Douglas S McLeod

Modeling the Roadside Walking Environment: Pedestrian Level of Service

A method is needed to objectively quantify pedestrians’ perception of safety and comfort in the roadside environment. This quantification, or mathematical relationship, would provide a measure of how well roadways accommodate pedestrian travel. Essentially, it would provide a measure of pedestrian level of service (LOS) within a roadway environment. Such a measure of walking conditions would greatly aid in roadway cross-sectional design and would help evaluate and prioritize the needs of existing roadways for sidewalk retrofit construction. Furthermore, the measure can be used to evaluate traffic-calming strategies and streetscape designs for their effectiveness in improving the pedestrian environment. Such a measure would make it possible to merge pedestrian facility programming into the mainstream of transportation planning, design, and construction. To meet the need for such a method, as well as to fulfill a state mandate to establish levels of service standards for all transportation modes, the Florida Department of Transportation sponsored the development of the Pedestrian LOS Model. The model was developed through a stepwise multivariable regression analysis of 1,250 observations from an event that placed 75 people on a roadway walking course in the Pensacola, Florida, metropolitan area. The Pedestrian LOS Model incorporates the statistically significant roadway and traffic variables that describe pedestrians’ perception of safety or comfort in the roadway environment between intersections. It is similar in approach to methods used to assess automobile operators’ level of service established in the Highway Capacity Manual.

Quality-of-Service Perceptions by Rural Freeway Travelers: Exploratory Analysis

In recent years the Transportation Research Boards Highway Capacity and Quality of Service Committee (HCQSC) has debated how performance measures for defining level of service (i.e., service measures) for a facility should be selected. The historical approach has been for the HCQSC to select the measure (or measures) thought most appropriate. However, some committee members have been suggesting that the selection of service measures should be based on research involving the driving public at large and that this research should either directly or indirectly obtain information from drivers and passengers on perceptions of quality and level of service. A preliminary investigation determining the factors that affect traveler-perceived quality of service on rural freeways using in-field surveys of motorists traveling on rural freeways has been conducted. In regard to quality of service, it is becoming more evident that travelers consider multiple factors, and the results from this study support that notion. Specifically, the survey shows that most respondents consider three or more factors important in determining their quality of service on rural freeways. Although density still appears to be a primary factor affecting perceived quality of service, additional factors, such as speed variance and percentage of freeflow speed, seem just as important to travelers. In addition, some nontraffic-performance measures, such as pavement quality and driver etiquette, were found to be important.

Multimodal Level-of-Service Analysis at Planning Level

Methods of determining the level of service (LOS) to scheduled fixed-route bus users, pedestrians, and bicyclists on arterials and through vehicles are presented. The research is based on LOS research for the individual modes and uses a comprehensive arterial approach based on research conducted in Florida. The Florida Department of Transportation (FDOT) developed a multimodal LOS analysis process to measure and provide mobility for diverse roadway users. In 1999 the Florida legislature authorized creation of multimodal transportation districts. It also directed FDOT to develop methods for the measurement of performances of various transportation modes to assist local governments with concurrency requirements for growth management. The Highway Capacity Manual’s (HCM) assessment of arterial LOS does not describe the quality of transportation service provided by the facility as much as it describes the quality of service provided to the through vehicle (automobile) users on the facility. Although this concept does address the primary mode of travel, it does not address the service that the arterial provides to other major potential modes (e.g., transit, walking, bicycling) or allow a multimodal LOS analysis. In the 2000 HCM, LOSs for pedestrians and bicyclists are essentially based on how crowded the respective modal facilities are. However, recent research on quality of service for pedestrians and bicyclists indicates that the most important factors are the lateral separation of the mode and motorized vehicle volume, speed, and type and frequency of transit service. FDOT’s research has applied these models with planning-level assumptions.

