An Agency Guide on How to Establish Localized Congestion Mitigation Programs

1.0 Introduction

1.1 Purpose of the Guidance Document

This guidance document provides guidelines that can be used by state DOTs and local transportation agencies in developing a Localized Bottleneck Reduction (LBR) Program. It covers all aspects of designing and implementing an LBR program, from establishing the institutional structure required to support an LBR program to bottleneck identification, improvement, evaluation, and public outreach. The guidance document was developed based on best practices used by state and local agencies.

1.2 How to Use this Document

Target Audiences

This document is designed for state, regional, and local transportation agencies that are focused on mitigating operational causes of bottlenecks. These causes include a wide variety of issues from poorly functioning merges to poor signal progression throughout a corridor. This document targets planners as well as traffic, safety, and design engineers. Operations and Maintenance staff will also find this document as a useful way to begin addressing bottleneck issues in a comprehensive and coordinated way. The document includes a discussion on how best to start a LBR program in your agency. It includes case studies and a series of templates, which the reader can use in starting their own program.

Document Structure and Content

This guidance document includes the following sections:

• Section 1.0 – Introduction. This section provides background information on traffic bottlenecks and describes how FHWA is addressing bottlenecks through their LBR Program.
• Section 2.0 – How to Structure a Localized Bottleneck Reduction Improvement Program. This section provides guidance to state and local agencies in structuring a program to address localized bottleneck problems. It describes agency roles and responsibilities, options for structuring the program, and factors for success. A self-assessment tool is also provided to assist agencies in establishing where they currently stand with regard to implementing a bottleneck program.
• Section 3.0 – Resources. This section provides case study examples of successful bottleneck programs across the United States, including best practice examples in the areas of performance measurement, bottleneck analysis, and project prioritization.

1.3 Background

Bottlenecks: A Definition

The FHWA estimates that 40 percent of all congestion nationwide can be attributed to recurring congestion; some of it “mega” – wherein, entire regions or large facilities (e.g., interchanges or corridors) are overwhelmed by seemingly unceasing traffic demand – and some of it “subordinate” – locations on the highway system where periodic volume surges temporarily overwhelm the physical capacity of the roadway. During off-peak hours, the subordinate locations operate sufficiently and safely for the conditions. These recurring “localized” bottlenecks are those encountered in our everyday commutes, and are characterized as being relatively predictable in cause, location, time of day, and approximate duration. Nonrecurring bottlenecks, on the other hand, are caused by random events such as crashes, inclement weather, and even “planned” events such as work zones and special events.

This guidance document focuses on “localized” recurring bottlenecks (i.e., point-specific or short corridors of congestion due to decision points such as on- and off-ramps, merge areas, weave areas, lane drops, tollbooth areas, and traffic areas); or design constraints such as curves, climbs, underpasses, and narrow or nonexistent shoulders. Mega-bottlenecks or those occurring due to systemic congestion are not meant to be covered by the scope of this guidance.

For a bottleneck to be “localized,” the factors causing the bottleneck ideally should not influence upon, or be influenced by, any other part of the transportation system. As a practical measure, the LBR program recommends considering the closest upstream and downstream decision points as either impacting “to” or impacting “from” the subject location, respectively. Anything much beyond that reach might be considered more than “localized.” One exception might be collector-distributor lanes that would almost certainly run through two or more on- or off-ramps. Such a “system” can be considered as a larger, localized condition. Otherwise, recurring, localized bottlenecks generally occur at the following locations:

