapping   				MapQuest 
Route or Directions Computation   	GoogleMaps
Visualization 				Elevation Chart  GoogleEarth 
Analysis 				Byway Sinuosity 
Planning  				Byway Viewshed
Recreation and Entertainment 		Geocaching 


Common Challenges and Problems 

-Working with different projections 
-Inaccuracy and incompleteness 
-Variations in data collection 
-Inaccuracy caused by simplification 
-Mis-labeled, missing, or wrong attributes 
-Inaccuracy caused by change
-Misinterpretation 

1992 vs. 2001 
Land Cover Data 

Road and Land 
Formation 
Simplifications 

Zip Codes and 
Population 


GIS Tools 
-Tools for creating and manipulating GIS Data 
-Tools for storing / retrieving GIS Data 
-Tools for analyzing GIS Data 
-Tools for viewing GIS Data, particularly over the Web



What’s Easy and What’s Hard 

Easy things 
-Adding layers to a map, assuming the data is available 
-Removing a layer from a map 
-Changing the appearance of components of the map based on data attributes
-Comparing or analyzing data across multiple layers 

Hard things 
-Gathering new data 
-Checking the data for accuracy
-Handling differences in the granularity or projection of data across layers 


GIS Data Available Through NSBP 

Downloadable free data 
	GIS file containing your byway route 
	GIS file containing points-of-interest near your byway 
	Adobe Illustrator (AI) or PDF files of our standard map for your byway

Free data, based on approval from FHWA 
	Other byway routes
	Points of interest near other byways 
	AI or PDF files of other byway maps 

Data available for a fee 
	Custom GIS data files 
	Custom maps 


Some Sources for GIS Data 

USGS has good data http://store usgs gov 

Good information about GIS and free sources 
including tiger data on:including tiger data on: 
http://www.census.gov/geo /www/index.html shape files will be available this fall. 

Most state DOT departments have free data for their state. 

ESRI has map drawing and manipulating programs, along with data. 
See http://www.esri.comp

Web search for GIS data or open GIS 

Questions? 

IMAGE: (2 images) Example of Using GIS Data for Analysis: Byway Sinuosity;
Example of Using Data for Planning: Viewshed 
Example of Using Data for Visualization: Elevation Chart 
Differences in Land Cover Categories: Sky Island Scenic Byway 
Inaccuracies Caused By Simplifications