Performance Measures for Truck Level of Service: An Exploratory Survey Analysis

The current Highway Capacity Manual (HCM) provides analytical methods to evaluate performance levels of transportation facilities and to estimate level of service (LOS) perceived by the users. The HCM methodologies yield a single LOS value for all users in a traffic stream. However, because of the unique size and operating characteristics of large trucks, truck mode users may perceive LOS on various roadway facilities on the basis of different criteria than those of other mode users. A study was conducted to determine, from an LOS perspective, what roadway, traffic, and control issues should be focused on to better serve the needs of the trucking community. This paper describes the second part of the study, in which a survey of truck drivers and truck company managers was performed to quantitatively measure the relative importance, satisfaction, and improvement priority of truck LOS determinants and to examine which aspects of a truck trip should be analyzed to estimate truck LOS on each roadway type. Speed variance and pavement quality were identified as the service measures for truck LOS on freeways, while percent time being followed, percent time spent following, and travel lane and shoulder width and their pavement quality were identified for truck LOS on two-lane highways. Truck trip quality on urban arterials was found to depend on factors such as ease of turning maneuver, speed variance, traffic density, and pavement quality. Other drivers’ behavior, pavement condition, level of congestion, and frequency and timing of construction activities were common major contributors to truck LOS regardless of roadway type.

MULTIMODAL CORRIDOR LEVEL-OF-SERVICE ANALYSIS

The 2000 release of the Highway Capacity Manual (HCM) provides for the first time a corridor analysis method that guides users in the application of various chapters of the HCM to the analysis of automobiles and transit in a corridor. Together with the recent publication of the Transit Capacity and Quality of Service Manual (TCQSM), the HCM 2000 represents a significant advance in the direction of multimodal level-of-service (LOS) analysis. However, relatively little guidance is given in either the HCM or the TCQSM on the compilation of automobile and transit segment levels of service into a measure of corridor level of service. In addition, bicycles and pedestrians are ignored in the corridor methodology. A methodology was developed and tested in Florida for measuring and reporting the user-perceived quality of service for highway corridors from a multimodal perspective. Automobile and transit LOS analyses are based on the HCM 2000 and TCQSM, respectively. Bicycle and pedestrian levels of service are based on the bicycle and pedestrian LOS models, respectively. Four classes of corridors are recommended, and the methodology was tested on two classes of urban corridors, with and without a freeway. The methodology is applied in three steps: (a) corridor definition, (b) computation of modal level of service, and (c) reporting of results. The methodology was applied to six case studies throughout Florida at generalized and conceptual planning levels. Conclusions about the methodology were drawn from the case studies; the main conclusion is that the methodology provided a reliable overall indicator of corridor level of service by mode.

Freeway Capacity Estimation Method for Planning Applications

The capacity of a freeway segment is a critical factor for the planning, design, and analysis of freeway facilities. The Highway Capacity Manual (HCM) is considered to be one of the authoritative sources on capacity values for a variety of roadway types in the United States, particularly for planning purposes. For basic freeway segments, a single set of capacity values are provided as a function of free-flow speed. Although these values are considered to be reasonably representative values for freeways located throughout the United States, the HCM does not provide any guidance on how its recommended values can be adjusted to reflect significant differences in capacity due to local conditions, nor how to directly measure or estimate capacity values. With the recent development of a statewide freeway traffic data archive in Florida, the Florida Department of Transportation (FDOT) desired to use these data to determine if the freeway capacity values in the HCM were appropriate for Florida freeway level of service analyses for planning and preliminary engineering applications. This study evaluated two previously published methods for estimating freeway capacity, identified their advantages and disadvantages for use in planning applications, and ultimately recommended a method for use by FDOT. One of the chosen methods determines capacity from a mathematical function generated from speed-flow data points and the other chosen method uses the concept of breakdown probability distribution to determine capacity. Neither of these methods proved desirable for planning applications due to computational burden; thus, an alternate, simplified approach was developed that used a simple averaging method of highest flow rates to determine capacity.

