The transportation profession lacks a consolidated and generally accepted set of transit-capacity and quality-of-service definitions, principles, practices, and procedures for planning, designing, and operating vehicles and facilities. This is in contrast to the Highway Capacity Manual that defines quality of service and presents fundamental information and computational techniques related to quality of service and capacity of highway facilities. In the absence of a comparable, authoritative document, the case for transit service in a multimodal decision environment is weakened. Therefore, there is a need for a Transit Capacity and Quality of Service Manual.

Transit capacity is arguably more complex than highway capacity: it deals with the movement of both people and vehicles; depends on the size of the transit vehicles and how often they operate; and reflects the interaction between passenger traffic concentrations and vehicle flow. It also depends on the operating policy of the transit agency, which normally specifies service frequencies and allowable passenger loadings. Accordingly, the traditional concepts applied to highway capacity must be adapted and broadened. For this project, "capacity" is defined as "person capacity" as stated in the 1985 edition of the Highway Capacity Manual: "Person capacity is defined as the maximum number of people that can be carried past a given location during a given time period under specified operating conditions..."

"Quality of service" reflects the transit-user perspective and should be measured by a quantitative measurement or prediction of how a transit route, facility, or system is operating under specified demand, supply, and control conditions. The concept of quality of service for transit includes some of the same factors that affect capacity, such as vehicle size, load factor, service frequency and travel time. Travel time is influenced by factors such as stop frequency, dwell times, road and rail traffic interference, and right-of-way design. In addition to the factors that affect both quality of service and capacity, quality of service also includes such items as accessibility, comfort, area coverage, and reliability.

Considerable work has already been done on transit capacity and quality of service, but it needs to be consolidated and updated. There are also gaps in knowledge that require additional research. This project is intended to lay the groundwork for a comprehensive Transit Capacity and Quality of Service Manual and to produce an interim version. It will also contribute to the transit chapter of the year 2000 update of the Highway Capacity Manual and conduct new research to address the highest priority gaps in knowledge about transit capacity and quality of service.

The objectives of this research are to (1) define the content of a comprehensive Transit Capacity and Quality of Service Manual, (2) provide transit input to the Highway Capacity Manual 2000, (3) develop a prioritized research agenda for completing the Transit Capacity and Quality of Service Manual, (4) complete those portions of a Transit Capacity and Quality of Service Manual for which information is available and produce an interim document, and (5) conduct research on one or more high-priority research topics growing out of the research agenda.

Status: The project was completed on January 31, 1999. The project also prepared draft materials for transit-related Chapters 12 and 27 of the Year 2000 Highway Capacity Manual (HCM). These materials are being reviewed and finalized by the Transit Subcommittee of the TRB Committee on Highway Capacity and Quality of Service. TRB has formed a Transit Capacity and Quality of Service Task Force, which will eventually be responsible for the contents of the Transit Capacity and Quality of Service Manual just as the Highway Capacity Committee has long been responsible for the contents of the HCM. Highlights of the manual were published as TCRP Research Results Digest 35, which is available in portable document format (PDF). Double-click on the files below to access the report. (A free copy of the Adobe Acrobat Reader is available at https://www.adobe.com.)

TCRP Research Results Digest 35

Comments are welcome.

The Transit Capacity and Quality of Service Manual, First Edition,is available in portable document format (PDF). Double-click on the files below to access the report. (A free copy of the Adobe Acrobat Reader is available at www.adobe.com.) PLEASE NOTE: Due to the very large size of these files, it may take a long time--possibly more than 1 hour collectively--to download. We regret the inconvenience.
For a limited time, the manual is also available on CD-ROM for $25.00. Contact the TRB Publications Sales Office at 202/334-3213.

TCRP Web Document 6

Front matter, Table of Contents, Foreword, Part 1: Introduction and Concepts

Part 2: Bus Transit Capacity

Part 3: Rail Transit Capacity

Part 4: Terminal Capacity

Part 5: Quality of Service, Part 6: Glossary