• A lane drop, particularly mid-segment where one or more traffic lanes ends. These typically occur at bridge crossings and in work zones. In large urban areas, a lane drop might occur at jurisdictional boundaries just outside the metropolitan area. Ideally, lane drops should be located at exit ramps where there is a large volume of exiting traffic.
• A weaving area, where traffic must merge across one or more lanes to access entry or exit ramps. Bottleneck conditions are worsened by complex or insufficient weaving design.
• Freeway on-ramps, where traffic from local streets merge onto a freeway. Bottleneck conditions are worsened on freeway on-ramps without auxiliary lanes, short acceleration ramps, or where there are multiple on-ramps in close proximity.
• Freeway exit ramps, which are diverging areas where traffic leaves a freeway. Bottleneck conditions are worsened on freeway exit ramps that have a short ramp length, traffic signal deficiencies at the ramp terminal intersection, or other conditions that may cause ramp queues to back up onto freeway main lanes. Bottlenecks could also occur when a freeway exit ramp shares an auxiliary lane with an upstream on-ramp, particularly when there are large volumes of entering and exiting traffic.
• Freeway-to-freeway interchanges, which are special cases on on-ramps where flow from one freeway is directed to another. These are typically the most severe form of physical bottlenecks because of the high traffic volumes involved.
• Abrupt changes in highway alignment, which occur at sharp curves and hills and cause drivers to slow down either because of safety concerns or because their vehicles cannot maintain speed on upgrades. Another example of this type of bottleneck is in work zones where lanes may be redirected or even slightly shifted during construction.
• Low clearance structures, such as tunnels and underpasses. Drivers slow to use extra caution, or overload bypass routes. Even sufficiently tall clearances could cause bottlenecks if optical illusion causes a structure to appear lower than it really is, causing drivers to slow down.
• Lane narrowing, caused by either narrow travel lanes or narrow or nonexistent shoulders.
• Intended interruptions to traffic flow that are necessary to manage overall system operations. Traffic signals, freeway ramp meters, and tollbooths can all contribute to disruptions in traffic flow.

A detailed discussion on bottleneck characteristics is provided in FHWA Publication FHWA-HOP-09-037, Recurring Traffic Bottlenecks: A Primer – Focus on Low-Cost Operational Improvements.

Bottlenecks: A History

Timeline of National Bottleneck Activities

Over the past several years, transportation professionals have come to realize that highway bottlenecks demand special attention. Several national studies have highlighted bottlenecks as a major congestion problem in urban areas. These studies have raised the level of awareness about bottlenecks as a problem, warranting that they be treated as a significant part of the congestion problem.

One of the LBR tenets is “a bottleneck is congestion, but congestion is not always just a bottleneck.” This means that a bottleneck (or chokepoint) is merely a subset of the larger congestion pie. However, that “subset” is now realized to be a uniquely impacting (and increasingly growing) genre of congestion; namely, that it is subordinate locations along a highway that need to be fixed, and not necessarily the knee-jerk expectation to rebuild the entire facility. Granted, in some cases, an aging or clearly capacity-deficient facility may need to be replaced. But in this age of budget constraints and economizing, one or two corrections to inefficient subordinate locations on a facility may be all that is needed to improve the condition.

The American Highway Users Alliance (AHUA) conducted studies of the nation’s urban bottlenecks in 1999 and 2004. The studies produced rankings of the worst bottlenecks in terms of total delay to travelers and discussed what was being done to fix the problems at locations where specific improvements had been scheduled. The studies found that nearly all of the worst bottlenecks are major freeway-to-freeway interchanges in large urban areas, but many smaller bottlenecks were surprisingly impacting as well. The 2004 study updated the 1999 rankings and discussed three bottleneck improvement success stories – bottlenecks identified in 1999 that were subsequently improved or well under construction; the clear message being that mitigations can be realized.

States and regions are beginning to recognize the significance of bottlenecks as well. The Ohio Department of Transportation completed a study of freight (trucking) bottlenecks, and the Interstate 95 Corridor Coalition is undertaking a study of all potential bottlenecks in Coalition states. The Atlanta Regional Commission has defined bottlenecks as a specific portion of their Congestion Management Process and is identifying regional and local bottlenecks in their network.

In 2002, the Texas Transportation Institute compiled a database of before/after measurements of selected Texas DOT initiatives to remove bottlenecks and improve operations on urban freeways. The benefit/cost ratios and reductions in crash rates observed at these locations provided valuable insight regarding the effectiveness of various bottleneck reduction strategies over time.

