National Inventory of Specialty Lanes and Highways: Technical Report

Chapter 1. Overview of Specialty Lanes and Highways

Transportation agencies across the country have long grappled with the challenge of providing mobility options for travelers in high-demand, congested, or constrained travel corridors. Agencies at the Federal, State, metropolitan, and local levels have responded with a variety of techniques and approaches to improve traffic flow, enhance mobility, and provide travel options. The methods go beyond traditional roads and freeways and involve the implementation of specialty lanes and highways—facilities with unique operational rules or tolling (e.g., congestion pricing) that provide access for select user groups who meet the qualifications. These targeted user groups usually consist of carpools, vanpools, transit buses, alternatively fueled vehicles (e.g., biofuels, ethanol, solar, and electric), single-occupant vehicles, and trucks. The types of specialty lanes and highways can consist of managed lanes, toll roads, turnpikes, and facilities with active traffic and demand management (ATDM). Some of these special lanes receive oversight or permissions granted to facilities on the Federal highway system, and others are managed by States, counties, and private concessioners.

This document’s only purpose is to compile a one-stop listing of ten types of specialty lanes that supplement our Nation’s general purpose highways, including even some privately-owned facilities not under Federal oversight, for the purpose of creating, in effect, a utility desk reference.

The project team compiled and aggregated raw statistics of highways containing lanes that are not effectively general-purpose (GP) lanes. The main questions this report seeks to answer are:

• How many of these specialty lanes exist?
• What types of special services do they offer?
• Where are they located?

Managed lanes are described and defined in FHWA’s “Managed Lanes: A Primer” (FHWA-HOP-05-031) as “highway facilities or a set of lanes where operational strategies are proactively implemented and managed in response to changing conditions.” For purposes of this document, specialty lanes or managed lanes are lanes that are not GP lanes on America’s highways, or informally, “everything else,” exclusive of ramps, auxiliary lanes, and common shoulders. Specialty lane characteristics include access control via price (e.g., tolls), vehicle eligibility (e.g., occupancy or permits), or time of day (e.g., peak-hour reversible lanes). The project team primarily considered free-flowing facilities on freeway corridors, and not arterials.

For the purposes of providing the reader with a starting list of peer experts, we identify California, Washington, Virginia, Texas, Florida, Minnesota, and Georgia, as states that have placed significant focus on research and deployment of managed facilities, i.e., not inclusive of toll roads. Not coincidentally, these States have the most number of managed facilities.

A few types of facilities were not included in this list, primarily because those roads were effectively static in their purpose and not proactively dynamic in managing traffic. Specifically,  the following types of roads did not make the list:

• Roadways with all lanes that switch from one direction during the morning to the opposite direction during the afternoon, according to weekday commute patterns.
• Local roads in urban areas (e.g., downtown) that have a reversible center lane(s) to favor weekday inbound or outbound peaks.
• Roads that were—or are—temporarily re-deployed for either relief or secondary access during occasional special events, factory shifts, holidays, or unique public events, like parades or galas.

Project Scope and Objectives

The objectives of this project were to research, compile, and aggregate a national clearinghouse inventory (lists) of specialty lanes and highways that are not merely general in purpose, and any known planned facilities, as of the target publish date of this document. The inventory is not intended to provide any subjective commentary or synopsis of the merits, challenges, controversies, or any other discourse on the effectiveness of specialty lanes and highways. This document aims to serve as a reference-only for transportation agencies and practitioners who work with specialty lanes.

Need for an Inventory of Specialty Lanes and Highways

The last inventory by the FHWA occurred in 2007, as part of the FHWA HOV Pooled Fund Study, so an updated inventory is needed. This latest effort compiles more data elements and facility information to be useful to a wide array of audiences, including facility users, practitioners, and state and regional highway authorities.

Structure of Report

The report consists of four chapters followed by an appendix that details inventory information for each State.

