1. Home
  2. TRID
  3. View Record
https://www.nationalacademies.org/trb/events

Conventional Level-of-Service Analysis, Thresholds, and Policies Get a Failing Grade

Many planners feel somewhat constrained by existing environmental practices that require jurisdictions to maintain a minimum level of service (LOS) for roadways. These requirements make infill, high-density, pedestrian-oriented, or transit-oriented development difficult to approve due to impacts that they may have to already-congested traffic circulation. The state of the practice for many jurisdictions is to require that transportation facilities, typically intersections, operate at, or better, than a designated LOS threshold, which is measured using average vehicular delay. Often, this policy results in mitigation requirements in the form of increased vehicular capacity at locations where a development may be expected to add traffic and degrade levels of service beneath these acceptable thresholds. While capacity expansion aimed at moving more cars and trucks through an intersection may reduce the average vehicular delay at an intersection, it may have a negative impact on other modes of transport such as pedestrians, bicycles, and transit. The goal of most local planning agencies with respect to transportation is primarily focused on the movement of people during commute hours, rather than the movement of vehicles. However, current practices treat all types of vehicles nearly equal such that delay imparted to a fully-occupied transit vehicle is weighted the same as delay to two single-occupant vehicles. In recognition of this bias, some agencies are exploring the use of a multimodal LOS aimed at improving person-capacity of transportation facilities that places an equal weight on modal impacts. In addition, attempts are underway to better define bicycle and pedestrian service levels and to account for land use considerations by examining the contextual appropriateness of capacity expansion. This paper will discuss the political challenges facing attempts to change current LOS policies, describe technical simulation tools to quantify delay-based impacts to modes other than private autos, and present a case study for recent multi-modal LOS planning efforts in Davis, California. The findings of this study demonstrate that current traffic simulation tools are capable of analyzing person-delay across multiple modes at intersections. This approach provides a complete picture of delay and how traffic control, geometric, or other intersection modifications will affect all intersection users. This advancement makes it possible to modify the traditional vehicle-based LOS policies used by local agencies to address the desired operating conditions of intersections or other facilities from the perspective of multiple modes.

Language

  • English

Media Info

  • Media Type: DVD
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 29p
  • Monograph Title: TRB 87th Annual Meeting Compendium of Papers DVD

Subject/Index Terms

Filing Info

  • Accession Number: 01088426
  • Record Type: Publication
  • Report/Paper Numbers: 08-0127
  • Files: TRIS, TRB
  • Created Date: Feb 25 2008 2:32PM