Roadway data are fundamental to transportation and GIS-T. Many GIS functions and analyses rely on it including geocoding and network analysis, both of which we’ll take a close look at in the next few lessons. Roadway data also play an important role in mapping and visualization for many GIS applications.
There are a number of commercial and public sources of street data and services which are available. Some are public and freely available and others are commercial. In this lesson, we’ll take a look at some of the most widely used sources of street data.
TIGER data is a data source produced and published by the U.S. Census Bureau. This data includes street data which can be used to perform geocoding or to produce a street network. TIGER data was used as a “seed” for many of the other roadway data sources, both public and commercial. We will take a closer look at TIGER data later in this section.
OSM is a rapidly growing Volunteered Geographic Information (VGI) project which got its start in 2004 and is sponsored by the OpenStreetMap Foundation. For U.S. roads, OSM initially used TIGER Line files but many updates have since been made based on input from its volunteer community which is now over a million strong. In some parts of the world, OSM data are as good, or nearly as good, as its commercial counterparts.
State-level transportation agencies have long maintained road centerline networks as well as additional networks for other modes. They have been improved greatly in accuracy and precision, and agencies are increasingly adding local and private roads and associated data. Much of this latter impetus is due to increased federal requirements for data collection and reporting. In most cases, these networks are the most complete and accurate product for network features and associated attributes for any given state.
Transportation for the Nation (TFTN)
TFTN is an evolving governmental initiative from the National States Geographic Information Council (NSGIC) and USDOT that originated in 2008. TFTN will initially be a road centerline dataset that may replace overlapping federal efforts and products. A set of centerline datasets has been created as part of state DOT submittal requirements for FHWA’s Highway Performance Monitoring System (HPMS). The next step is to try and join these across state lines.
TomTom / Tele Atlas
Tele Atlas was founded in 1984 and was acquired by TomTom in 2008. Tele Atlas data was primarily collected from its own mapping vans. The company’s road products are decreasing in importance and usage.
Nokia / NAVTEQ / HERE
Founded in 1985 and acquired by Nokia in 1991, NAVTEQ (now renamed HERE) operates independently and partners with third-party agencies and companies to provide its networks and services for portable GPS devices made by Garmin and others, and Web-based applications including Yahoo! Maps, Bing Maps, Nokia Maps, and MapQuest.
ESRI StreetMap and StreetMap Premium
ESRI does not produce road data directly but instead acquires it from HERE, TomTom and others and repackages it. ESRI StreetMap covers North America and is part of Data and Maps which is included with ArcGIS. StreetMap premium has more current data than StreetMap and also has coverage for Europe.
Google has become a major provider of mapping services. Google doesn’t make its street data available directly, but instead uses it to provide services. These services are provided through products such as Google Maps, Google Earth, and various APIs. In 2008, Google released a tool called Google Map Maker to encourage individuals to submit or correct feature information. This is similar in concept to the manner in which OSM derives much of its data. Google recently announced that Map Maker will be retired in March 2017 and the functionality will be added to Google Maps.
Assignment 2-1 (20 points)
Complete the following tasks:
- Watch the following YouTube video on Google’s Ground Truth Project. Please allow 40 minutes to view the entire video.
- Explore and compare the editing tools which Google and OSM make available for volunteer contributors. Google provides their Google Map Maker tool. To use this tool, you will need to create a Google account if you don’t already have one. Similarly, OSM provides a tool called OpenStreetMap Editor. To access this tool, browse to the OSM site and sign up for an account (upper right corner of the page). Once you have an account, you can access the OpenStreetMap Editor by clicking the “Start Mapping” button.
- Take a look at this map comparison tool made available by Geofabrik, an organization who promotes OSM and provides a portal for downloading OSM data extracts. For an area you are familiar with, compare the OSM map, the Google map, and the HERE map.
Submit a write-up in M.S. Word format to Assignment 2-1 in Canvas which addresses the following 4 items:
- What do you find most interesting about Google processes for collecting and correcting the data it displays on its maps and uses to support the other services it provides? (4 points)
- If you were to contribute some of your time to improving Google maps or OSM, which would you choose and why? (4 points)
- Compare and contrast the OSM map, the Google map, and the HERE map in terms of accuracy, aesthetics, and/or performance. (4 points)
Exploring TIGER Data
We will be using TIGER data in the next lesson. Consequently, we will spend some time in this lesson becoming acquainted with the manner in which the Census Bureau makes this data available.
The TIGER database was first created in preparation for the 1990 decennial census. In creating TIGER, not only did the Census Bureau produce the first nationwide map of roadways, it also incorporated topographical context which defined the relationship between road features as indicated in its name: Topologically Integrated Geographic Encoding and Referencing database.
In addition to the TIGER spatial database, the Census Bureau also created a Master Address File (MAF) which is a database of all known living quarters in the U.S. The MAF contains about 300,000 addresses which are identified as location addresses, mailing addresses or both. In addition, the MAF contains a record for each living unit which can correspond to a separate structure or a residence within a shared structure. There are about 200,000 living units in the MAF some of which have multiple associated addresses. Following the 2000 decennial census, the Census Bureau decided to merge the two databases into a single database known as the MAF/TIGER Database (MTdb).
The Census Bureau is planning a 3 part informational series on TIGER to commemorate its 25th anniversary. Part 1 will examine the history of TIGER, Part 2 will address efforts to improve its accuracy, and Part 3 will address the tools which provide access to the data. To date, only Part 1 of the series has been made available. Spend a few minutes looking though the document to learn a little about TIGER’s history.
The TIGER data is available in a number of formats including Shapefiles, geodatabases, and KML files. The Census Bureau also provides a tool called TIGERweb which allow online viewing and the ability to incorporate TIGER data directly in GIS applications via web services including an OGC standard Web Mapping Service (WMS). For the exercises in this and the upcoming lesson, we will be working with the TIGER/Line shapefiles.
The Tiger/Line shapefiles are available for multiple years. Each year, the Census Bureau provides an updated set of Tiger/Line shapefiles in addition to associated technical documentation. The technical documentation for the 2016 Tiger/Line shapefiles can be found here. It is over 120 pages long and serves as an excellent reference for the Tiger/Line Shapefiles. Skim through the document to familiarize yourself with its structure and the type of information it contains.
Assignment 2-2 (15 points)
Compare and contrast 3 different TIGER/Line data offerings for the same county.
- Select a county with which you are reasonably familiar. If you do not live in the U.S., select any county you wish.
- Download 2016 TIGER data in shapefile format for “All Lines”, “All Roads” and “Address Range-Feature Shapefile” for the county you selected in Step 1.
- Create a new map document in ArcGIS and load the three shapefiles downloaded in Step 2.
Submit a write-up in M.S. Word format to Assignment 2-2 in Canvas which addresses the following 5 items:
- Provide a separate map screenshot from ArcGIS for each of the three datasets. (3 points)
- List some of the differences between these shapefiles. Based on the resulting maps and the dataset descriptions in the Census Bureau’s technical documentation, compare and contrast the 3 datasets. (3 points)
- In the “All Lines” shapefile, identify the attribute which is used to uniquely identify each edge. (Hint: See the technical documentation for the 2016 TIGER/Line Shapefiles.) Is this field present in all three datasets, and is it a unique identifier for each record? (3 points)
- Identify the dataset you think would be best to use for geocoding and explain why. (3 points)
- Identify the dataset you think would be best to use as a starting point for routing or other network analysis and explain why. (3 points)