Revised Version of the Automobile Level-of-Service Methodology for Urban Streets in the Highway Capacity Manual 2010

The Highway Capacity Manual 2010 (HCM 2010) contains a significantly revised automobile analysis and level-of-service (LOS) methodology for arterials. This study compared the arterial LOS results of the HCM 2000 and HCM 2010 methodologies for an experimental set of arterial segments and analyzed the effects of the revised methodology. In addition, existing Florida field data sets were also analyzed with arterial segments obtained from Gainesville, Tallahassee, and Tampa, all in Florida, as well as data received from the Florida Department of Transportation Districts 2 and 3. The HCM 2010 results showed that for shorter, lower-speed arterial segments [such as in central business districts (CBDs)] it was not possible to obtain LOS Ratings A or B. Therefore, many CBD arterials that had good LOS values under the HCM 2000 methodology would now have moderate to poor LOS values. Consequently, the research team tested several revisions of the HCM 2010 methodology to find an approach that would not be as punitive to arterials with shorter segment lengths and that would provide a good balance of LOS values across a range of segment lengths, posted speeds, and traffic demands. Suggested revisions to the HCM 2010 methodology that allowed this objective to be achieved consisted of the following: the use of two classes instead of one (on the basis of the posted speed); the use of the average travel speed as the service measure instead of the ratio of the average travel speed to the base free-flow speed; and the setting of the free-flow speed to equal the posted speed plus 5 mph, instead of using the free-flow speed computations in the HCM 2010 methodology.

Adaptation of Highway Capacity Manual 2000 for Planning-Level Analysis of Two-Lane and Multilane Highways in Florida

A planning-level adaptation was developed of the Highway Capacity Manual (HCM) 2000 procedure for estimating the level of service (LOS) on two-lane and multilane highways in Florida. The problems associated with planning-level adaptations in general and with uninterruptedflow highways in particular were identified. Although much of the adaptation was achieved though the use of default values for data items, some departures from the HCM procedures were required. The most significant deviation was the creation of a third class of two-lane highway to supplement the two classes currently defined in the HCM. A case was made for the existence of this class and its inclusion in a future edition of the HCM. The Florida Department of Transportation’s planning-level methodology, termed HIGHPLAN, is well suited to its intended application, which is planning-level analysis of two-lane and multilane highways in Florida. It maintains fidelity to the HCM procedures to the extent that Florida conditions will allow and Florida users will accept. As long as they are understood, the departures from the HCM should not pose significant problems for users outside of Florida. The planning-level methodology has also been implemented in a software program that produces LOS estimates and service volume tables covering sitespecific conditions.

FREEWAY PLANNING METHODOLOGY

A major new chapter of the Highway Capacity Manual (HCM) 2000 is on freeway facilities. It is a detailed operational methodology that combines analyses of basic freeway segments, weaving areas, off-ramp areas, and on-ramp areas. However, the new chapter does not contain guidance or examples for planning or preliminary engineering applications. To meet its numerous needs, Florida Department of Transportation engineers wanted to develop a freeway facility application that extends the HCM for generalized planning and preliminary engineering purposes but is not inconsistent with HCM 2000. Such a methodology was developed, documented, made into an executable software program called FREEPLAN, and is now being implemented throughout the state. The methodology is firmly based on HCM detailed analysis procedures but has assumptions and defaults that allow planners and engineers to use it effectively. At a generalized planning level, the basic construct was to provide tables of design volumes, v, and annual average daily traffic that could be achieved for various levels of service and freeway configurations for the default parameter values. At a preliminary engineering level, specific freeway facility inputs are used to determine v/c ratio, average travel speed, average density, and level-of-service grades. The initial results of applying the Florida freeway planning methodology to actual Florida data were outstanding in both urbanized and rural areas.

Special Features of Florida's Mobility Management Process

The purpose of the Florida Mobility Management Process (MMP) is to improve the mobility of residents and tourists. Although all states must develop congestion management systems (CMS), special features of the Florida CMS, which others may wish to consider, are presented. Floridas special MMP features include: development framework, applicability of MMP and CMS to all urbanized areas, MMP and CMS relationship with the transportation planning process, multimodal alternatives analyses of major investments, institutional arrangements, implementation techniques, performance measures, and MPO prototypes.