Lester A Hoel

The “smart growth” debate: best practices for urban transportation planning

Abstract A fundamental public policy decision implicitly addressed by agencies responsible for urban transportation planning is the right of the individual versus the goal of the community. This question arises in considering the role that state and local officials should play within the context of transportation and land development, specifically the “smart growth” movement. Although there is no universally accepted definition of “smart growth”, discrete actions being implemented or advocated under that rubric reveal that smart growth is viewed as a range of regulatory, financial, and educational practices that may help to coordinate transportation and land use through integrated planning. Practices helpful in this coordination include communications, consensus-building, and legislative efforts that improve dialog, reduce polarization, and enable coordination of transportation and land use decisions. None of these practices require use of the “smart growth” label: instead, they expose tangible initiatives that can be publicly debated. Only when referring to specific initiatives (rather than the general slogan “smart growth”) is it fair to ask a community or an organization to take a position on the issue of individual autonomy versus communal desires. This paper discusses critical policy issues facing agencies responsible for land use planning, reviews organizational approaches to resolving smart growth issues, and suggests practices to enhance community participation by delineating tangible components of “smart growth”.

EVALUATING IMPROVEMENTS IN LANDSIDE ACCESS FOR AIRPORTS

Access to airports has become increasingly difficult, but the extent of the problem is not known. No method exists to consistently define the performance of landside access that is provided to air passengers. A national survey of U.S. airport authorities was conducted to determine the characteristics of airport access services provided. The results of the survey indicate that landside access to airports is a major concern at airports of all sizes, but there is no significant difference in reported access problems at large, medium, and small airports. An access evaluation methodology was developed to assess landside access service between approaches to the airport and the terminal entrance and is based on performance measures relating to cost, time, reliability, convenience, and quality. It is intended to aid in the assessment of landside access performance and to promote more effective use of limited resources by determining the most needed and beneficial access improvements. This evaluation methodology was demonstrated by investigating landside access facilities at the Richmond International Airport. The methodology is flexible and may accommodate airports with a wide range of assessment needs and resources. Furthermore, the evaluation process corresponds to existing airport planning, requires no special training to complete, and may be undertaken in cooperation with master plan efforts. It is recommended that the evaluation methodology be incorporated into access fund appropriation processes as a consistent means of evaluating performance, identifying access needs, and evaluating potential access improvements.

Exclusive Lanes for Trucks and Cars on Interstate Highways

Increases in heavy truck traffic on the nation’s highways in recent years have raised concerns about safety and capacity, particularly on the Interstate system. In response, a number of strategies for dealing with the effect of truck traffic on safety and capacity have been developed. One promising strategy is to provide separate lanes for trucks and cars on freeways or Interstates. However, since separate lane strategies have not been widely used, little is known about their economic and operational effects. An FHWA computer model, referred to as EVFS, was evaluated. The model determines the economic feasibility of separating trucks and other vehicles on freeway segments. Practices and experiences with exclusive facilities nationwide were examined. EVFS can analyze many alternatives for a variety of conditions. It is inexpensive and easy to use. However, EVFS does not differentiate between the lanes to which exclusions are applied (inside, middle, outside), and physical barriers are not treated explicitly. To demonstrate the application of the program, 10 lane separation strategies were evaluated for a 50.7-km (31.5-mi) segment of I-81 in Virginia. The results of the I-81 analysis indicate that user savings can be achieved if one or more lanes are designated for the exclusive use of trucks or cars.

Using Simulation to Predict Safety and Operational Impacts of Increasing Traffic Signal Density

The use of simulation models to predict the safety and operational impacts of increased traffic signal density in suburban corridors is described. Using 10 years of data from two major arterials in Virginia, actual crash rates were compared with operational performance measures simulated by the Synchro/SimTraffic model. As expected, crash rates were positively correlated with stops and delay per main-line vehicle and negatively correlated with main-line speed. Three findings were significant. First, the correlation between crash rates and performance measures (main-line delay, speed, stops) was relatively strong despite the inherent variability in crash rates: R2 values ranged from .54 to .89. Second, three distinct regimes relate stops per vehicle to signal density: the installation of the first few signals causes a drastic increase in stops, the addition of the next set of signals causes a moderate increase in stops, and the addition of a third set of signals does not significantly affect the number of stops per vehicle. Third, multiple-regime models also relate total delay per vehicle to signal density. Two practical applications are suggested, one for safety and one for operations. To the extent that these measures correlate with crashes, simulation modeling may be used to estimate safety impacts of increased signals, which is appealing because simulation packages are becoming easier to apply. This safety-oriented endeavor was the primary motivation behind this research. A secondary, operational benefit, however, is that three regime models can suggest when, in the timeline of corridor development, the addition of a traffic signal is likely to degrade corridor performance significantly, thereby allowing decision makers to expend political capital when it is most beneficial.

MOBILITY EVALUATION FOR URBAN PUBLIC TRANSPORTATION

Summary This paper has reported on a study of relative opportunity—not absolute opportunity. Minimum absolute standards for mobility or accessibility are difficult to justify. Some additional study into the development and application of absolute mobility standards may be warranted. The application of the mobility evaluation model has primarily focused upon a corridor line‐haul system. Conclusions suggest that such a system will not markedly improve existing transit mobility levels in either the peak hour or the off‐peak. The experimental work has verified this conclusion, and more importantly, it has detailed quantitatively the exact levels and spatial distribution of mobility improvements. However, this study does not include a comprehensive analysis of all methods of mobility enhancement, nor does it undertake a comparison of alternative means of mobility improvement. Certainly other methods to improve access to opportunities should be explored before policy considerations are finalized. These methods ...