• Chapter 1: Overview of Specialty Lanes and Highways: This chapter provides the reader with background and context about what specialty lanes are and how they are used in the United States. This includes a brief history and some photographs of facility types.
• Chapter 2: Information-Gathering Approach: This chapter explains the project team’s methodology in gathering the data necessary to produce an inventory of specialty lanes in the United States. This includes information on data sources, data validation techniques with engagement of regional experts, and information on the expert review panel, which helped to guide the report’s inventory schema and provided key observations and input for major task milestones.
• Chapter 3: Inventory of Specialty Lanes and Highways: This chapter summarizes information for the inventory. This includes aggregated information based on specialty lane facility type, distribution among states by number of facilities, States with the most specialty lane facility lane-miles, and so forth. This chapter is helpful for gaining quick insights into the overall state of specialty lane facilities in the United States.
• Chapter 4: Conclusion and Acknowledgements: This chapter explains some of the insights and observations gathered by the research team and the expert review panel.
• Appendix: The appendix contains detailed inventory information for each State and by each facility type.

Types of Managed Lane Facilities

The inventory divides the facilities based on their operational attributes, such as pricing, vehicle eligibility, and passenger occupancy eligibility permissions.

Table 2 indicates whether the facility type has tolling. The following sections describe the facilities in more detail.

Note: There may be singular exceptions to these general criteria.

High-Occupancy Vehicle (HOV)

An HOV lane or facility is one of the earliest and most common types of managed lane facilities; in fact, HOV lanes may be called the forerunners of all managed lanes. The first one was the Shirley Highway busway in Northern Virginia in 1969, which was later expanded to include carpools in 1973 (Chang, et al, 2008). HOV facilities provide access for carpools, vanpools, transit, and other eligible vehicles, such as, special-permit allowances like electric vehicles. The important distinction between HOV lanes and other specialty lanes is that vehicles are not assessed tolls to enter the specialty lanes from the general-purpose lanes. Two HOV lanes, however, do operate on toll roads: the Dulles Toll Road in Northern Virginia and the SR 520 Bridge in Washington State. For these two facilities, drivers pay a toll to enter the limited access corridor, but they do not pay an extra toll to enter the HOV lanes. For carpools, the eligibility conditions vary depending on the corridor. Some facilities allow vehicles for two or more occupants (HOV 2+). Other facilities require three or more occupants (HOV 3+). A large proportion of these facilities are single lanes and are situated parallel to the GP lanes. These lanes have separation from the GP lanes by a buffer or a permanent barrier and have access at the endpoints or intermediate access points along the corridor. Figure 1 shows an example of a sign for an HOV facility.

Source: Texas A&M Transportation Institute
Figure 1. Photo. High-Occupancy Vehicle Lane Sign in Nashville, TN.

High-Occupancy Toll (HOT)

A high-occupancy toll (HOT) facility can be understood as an HOV “plus” facility; at its core, it is an HOV facility, but it also allows lesser-occupant vehicles (e.g., single-occupant vehicle or two-person carpools, depending on the eligibility) to use the facility by paying a toll. The first HOT lanes were developed in 1995 and 1996 in California, on SR-91 in Orange County, and on I-15 in San Diego, respectively. Many HOT facilities were built with federal congestion mitigation and air quality (CMAQ) funding, which mandates that the carpools continue to use the facility toll-free. However, some facilities, perhaps under differing legislation, may provide discounted toll rates to HOVs during peak periods. For carpools, the eligibility conditions vary by every HOT facility. Most facilities allow HOV 2+ or HOV 3+. Many agencies converted former HOV lanes into HOT lanes, usually to take advantage of any excess capacity, but as mentioned, they must abide by CMAQ tenets. Figure 2 shows an example of a HOT lane.

Source: Texas A&M Transportation Institute
Figure 2. Photo. High-Occupancy Toll Facility, I-25 Express Lanes in Denver, CO.

Express Toll Lane (ETL)

An express toll lane (ETL) is a specialty lane that regulates access using all-electronic tolling. Generally speaking, all vehicles receive a toll charge as they enter the facility and/or pass toll gantries; the amount of toll is tied to the length of the trip. These facilities are not mandated to exempt HOVs from paying a toll, but a small portion of them may allow HOV discounts or may allow registered vanpools and transit vehicles to travel toll-free, as an incentive or reward to those community programs.  Figure 3 shows an example of an entry point to an ETL. Figure 4 shows an example of a buffer-separated ETL and GP lanes.

Source: Texas A&M Transportation Institute
Figure 3. Photo. Entry Point to an Express Lane Facility in Dallas, TX.

