Research Components

The Access to Destinations Study includes three major research components, each focused on a different aspect of the complex relationship between the transportation system, land use trends, and travel behavior. Each research component is implemented through research projects.

These components correspond to the overall research goals of the Study, which include:

1. To improve our understanding of travel on freeways, arterials, and other roadways and of travel by non-auto modes, including transit, bicycling, and walking;
2. To develop measures of accessibility using travel and land use data, resulting in a series of maps and tables that present accessibility measures by mode for each destination activity. This will be done for various locations in the Twin Cities region, showing how accessibility has changed from 1995 to 2005;
3. To apply new tools and new knowledge, in order to assess how our existing transportation and land use system can meet alternative policy goals, and evaluate policy options for the future.

I. Understanding Travel Dimensions and Reliability

This research focuses on improving our understanding of travel within urban transportation systems. Large-scale measures are informative but are of  limited use in helping us understand what is happening in specific locations and across a spectrum of different transportation modes. Key questions include whether or not congestion is predictable, and what might be done to make travel time more consistent and reliable. Research in this area will collect additional data to use with existing data sources and models, including Travel Behavior Inventory (TBI) data and census data (the CTPP package), to address the following areas of interest:

1. Freeway travel characteristics. Freeway travel is an important indicator of overall system performance. More detail is needed on travel times and speeds to show how congestion varies by location, time, and condition, especially in determining how predictable travel times are for travelers.
2. Non-freeway travel characteristics. As freeways become more congested, traffic often diverts onto local roads. Although the use of arterials and other non-freeway routes profoundly impacts travel times, data on these effects is limited in scope. Enhanced models are needed to improve estimation of congestion and travel times for local road systems and determine how they are changing in response to increasing freeway congestion.
3. Transit and non-motorized travel characteristics. While data exist on travel times for the mainline bus system, a better understanding of travel by non-auto modes is needed. In order to determine the potential for transit, bicycling, and walking to respond to travel demand, travel data for these modes must be analyzed across a variety of corridor routes, and correlated with local and regional patterns of land use.

>> Research projects for Component I

II. Measuring Accessibility

This research uses detailed data on land use, travel behavior, and population demographics, in combination with the research findings from Component I of the study, to develop methods for describing how our accessibility is changing. Using only congestion measures and travel time data is an incomplete approach to evaluating our urban transportation system, because travel is generally a “derived” demand: people travel in order to reach destinations for work, shopping, education, recreation, and other activities. Accessibility to these destinations is affected by the location decisions made by homeowners, employers, retailers, etc., as well as by travel time. Areas of interest in this research include:

1. Accessibility measures. In order to formulate specific measures that can be tracked over time, it is necessary to create a consistent definition of accessibility and evaluate all available data. Measures of accessibility can then be developed for automobile, transit, bicycle, and pedestrian modes.
2. Land use activities. Destination information needs to be developed from land use data by activity type (e.g., employment, housing, retail, education, and recreation).
3. Accessibility by mode to destinations. Using information from the above efforts, combined with analyses of TBI and CTPP data, a series of maps and tables that show accessibility measures by mode for each destination activity for various geographic locations in the region will be developed. A key goal will be to compare accessibility using 1995 data to accessibility using 2005 data. This will involve looking at how origins and destinations have changed since 1995 and evaluating the degree to which such changes are related to changes in congestion and access.

>> Research projects for Component II

III. Exploring Implications of Alternative Transportation and Land Use Systems

The work undertaken in Components I and II will contribute to the development of an alternative approach to evaluating our transportation system. Current evaluation approaches that use only mobility and reliability measures of congestion can lead to at least two major problems from a policy perspective. First, they may lead to significant effort and resources being directed at reducing congestion, which is only one of many ways to improve access to destinations. Second, since measures of congestion are inherently automobile-centric, solutions involving other modes may not receive the attention they deserve. The accessibility measures developed above will be used to evaluate various transportation and land use policies for the future. Research in this final component will address:

1. Evaluating the current situation. Analyzing the changes in travel time and accessibility from 1995 to 2005 provide a better understanding of historic trends and possible future policy actions. This evaluation allows us to determine which parts of the region have good access to destination activities, which have poor access, and what the implications might be for alternative transportation investments and land use developments. It also reveals which parts of the region that have experienced the largest changes in accessibility—both positive and negative—since 1995. Because there is considerable regional variation, this evaluation requires a detailed geographic analysis.
2. Planning for future transportation/land use systems. The findings from the above efforts will lead to conclusions about accessibility measures and methodologies. Using accessibility as the key measure, the research results will provide methods to evaluate alternative investments in various modes and the implications of alternative land use policies for various geographic areas. Researchers will work closely with Mn/DOT and Metropolitan Council staff to determine the implications of these policy options on the more specific strategies of future transportation plans for the region.

>> Research projects for Component III