An Expanded Functional Classification System for Highways and Streets

A recent survey conducted by the National Committee on Uniform Traffic Control Devices Task Force explored current and potential approaches to the setting of posted speed limits. The survey was distributed in the spring of 2018 and gathered 740 responses. The survey found that many states and local agencies have their own laws or criteria for the setting of speed limits (many are very detailed). Professionals who perform posted speed limit studies rarely only use the 85th percentile speed. It is clear from the survey that analysts who establish speed zones utilize many factors beyond the 85th percentile in their studies, including the context, that is, where the street is and what function it serves. The use of the 85th percentile for rural roads or interstate/freeways is different from urban streets (on urban streets, the 85th percentile plays a less significant role). The industry knowledge and use of USLIMITS2 are very limited. USLIMITS2 is a web-based tool designed to help practitioners set speed limits and is maintained by the Federal Highway Administration. Setting of reasonable speed zones requires consideration of many factors that are currently not well defined in the Manual on Uniform Traffic Control Devices (MUTCD). These factors are best defined as part of national guidance/research or local policy documents and do not need to be defined in the MUTCD as they can involve state/local interpretation.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Current Attitudes among Transportation Professionals with Respect to the Setting of Posted Speed Limits

Fitzpatrick¹,

McCourt

Das³

2019

“…The philosophy of complete streets, context-sensitive design, and context-sensitive solutions are examples of where the consideration of the roadway context is factored into the decision-making process. These ideals were also reinforced by the recent publication of a series of related NCHRP research reports that developed an expanded functional classification system, explored a performance-based design process, or advanced guidance on integrating safety and cost-effectiveness in design (4,(23)(24)(25).…”

Section: Selecting the Base Format For Sls-proceduresmentioning

confidence: 99%

“…The publication of NCHRP Research Report 855 An Expanded Functional Classification System for Highways and Streets during the early stages of NCHRP 17-76 outlined contexts beyond urban and rural and facilitated accommodation of modes other than personal vehicles (4). The timing of this report, along with the increased activity by states and cities in exploring alternative methods for setting posted speed limits (see following sections) provided the opportunity for the NCHRP 17-76 research team to better integrate consideration of context into a refined speed limit setting procedure.…”

mentioning

confidence: 99%

Considering Roadway Context in Setting Posted Speed Limits

Fitzpatrick

Das

Gates

et al. 2021

The National Cooperative Highway Research Program (NCHRP) Project 17-76 investigated factors that influence operating speed and safety through a review of the literature and an analysis of the relationships for speed, safety, and roadway characteristics on urban/suburban streets. That knowledge, along with a review of existing speed limit setting practices, was used to develop a Speed Limit Setting Procedure (SLS-Procedure) as well as a user manual to explain the SLS-Procedure. In addition, the SLS-Procedure was automated via a spreadsheet-based Speed Limit Setting Tool (SLS-Tool). These products will permit engineers to make informed decisions about the setting of speed limits. The SLS-Procedure is fact based and transparent, relying on a set of decision rules that consider both driver speed choice and safety associated with the roadway. The SLS-Procedure was designed to be applicable across different roadway types and contexts by having a set of unique decision rules for four combinations of roadway types and contexts: limited-access, undeveloped, developed, and full-access facilities. The SLS-Procedure uses the operating speed distribution as a starting point for the suggested speed limit, with the resulting suggested value based on consideration of roadway type, context, safety performance, and other characteristics.

“…FDOT adapted the measure thresholds using research and guidance from the CNU, the Institute of Transportation Engineers (ITE), state and regional agencies (8)(9)(10), and case studies of places throughout the state. While FDOT was developing its context classification system, parallel research efforts proposed similar measures, including NCHRP Research Report 855: An Expanded Functional Classification for Highways and Streets (11,12).…”

Section: Introductionmentioning

confidence: 99%

Almost Automating the Planner: Florida Department of Transportation’s Approach to Understanding Places through Context Classification

Kent¹,

Parlow

Chesna

et al. 2021

Context-based thinking is a transportation planning and design approach that aims to create infrastructure that serves diverse places and users. In Florida, context-based design is the approach Florida Department of Transportation (FDOT) has taken to implement its Statewide Complete Streets policy. FDOT intends to use the context of a roadway to better tailor design and planning solutions for the roadway, thereby putting the “right street in the right place.” To this end, FDOT developed a context classification system and guidance document for project corridors and has since applied the classification effort to the entire state road network. This paper shares a method that two FDOT districts, District One and District Five, used to accomplish their districtwide context classification efforts. The method leverages geographic information systems (GIS) to appropriately segment the road network, analyze connectivity, land use, and density measures, and evaluate the context classification for all state roads within each district. The resulting database is regularly updated using a GIS-based tool and serves as a rich source of information for FDOT and partner agency planners and designers.