GIS for Transportation: Principles, Data and Applications

1.1 Introduction to GIS-T


Among the many areas and disciplines to which GIS has been applied, transportation has been particularly fertile ground, and the development of specialized GIS applications has been an area which has seen a lot of activity. This important interdisciplinary field is commonly referred to as GIS-T. The significance of this field is evidenced by the fact that there are two conferences devoted to it, one annual and one biennial. Each year the American Association of State Highway and Transportation Officials (AASHTO) sponsors the annual GIS for Transportation Symposium. The symposium draws over 400 registrants from federal, state, and local government and the private sector. The Urban and Regional Information Systems Association (URISA) sponsors a conference called GIS in Transit which is held every other year. The 10th GIS in Transit conference was held last year.

A key reason that GIS-T is so important is that transportation is a huge industry upon which many other industries depend. In 2015, the federal government spent 85 billion dollars on transportation-related initiatives. That represented 2.22% of our total federal budget for 2015. The National Priority Project (NPP) website presents some interesting charts which put federal transportation spending in perspective.

Additional Learning

In their own words, the NPP “is a national non-profit, non-partisan research organization dedicated to making complex federal budget information transparent and accessible so people can prioritize and influence how their tax dollars are spent.” Their website also offers a number of very educational videos if you’d like to understand our national budget, deficit, and debt.

In addition to federal dollars, there are many billions of state and local dollars spent on transportation. If you want to see how states are using transportation dollars, the Track State Dollars website gives you access to data for each state.

In the U.S., federal agencies have helped to promote GIS use for transportation analysis purposes through geospatially-enabled initiatives such as the U.S. Census Bureau’s TIGER program and the Federal Highway Administration’s Highway Performance Monitoring System (HPMS). Software vendors have continually updated and improved their GIS products to include additional GIS-T functionality and tools. Today, GIS-T is an integral part of transportation operations around the world.

The natural synergy between GIS and transportation is at least in part due to the fact that transportation is inherently spatial, and while it’s true that GIS plays an important role in transportation, one can also argue that transportation plays an important role in GIS. Transportation features are frequently included on maps for context and orientation even when the fundamental purpose of the map has little or nothing to do with transportation.

Assignment 1-1 (20 points)

Read the article "GIS-T in the 21st Century"  by Harvey Miller and Shih-Lung Shaw (the article can be accessed in Assignment 1-1 in Canvas). In this article, Miller and Shaw identify 20th-century GIS-T topics which are still relevant in GIS-T today in addition to topics which have become important in the 21st century as the field has evolved and the needs of the transportation industry have changed.

Submit an M.S. Word document (no more than 500 words) to Assignment 1-1 in Canvas which addresses the following items:

  1. According to the authors, what are some of the enduring principles of GIS-T that remain relevant in the 21st century? (5 points)
  2. What are some of the underlying forces which are transforming transportation and GIS-T in the 21st century? (5 points)
  3. The authors cite a major shift in GIS-T from aggregate and static analysis to one focused on individual activities and spatiotemporal analysis. What does this mean, and what are the forces leading to this shift? (5 points)
  4. Define the concept of a location based service and provide a few examples. (5 points)

Overview of the Transportation Industry

Broadly speaking, the field of transportation is concerned with the transport of people and goods. To appreciate the value that GIS brings to transportation it is necessary to develop an understanding of the various forms of transportation that exist and also the types of activities and problems which those in the field need to address.

Transportation Modes

The different ways that people and freight can be transported are referred to as transportation modes. There are many different modes of transportation, and they can be differentiated and categorized in a number of ways. At a high level, we can divide transportation into the categories of air, land, sea, and space. We could further divide the land-based transportation into road, rail, pedestrian, bike, and pipeline, although one might rightfully argue that pipelines can run under the sea. Transportation modes are not always mutually exclusive and the specific modes we talk about often depend on the situation at hand. There have been many GIS applications which have been designed for a specific mode or for a group of closely related modes.

Assignment 1-2 (15 points)

In Chapter 3 of Jean-Paul Rodrigue’s book “The Geography of Transport Systems”, Dr. Rodrigue discusses transportation modes. Read the following sections of Chapter 3: 

Submit an M.S. Word document (no more than 500 words) to Assignment 1-2 in Canvas which addresses the following items:

  1. Describe the concepts of modal competition and modal shift. Come up with an example of modal shift which was not discussed in the chapter. (9 points)
  2. Define containerization and discuss the impact it has had on the transportation of freight and international trade. (6 points)

Transportation Processes and Activities

Just as we can categorize transportation according to the many modes of transportation which exist, we can think about transportation in terms of the many processes and activities which are performed in order to manage transportation infrastructure, vehicles, and operations. Some of these processes cut across modes and others are specific to a single mode or a few modes. These processes and activities include:

  • infrastructure monitoring and maintenance;
  • transportation planning and transit planning;
  • property acquisition and management;
  • vehicle tracking and logistics;
  • highway safety analysis and improvement;
  • traffic monitoring, modeling, and mitigation;
  • screening projects for environmental impacts;
  • dissemination of travel information to the public;
  • reporting data to government agencies to secure funding;
  • mobile data collection;
  • routing and permitting of oversize overweight vehicles.

GIS-T plays an important role in enhancing the manner in which transportation organizations accomplish these processes and activities and in some cases allow organizations to perform functions which would simply not be possible without spatial technologies. GIS-T applications support evaluation of different scenarios, provide objective data for decision-making purposes, and promote the visualization of conditions.

GIS-T Techniques and Tools

GIS-T utilizes many mainstream geospatial tools and methods but it also employs a number of techniques which were borne out of the specialized needs of the transportation industry. These include:

  • Conflation
    Conflation is a technique used to bring together adjacent or overlapping datasets which were collected at different times and have different levels of accuracy and precision. While the process of conflation in GIS is frequently applied to transportation networks, conflation can also be used to combine other types of features.
  • Network Analysis
    A roadway network is comprised of roads and intersections. In network terminology, the intersections are referred to as nodes, and the streets which connect the nodes are called edges. GIS-T commonly employs network analysis techniques to roadway networks to solve common transportation-related problems such as finding the best route between two points or determining the service area around a specific location (i.e., the area within which someone could reach the location of interest in a defined period of time).
  • Linear Referencing Systems
    Linear referencing systems (LRS) are used to spatially reference the location of assets (e.g., bridges), occurrences (e.g., crashes), and roadway characteristics and administrative data (e.g., speed limits) by specifying the distance along a linear feature in a roadway network. Collectively, these attributes of a roadway are referred to as events. In this course we'll only consider the application of an LRS to roadway networks, they can be used in any linear network including pipelines and hydrologic networks.
  • Dynamic Segmentation
    Dynamic segmentation is closely linked to LRS. In dynamic segmentation, we take the roadway events which are linearly referenced along roadways and transform them on the fly into spatial features. Taken together, LRS and dynamic segmentation allow us to effectively manage and utilize the myriad of attribute information associated with roadway networks. We will explore these techniques in detail in Lesson 6.

We will learn more about these techniques in upcoming lessons.