Conditions and Performance Chapter Listing

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Introduction

Mobility

By most measures the United States is the most mobile nation on earth. Most of us have the opportunity to be selective of the location where we work, where we live (even at some distance from our job), and where we shop, yet there are sectors of the population which have less than the average mobility. Traffic congestion is a problem that faces almost everyone who lives in the larger cities in this nation, and to some degree in smaller cities as well. Do we really know how much congestion exists and what it is costing us? Is there a better way to analyze the need for highway improvements that are intended to reduce congestion and to determine which improvements are best?

Personal Mobility

According to Chapter 1 of this report, certain population groups are not accommodated as well as the average person by our transportation systems, both highways and transit. The major factor affecting the use of our transportation systems is economic. For example, if one cannot afford to buy and operate a car, one's opportunity to travel becomes limited to other modes. Population groups categorized by age, gender, or ethnic origin may also be at a disadvantage. Part of this is because these groups have a lower income than average. But even those within the group who receive an average income may not receive average service. This may be because of reduced personal mobility, as with the elderly, or it may have a geographic component, as may be the case with ethnic groups. Working mothers may need to go by the grocery store and the day care center on the way home from work. People that need to do trip chaining may find the use of a car a necessity and for them the use of transit may not be practicable.

Why are some groups or subgroups at a disadvantage in the transportation system even when they are not economically disadvantaged? Is it geography? Do they live in an area not well served by transportation systems? Does transit provide the service they need? Does it provide a reasonable service between where they live and where they could work, shop, or participate in other activities? Are these questions relevant at the national level, or are these matters best left to the local level?

Congestion

Everyone claims to know what traffic congestion is but a precise quantification is difficult. Measures of the operational performance of our nation's streets and highways can be difficult to obtain or define. Congestion in one city is not necessarily perceived the same as in another. In some cities commuters struggle with an hour of congestion in morning and again in the afternoon. In other cities, congestion occurs for 8 or 10 hours a day.

In some cities transit plays a significant role in travel, and therefore reduces highway congestion compared to what it would be without transit. We can hardly imagine New York City without its subway system. An analysis of the tradeoffs between transit and automobile travel would include the role of transit in reducing highway travel and therefore highway congestion. While this type of analysis may be done at the local level to establish the need for new or expanded transit systems, how can this impact be addressed at the national level?

The Volume/Capacity (V/C) ratio has long been used in this report as a measure of congestion, but it has weaknesses. It only addresses the peak hour, which may be the only congested time or may be only one of many congested hours of the typical day. Also, a V/C ratio of less than 1.0 (say 0.9) may describe a facility approaching capacity (Level of Service E) or a facility that has been reduced below capacity by congestion (LOS F). Delay as a measure of congestion has recently come into some prominence; however, it has been difficult to measure and apply.

Chapter 4 of this report cites two sources of calculated delay. One is delay based directly on HPMS data, and calculated from recently formulated travel speed equations. This delay includes delay at traffic signals and stop signs. The other measure reported by the Texas Transportation Institute is based less directly on HPMS data and uses travel per lane as a surrogate for congestion. Their procedures are based on rather simple assumptions, but do include an estimate of delay caused by roadway incidents, such as accidents. Two other measures that have been proposed are travel speed and reliability. The average traveler, whether commuter or shopper, would like to travel at a speed not slowed by congestion or frequent "red" traffic signals. Industries which depend on transportation need a reliable system that can guarantee a given level of performance, providing for "just in time" deliveries. A trip that takes one hour one day and one and a half hours the next day does not provide that service.

Today, the variety of congestion measures creates uncertainty and confusion about how much congestion exists and whether it is getting worse, better, or is about the same as last year. When a measure of congestion is tied to the agency performance measure or goal, a defensible and reliable measure is needed. We need accepted, easily understood measures for which data can be readily collected.

Life Cycle Cost Analysis

The FHWA encourages the States to use Life Cycle Cost Analysis (LCCA) in their determination of pavement types and designs. This type of analysis can be used to evaluate a total stream of costs and benefits over a significant period of time, say 40 years, to compare alternative highway improvement actions. It can include the cost of delay to the user of pavement actions, maintenance and capital improvements. It can be a useful tool to evaluate alternative pavement investment strategies.

If FHWA is to promote the use of LCCA to the States, should FHWA also use LCCA in its own analyses of current and future highway capital investment requirements? The HERS process currently does look ahead at costs and benefits of potential highway capital investment actions. However, HERS does not compare resurfacing with reconstruction on a fully implemented LCCA basis. It does not consider the cost of delay to the user of improvement actions proposed, now or in the future. It does not compare a 20-year pavement design with a 40-year design. Should these elements be considered at the national level? If so, would the national analysis be making a false assumption about what the States will do in their stewardship of the highway systems? Would such analytical capabilities be useful and informative at the national level?