Transferability of Models That Estimate Crashes as a Function of Access Management

Access management can improve safety or operations but may reduce accessibility for adjacent residences or businesses, causing conflict between the needs of local and through traffic and resulting in access management decisions being challenged by the public. Accordingly, transportation administrators require assurance regarding the accuracy of projected safety impacts of access management decisions. Several existing mathematical models quantify these impacts for selected access management techniques. Since new models require substantial resources to construct, it is prudent to investigate the extent to which existing models can be applied in other locations. A study of mathematical models that predict the number of crashes that will result as a function of signal spacing, median treatments, unsignalized driveways, and other key variables is reported. The study compared five models using a 10-year set of geometric, operational, and crash data for three case study corridors. The crash-prediction ability of these models was assessed using traffic flow data other than the data set used to construct the models. Because some of the models were not developed for application elsewhere or were intended to be used only with a site-specific adjustment, the error percentages indicate the extent to which the models are transferable, but they do not constitute a critique of the previous research. With no site-specific adjustment, the accuracy of the models ranges from an average error of 34 to a few hundred percent. With simple site-specific adjustments, errors are in the range of 27 to 29 percent. Substantially less effort is required for these site-specific adjustments than would be required to create a new mathematical model. Recommendations were developed for using these models in practice, understanding their limitations, and interpreting their sensitivity to key inputs, data needs, and computational requirements.

Evaluating Unplanned Stand-Alone Transportation Projects: Linking Incremental and Comprehensive Planning

Transportation agencies may review proposed projects that were not examined as part of the long range planning process. Typically, these projects require an immediate response and lack detailed data. This paper describes a methodology to assess such unplanned or “stand-alone” transportation projects and applies it to two case studies: a large development involving several major new highway sections and a pedestrian crossing of a four-lane arterial bisecting residential and commercial areas. The methodology specifies the trade-offs and uncertainties of the proposed stand-alone projects. For example, adding phasing to an existing signal resulted in a lower capital cost, and a lower feasibility of pedestrian use, than constructing an overpass. Yet, neither alternative assures crash risk is minimized because the extent of pedestrian compliance with traffic laws is not known. The outcome is thus a timely clarification of each alternative’s advantages which can be compared to existing policies. Limitations are ...

TRANSPORTATION EDUCATION IN THE UNITED STATES

Abstract This paper describes the role of transportation education in the United States and the likely direction of transportation education in the future. The evolution of transportation education from a design and operations orientation to one focused on planning, management and policy, is described. This paper discusses various levels of transportation education and their purposes, beginning with university studies for the Bachelor, Masters and Ph.D. degrees, as well as various forms of post‐college training for professionals. The historical basis for transportation education in the U.S. is described and its early beginnings, its functions and current educational programmes are outlined. Also discussed are the institutional framework within which education is delivered in the U.S. and the manner in which courses and programmes of studies are developed, implemented and changed. The emphasis is on educational programmes dealing primarily with public‐sector applications for modes such as highway, rail, ai...

Accuracy of Zonal Socioeconomic Forecasts for Travel Demand Modeling: Retrospective Case Study

Modeling for urban travel demand begins with 20-year forecasts of population, households, vehicle ownership, and employment for a regions individual transportation analysis zones. Yet even though these models rely on socioeconomic forecasts, the long-term accuracy of such models has not received attention, especially for smaller regions with limited planning staff. This paper reports on a case study of the socioeconomic predictions made in 1980 for a horizon year of 2000, by comparing predicted and actual results in Lynchburg, Virginia. The region percentage error reflects the difference between forecast and observed values for the entire region. Although regional forecasts for the number of vehicles and employment showed errors of less than 10%, those forecasts for population and households showed errors of 48% and 14%, respectively. The failure of planned development in two of the regions 68 zones accounted for much of this error, such that removal of these two zones lowered population and household region percentage errors to 10% and 1%, respectively. The zone percentage error is the average of all individual zone percentage errors. Even after removal of the two aforementioned zones, population, households, vehicles, and employment had strikingly large zone percent errors of 39%, 48%, 45%, and 136%, respectively. These results make a compelling case for executing the regional travel demand model twice: once with the given socioeconomic forecasts and once with forecasts modified on the basis of expected errors. For regions that have not conducted an assessment such as that presented here, the expected errors from this paper may be used.

Measuring Pre-Flight Travel Time in the Air Journey

The time taken to get to the airport and the time spent in the airport terminal are two primary phases of an air passenger’s journey. About 1300 departing air passengers were surveyed and individual passenger processing time at the check-in queues were collected at 5 different airports. Data shows that air passengers’ pre-flight time, which is comprised of the ground travel time, processing time, and non-airport activity time, is about the same as their flight time. Passengers arrive at the terminal at suggested hours prior to departure. At the terminal, the spent time at the check-in counters as well as the security queues is not very high. It is the non-airport activity time that is a major portion of the pre-flight time. Data also suggest an inherent and high variability in the various elements of the passengers’ pre-flight time.