Source: Orange County Transportation Authority
Figure 4. Photo. Buffer-Separated Express and General-Purpose Lanes in Orange County, CA.

Non-toll Express Lane (NTEL)

A non-toll express lane (NTEL) is a specialty lane that provides a long distance bypass without charging a toll. The distinction here is that there are no tolls, but drivers might choose this lane as a means of bypassing clogged local exits; i.e., a non-tolled fast lane as it were. Generally, these facilities provide some type of physical separation, whether through the use of a striped buffer, barrier, or physical separation from the GP lanes. An example is the I-80 Express lane in New Jersey. It provides an NTEL that limits access to only a select few exits.  Travelers who want to use midpoint exits have to leave the express lanes and use the local lanes to access mid-point exits. In summary, such facilities allow drivers to bypass local traffic. The benefit in time is gained by avoiding the congestion created by the weaving and confluence of locally travelling vehicles.

Toll Road

A toll road may also be known as a turnpike, or commonly, a “for pay” highway. The distinction here is that, generally speaking, these roads do not parallel a general-purpose highway as an HOV or HOT lane would, which is to say, they do not offer a motorist a managed lane option-trip of a same-numbered adjacent highway. Many toll roads/turnpikes were built prior to the establishment of the Federal highway system and they are operated by states or turnpike commissions; for example, the Pennsylvania Turnpike is operated by the Pennsylvania Turnpike Commission. Toll roads have different types of payment mechanisms:

• Open: all vehicles stop at specific locations along the road and pay the toll.
• Closed: vehicles pay tolls only at the start or the exit of the facility.
• Open road systems: electronic tolling systems at strategic locations can be situated anywhere in the facility.

For tolled bridge facilities, drivers are required to pay a toll at the entry of the facility. This report includes both toll roads and toll bridges in the toll category. Figure 5 shows an example of a tollbooth facility.

Source: Texas A&M Transportation Institute
Figure 5. Photo. Payment Options at a Toll Booth.

Private agencies and companies also own and operate tolled facilities in the United States, beyond the number of State departments of transportation and other governmental entities.

Truck-Only Lane (TL)

A truck-only lane (TL) herein is a truck-only dedicated facility, and not merely a truck “passing” lane or slow(er) lane on a regular highway, nor is it a climbing lane or a downgrade lane positioned on a steep grade. A truck-only facility intends to separate heavy freight-carrying trucks from passenger vehicles on level-graded facilities, reducing safety conflicts by eliminating mixed flow operation between those vehicle classes. Presently, California has the only five known operational truck-only lane facilities in the U.S.; two I-5 truck-only lanes in Los Angeles County, the I-15 truck-only lanes in San Bernardino County, the SR-60 truck-only lane in Riverside County, and the I-5 truck-only lanes in Kern County. As a point of reference, after constructing the new I-5 alignment in L.A. County over 30 years ago, the original alignment was kept for the truck-only lanes. Green guide signs encourage passenger vehicles to continue travelling in the main travel lanes and to not use the truck-only lanes. However, since green guide signs are not enforceable, passenger cars are not entirely prohibited from using the truck-only lanes. All facilities are owned and operated by the California Department of Transportation (Caltrans).

At the time of this report, the Georgia Department of Transportation (GDOT) is planning a truck-only facility with an expected construction start date of 2025.  The “I-75 Commercial Lanes” is proposed to be a 38-mile facility that will run northbound-only in parallel to the existing I-75 highway from approximately Macon to McDonough, near the southeast portion of the Atlanta metropolitan region.  The purpose of the facility is to separate the heavy vehicle freight traffic to Atlanta that generally originates from the Georgia ports of Brunswick and Savannah. The facility will have a few local exits, but  GDOT anticipates a very high percentage of freight traffic will make the entire 38-mile trip. The Georgia I-75 Commercial Lanes are not included in the National Inventory, because only operational facilities are listed in these data.

Bus-Only Lane, Busway, or Transitway (BL)

A bus-only lane (BL), busway, or transitway is dedicated for use by buses and transit vehicles only. This facility is designed to improve bus speeds and travel time reliability in congested areas. Many cities have bus-only lanes on arterials, but the inventory only lists facilities that are present on freeway and limited-access corridors. For example, New Jersey has an exclusive BL facility along I-495, connecting the New Jersey Turnpike to the Lincoln Tunnel.