More recently, an effort by a private data provider, Inrix, also identified the nation’s worst bottlenecks (Table 1.1). Whereas previous bottleneck identification efforts were based on analytic procedures using traffic volumes and capacity data, Inrix’s approach uses data assembled by them from a variety of sources. As direct travel time measurements become more common and better refined, the science of bottleneck identification and performance will improve.

Table 1.1 Inrix 2009 Annual Report Worst Traffic Bottlenecks

Rank		CBSA (Pop Rank)	Road/Direction	Segment/Interchange	County	State	Length (Miles)	Hours of Congestion	Average Speed While Congested
2009	2008
1	1	New York(1)	Cross Bronx Expy WB/I-95 SB	Bronx River Pkwy/Exit 4B	Bronx	NY	0.35	94	11.4
2	7	Chicago (3)	Dan Ryan Expy/I-90/I-94 WB	Canalport Avenue/Cermak Road/Exit 53	Cook	IL	0.4	83	11.1
3	5	New York (1)	Cross Bronx Expy WB/I-95 SB	I-895/Sheridan Expy/Exit 4A	Bronx	NY	0.51	95	12
4	2	New York (1)	Cross Bronx Expy WB/I-95 SB	White Plains Road/Exit 5	Bronx	NY	0.28	86	11.9
5	3	New York (1)	Harlem River Drive SB	3rd Avenue	New York	NY	0.16	77	9.6
6	62	New Haven (58)	I-91 SB	Hamilton Street/Exit 2	New Haven	CT	0.22	76	12.8
7	13	Los Angeles (2)	Hollywood Fwy/U.S. 101 NB	Los Angeles Street	Los Angeles	CA	0.1	85	14
8	24	Chicago (3)	Dan Ryan Expy/I-90/I-94 WB	18th Street/Exit 52C	Cook	IL	0.41	83	13.7
9	11	New York (1)	Cross Bronx Expy WB/I-95 SB	Westchester Avenue/Exit 5	Bronx	NY	1.15	76	12.8
10	26	Chicago (3)	Dan Ryan Expy/I-90/I-94 WB	Ruble Street/Exit 52B	Cook	IL	0.12	86	14.7
11	10	Los Angeles (2)	Hollywood Fwy/U.S. 101 SB	Vermont Avenue	Los Angeles	CA	0.62	82	15.4
12	16	Los Angeles (2)	Hollywood Fwy/U.S. 101 NB	Alameda Street	Los Angeles	CA	0.27	82	14
13	29	Chicago (3)	Dan Ryan Expy/I-90/I-94 WB	Roosevelt Road	Cook	IL	0.22	86	16.2
14	9	New York (1)	Harlem River Drive SB	2nd Avenue/125th Street/Exit 19	New York	NY	0.22	75	11.1
15	6	New York (1)	Van Wyck Expy/I-678 NB	Liberty Avenue/Exit 4	Queens	NY	0.52	61	11.7
16	36	Los Angeles (2)	Pasadena Fwy/CA 110 NB	Sunset Boulevard/Exit 24A	Los Angeles	CA	0.21	45	10.4
17	12	New York (1)	Van Wyck Expy/I-678 NB	Hillside Avenue/Exit 6	Queens	NY	0.12	71	14
18	8	Chicago (3)	Eisenhower Expy/I-290 EB	U.S. 20/U.S. 45/U.S. 12/Exit 17	Cook	IL	0.99	62	14.3
19	19	Los Angeles (2)	Hollywood Fwy/U.S. 101 NB	Spring Street	Los Angeles	CA	0.14	82	16.1
20	17	New York (1)	I-95 NB	U.S. 9/U.S. 1/U.S. 46/Exit 72	Bergen	NJ	0.42	66	11.3

FHWA Involvement

FHWA’s first effort related to bottlenecks was in the freight (trucking) arena. In 2005, using the AHUA studies as a starting point, FHWA conducted an assessment of the impacts that highway bottlenecks have on truck freight shipments. Bottlenecks outside of urban areas were also considered (e.g., steep grades). A major finding of this study was that in terms of total delay, the urban bottlenecks – typically thought of as a commuter-related problem – are also major sources of truck delay. In 2009, in partnership with the American Transportation Research Institute (ATRI), FHWA conducted an in-depth analysis to produce a congestion severity ranking for 100 freight significant highway interchanges. The rankings can be used by both public and private sector stakeholders to better identify transportation system deficiencies and to assist in logistics and routing decisions. ATRI and FHWA will continue to monitor these locations on an annual basis.

