Planning and environmental assessment are transportation priority areas with high payoff potential for remote sensing. Planning is based on knowledge about the current state with some prediction as to how the state will change in the future. For long-range transportation planning by Federal, State, or metropolitan planning organizations, the information requirements may be less stringent as the focus is on characterizing general trends. Predicting the future is more precise if it is based on the historical trend projected through the present. The outcome of this process is to obtain a metric on trends and to steer thinking and planning activities internal to the organization. The accuracy of the prediction depends on the analysis method employed. Generally, however, data used for planning purposes is not required to meet precise accuracy standards.
Because the environmental assessment processes is complex and usually involves many players with different agendas, there is a pervasive perception that the environmental process results in extensive delays and additional costs in completing transportation projects. Part of the problem stems from the fact that the roles and responsibilities of federal, state, and local agencies are often in conflict. 
As a result of widespread concerns about delays, duplication of effort, and additional costs associated with NEPA and other environmental review processes, the US DOT, in response to Section 1309 of TEA-21, implemented a coordinated review process for construction projects that require environmental assessment. The goal of this review process is to establish performance measures and benchmarks to evaluate transportation and environmental decision-making for the purpose of reducing project delays.
Environmental streamlining brings together the timely delivery of transportation projects with the protection and enhancement of the environment. It is generally assumed that greater efficiency in acquiring and analyzing data used in EIS preparation, and better data standards, would reduce EIS preparation time and possibly result in less controversy over the report's findings. Environmental or development planning requires geospatial information about the distribution of landscape features. It is felt by many in the transportation industry that high-quality databases that are maintained with current or frequently updated geospatial information would streamline road development projects. Maps, and to some extent aerial photographs, are the traditional sources of this information. Remote sensing offers tremendous potential for planning purposes because it not only affords a picture of the current state, but unlike aerial photographs, multispectral data can be used to provide information classes, such as land cover and land use.
Remote sensing has numerous advantages over traditional data sets-it is unobtrusive; one can 
collect information simultaneously over a broad range of the electromagnetic spectrum; it is capable of making biophysical measurements; information can be acquired through clouds at long wavelengths; data can be collected in a very short timeframe with aircraft platforms and frequently with satellite platforms; data collection procedures are systematic thereby eliminating sampling bias introduced in some investigations; and analysis methods are relatively robust, objective, and repeatable. This is not to say that remotely sensed data necessarily replaces existing data sets, but in many cases it provides supplemental information that can lead to improved assessments.
Continuity in temporal classification of land cover and its extension to land use can play a significant role in preparation of a comprehensive development plan, implementation of "smart growth" initiatives, and are invaluable in the planning stage of road development projects. Most major metropolitan areas face the growing problems of urban sprawl; residential and commercial development is replacing undeveloped land at an unprecedented rate. Urbanization worldwide continues at a rapid rate and it is estimated by the United Nation's Population Fund (1999) that by the year 2025, 80% of the world's population will live in cities. Sprawl results in a loss of natural vegetation and open spaces and a general decline in the spatial extent and connectivity of wetlands, wildlife habitat, and agricultural lands. While land use changes are a consequence of national growth, regional assessments of historical and contemporary land use change are needed to anticipate the impacts associated with change and contribute to an understanding of productive environmental sustainability.
Land cover and land use changes as a result of sprawl can be substantial, but are difficult to grasp when they occur incrementally. Data from satellites has dramatically illustrated the rates at which these human-induced changes are occurring nationwide. Temporal mapping from satellite data has successfully demonstrated the utility of integrating existing historic maps with remotely sensed data and related geographic information to dynamically map urban land characteristics for large metropolitan areas. These regional databases provide a strong visual portrayal of recognized growth patterns, and dramatically convey how the progress of modern urbanization results in profound changes to the landscape. Temporal analysis of imagery data also allows calibration of transportation policy alternatives and identification of future trends using modeling.