Bus-on-Shoulder (BOS)

A bus-on-shoulder (BOS) facility permits buses to use the shoulders to avoid congestion along the roadway. Generally, buses may use the shoulder lane only when the mainline traffic speed goes below a specific threshold. This facility type promotes transit ridership by increasing reliability for bus routes in congested corridors. Shoulders are improved to handle the conditions and signage displays the rules. As an example of how BOS operates, in Minnesota, congestion (defined by speeds) must pre-exist, so almost by rote, BOS occurs during recurring congestion periods. The maximum speed of the buses on the shoulder is 35 mph and buses are not allowed to exceed traffic by more than 15 mph, except for special circumstances. Buses may “dead-head” (operate empty) and must yield to vehicles exiting and entering at interchanges. Motorists have a duty to obey some rules too, and can be ticketed, but the professional bus drivers are deemed to have the best advantage to avoid conflicts and accidents. The decades-long existence of BOS in Europe and in 12 U.S. States attests to their efficacy. Figure 6 presents an example of a BOS lane.

Source: Federal Highway Administration
Figure 6. Photo. Bus-on-Shoulder Lane.

Dynamic Part-Time Shoulder Use (D-PTSU)

Dynamic part-time shoulder use (D-PTSU) allows vehicles to temporarily use the shoulder lanes, as indicated by highway operators. The opening of the part-time shoulder usually occurs when the mainlines (or general purpose, i.e., GP lanes) experience traffic congestion and an operator in a traffic management center opens the shoulder for use. Typically, dynamic signs at the entry of the shoulder display open/closed status for informing users when the lanes are open.

Static Part-Time Shoulder Use (S-PTSU)

Static part-time shoulder use (S-PTSU) allows vehicles to use shoulder lanes during a pre-established schedule. Generally, a S-PTSU facility opens during typical recurrent weekday morning and afternoon peak periods, usually when traffic congestion is present on the adjoining lanes.

History of Specialty Lanes

The rate of vehicular growth has been increasing, but the highway infrastructure to serve the desired capacity has not kept pace with traffic growth. Different operational and management strategies have been tried to accommodate peak-hour traffic. Outside of toll roads (e.g., early cross-state wagon-and carriage trails, and later, state-financed turnpikes) the introduction of the concept of managed lanes began in the 1970s as a means to increase freeway efficiency. Figure 7 shows the introduction of various managed lane facilities over time, and the following sections describe them in more detail.

Source: Texas A&M Transportation Institute
Figure 7. Illustration. History of Managed Lane Facilities.

Toll Road

Historically, toll road facilities were an early form of specialty roadway facilities. A toll road is a publicly or privately managed facility that collects tolls from users. Tolls can either be collected manually at toll booths or electronically using a transponder; it depends on the evolution of each particular facility. The first engineered and compacted road in the United States was built in 1795 and was designed for horse-drawn wagons. The “Philadelphia and Lancaster Turnpike” in Pennsylvania had ten “toll houses” thereby concurrently denoting it as the first toll road. Over time, many states and/or private developers built their own toll roads or turnpikes. Some of these agencies were eventually absorbed by the states; others continue today as any number of turnpike commissions, state tolling authorities, quasi-governmental agencies, or interstate compacts. (Source: U.S. DOT/FHWA, search: “Highway History.)

Bus-Only Lane

The first application of managed lanes consisted of a bus-only lane outside of Washington, DC, in Northern Virginia; the Henry G. Shirley Memorial Highway in 1969 (Chang et al., 2008). The ridership on the buses increased steadily, but the bus capacity remained underutilized. In December 1973, transportation planners opened the lanes to carpools and vanpools (Turnbull, 1990).

High-Occupancy Vehicle Lane

During the 1970s, HOV facilities became a significant alternative to fulfill the peak demand needs and were increasingly considered by planners in highway improvement projects. Turnbull (1990) performed an overall assessment of six HOV facilities and found various factors that led to the development of HOV projects. The study categorized the HOV projects based on features such as planning, decision making, and institutional arrangements, and examined the reasons behind the development of these projects. In another study, Dahlgren (1994) studied the benefits of adding an HOV lane instead of a GP lane. His study assumed that car users select HOV lanes only when there is a time differential between an HOV and GP lane. The study found the addition of the HOV lane to be efficient if the proportion of HOVs reached 20 percent.