In preparing the FY 2006 Strategic Implementation Plan (SIP), the FHWA Operations Leadership Council discussed the need for a national strategy to address bottlenecks and requested each Division office to identify bottleneck locations in their state. The responses ranged from mega bottlenecks encompassing multi-interchange corridors to point-specific localized chokepoints. FHWA initiated the Localized Bottleneck Reduction (LBR) Program in 2007 to raise awareness of point-specific localized bottlenecks at the state level and promote low-cost, quick-to-implement geometric and operational improvements to address recurring chokepoints. One of the first activities of the LBR Program was a survey of FHWA Division office personnel to obtain state best practices in bottleneck identification, assessment, countermeasures, and evaluation, including examples of overcoming unique challenges such as strategies requiring a design exception, cooperation among several departments, creative funding, and public perceptions. A compendium of state best practices was developed from these responses. More details on the LBR Program are provided in Section 1.4.

Previous Similar Bottleneck Efforts

TOPICS

The Federal-Aid Highway Act of 1968 established the Traffic Operations Program to Improve Capacity and Safety (TOPICS). The program authorized $200M in Federal matching to fund projects designed to reduce traffic congestion and facilitate the flow of traffic in urban areas. Although candidate projects were not planned to the same scale as regional planning processes (Weiner, Edward, Urban Transportation Planning in the United States: An Historical Overview. Revised and Expanded Edition. Praeger Publishers, Westport, Connecticut, 1999.), TOPICS was a landmark program in demonstrating the concepts and effectiveness of traffic management practices.

1.4 The Localized Bottleneck Reduction Program

FHWA’s Localized Bottleneck Reduction (LBR) Program promotes operational and low-cost bottleneck mitigation strategies to improve mobility. Managed by the Office of Operations, the program serves to bring attention to the root causes, impacts, and potential solutions to traffic chokepoints that are recurring events; ones that are wholly the result of operational influences. This is “good and bad” news in the sense that design influences can always be corrected, but some corrections may be cost-prohibitive in terms of direct construction costs or indirect right-of-way impacts. Regardless, a significant amount of locations can be corrected for relatively low-cost and/or low physical impact. In any case, the goal of the program is to raise awareness of bottlenecks at the state level and promote low-cost, quick-to-implement geometric and operational improvements to address recurring chokepoints. The LBR Program has several activities either completed or underway, including:

• This guidance document, which provides guiding principles and concepts common to low-cost operational improvement programs to assist states in adopting a programmatic approach to addressing traffic congestion at bottlenecks.
• Traffic Analysis Toolbox Volume X: Localized Bottleneck Congestion Analysis – Focusing on What Analysis Tools are Available, Necessary, and Productive for Localized Congestion Remediation. This document provides guidance on analysis tools and data inputs required to analyze the specific genre of localized congestion problems.
• Recurring Traffic Bottlenecks: A Primer – Focus on Low-Cost Operational Improvements. This Primer is the “face” of the program. It provides an overview of the wide range of operational and low-cost strategies available to reduce congestion at bottlenecks.
• A compendium of state best practices in bottleneck identification, assessment, countermeasures, and evaluation, including how bottlenecks are treated in the annual planning and programming processes.
• Localized Bottleneck Reduction Regional Workshops. Regional workshops for state and local agencies to learn and share information on localized bottleneck reduction strategies and how they can be incorporated into state and local planning processes.
• Many of the items listed above can be found at the FHWA bottleneck web site, which can be found at the FHWA Office of Operations web site.

Additional guidance documents are forthcoming that are aimed at agencies and personnel who have first responsibility to address bottleneck congestion locations.