Part-Time Shoulder Use Lane

During peak traffic periods, existing road infrastructure may be unable to serve the excess demand. The FHWA, in coordination with State and local departments of transportation (DOTs), works to maximize the efficiency of existing infrastructure through various strategies. Transportation systems management and operations (TSMO) plans strategize ways to restore and maintain the existing transportation system during peak demand.

Part-time shoulder use (PTSU) is one of the TSMO strategies that involve the temporary use of shoulder lanes during certain hours of the day. It is one form of active traffic management and a very cost-effective solution to congestion problems. State DOTs and various local agencies have implemented part-time shoulder use to address peak demand and improve transportation performance. This strategy is modified based on requirements such as the location of the shoulder (left or right), vehicle use (bus or HOV), and schedule (FHWA 15-23, 2016). Except for temporary use during peak time, these shoulder lanes, of course, serve as refuge/emergency purposes. A great deal of concern initially arose over the efficacy of using “breakdown” lanes for active traffic. In the right context, PTSU facilities can be operated safely (FHWA 15-23, 2016). One example of a recently opened PTSU facility is the I-670 ‘SmartLane’ in the Columbus, Ohio metropolitan region that started operating in October 2019. During the first couple of months of operation, the Ohio Department of Transportation observed a significant reduction in mainline crashes that were previously the result of stop and go traffic.

High-Occupancy Toll Lane

Fielding and Klein (1993) first introduced the concept of HOT lanes. In this type of priced lane, typically single occupant vehicles (SOVs) that do not meet HOV2+ or greater requirements pay a toll, and higher-occupancy vehicles (usually either two or more occupants or three or more occupants) remain exempted from paying the toll. These lanes can use underutilized HOV lane capacity and may also serve as a revenue source for meeting other regional transport needs (Varaiya, 2007). HOT lane facilities are signed as “Express” lanes per mandate by the Manual of Uniform Control Devices (MUTCD 2G.16.05). There can be confusion, as many highway engineers and the public use the coloquial “expresslanes” as a wide, catch-all term, but technically “Express Lanes,” for example, are not HOT lanes. The first HOT lane facility opened as the “91 Express Lanes” (thus, perhaps, establishing the signing precedent) in California in 1995. This facility has two primary lanes in each direction and is separated from the main lines with plastic lane markers. As noted above, the functionality of “Express Lanes” is different from that of HOT lanes. Thus, the reader is cautioned not to confuse the purpose with the vernacular.

HOT lane facilities follow open road tolling to reduce time delay. In this system, users are charged a toll by the electronic toll system. In practice, each vehicle installs a toll tag, which is read by the overhead antenna, and the system deducts the toll amount from the user’s account. Users who do not have a tag can pay the toll via mail within a specified time period. Most of the HOT facilities have static or fixed toll rates throughout the day. A few HOT lanes, such as the I-66 Express Lanes in Virginia, have dynamic rates where toll rates change based on the time of day and traffic flow through the section. Usually, during morning and evening peak periods, toll rates increase with a rise in road traffic users, and rates are set according to a dynamic pricing formula.

Express Lane

“Express Lanes” are intended to provide a more reliable trip than congested general-purpose lanes.  This type of facility targets, and benefits, longer trips. They have fewer entry and exit points as a means to bypass the confluence of local traffic lanes. Users can access or exit the facility at predetermined locations only. Express lane facilities can be tolled or non-tolled lanes, described as ETL and NTEL, respectively. In ETL facilities, all users pay the toll, and no exemption is given to any user, excepting perhaps reduced tolls as incentives to HOVs, for example. The 595 Express Lanes in Florida is a good example of an ETL facility. These lanes are parallel to the GP lanes and are generally located on the leftmost section in each direction. The GP lanes are separated by a concrete barrier to allow vehicles to move quickly and safely on the express lanes. The 595 ETLs offer a commuter incentive program by pre-registration, which rewards local HOVs with reduced tolls. Occasional HOVs pay the full toll. The Bergen-Passaic Expressway, is an example of an NTEL facility; it was constructed to alleviate (remove, via bypass of local exits) congested traffic on NJ 4 (State Road in New Jersey).