Sustainability, as it relates to transportation, supports transportation alternatives that encourage multimodal development and discourage the use of single occupant vehicles (SOVs). The success of these transportation alternatives becomes more and more critical as traffic congestion and its byproducts, such as air pollution, continue to increase as a rapid pace, and it goes hand in hand with land use policies that encourage alternative modes of transportation.

Managed lanes are one of the transportation alternatives to SOVs. They provide an opportunity to increase the maximum passenger throughput per lane significantly as compared to general-purpose lanes.

Overview of Managed Lanes

Managed lanes can be described as a lane or system of lanes designed and operated to improve roadway efficiency by maintaining high-speed travel, and providing for efficient person/vehicle travel, particularly during periods when the remainder of a roadway is congested.

Managed lanes are not a new concept; however. Limited-access freeways, express lanes, reversible lanes, toll facilities, and high-occupancy vehicle (HOV) lanes are all forms of managed lanes that have been around for decades. What is new is the application of technology that is taking managed lanes to new levels of sophistication, allowing better management to more users and lower costs.

Each transportation facility’s objectives determine the types of management strategies to be used and provide a benchmark against which success is measured. These objectives can relate to:

• Operations: Vehicle or person throughput or minimum speed targets
• Revenue: Revenue maximization or specific targets to retire capital construction debts
• Policy: Increasing carpool or transit mode share or facilitating movement of goods.

Management strategies, which can be operated and implemented individually and in combination depending on specific travel demand conditions, can be categorized according to their primary focus:

• Eligibility Definition. This technique designates travel to specific users by vehicle type (bus or truck) or occupancy requirement (2+ or 3+ carpool). Examples include transit-only lanes, truck lanes, and HOV lanes.
• Pricing. This adaptation of the traditional toll road is designed to manage demand through tolling so as to provide an assured level of service to users and potentially generate revenue. Priced managed lanes apply electronic tolling, and users are required to have transponders.
• Access Control. Access control techniques, such as express lanes, reversible lanes and ramps, can control and maintain vehicular throughput at a higher level of service.

Example Projects

Managed lanes involving pricing are relatively new, yet we have several examples.

Figure 1: Two views of SR-91 HOT lanes demonstrate that we are able to preserve free-flow conditions on the toll facility with the right pricing scheme.

Figure 2: New Jersey Turnpike in northern New Jersey—Dual Facilities.

SR-91, Orange County, California: HOV/Toll Express Lanes. All three strategies are used on this four-lane express facility along 16 km (10 miles) of the SR 91 freeway median (Figure 1). The roadway has only one entrance and exit point, and has a single electronic toll reader location with a separate bypass lane for 3+ HOVs, which travel for free. Other vehicles pay a graduated toll rate depending on time of day and space available.

The project has helped sustain a high level of mobility in a very environmentally sensitive corridor by promoting the following benefits:

• Increasing HOV and transit usage, thereby reducing the need for adding more lanes
• Increase average vehicle occupancies, thereby decreasing emissions
• Increasing overall corridor travel times, thereby providing economic and environmental benefits.
• Promoted revenue generation, thereby providing local agencies with additional investment funding for transit services that would not otherwise have been possible.

I-5 and I-90 Express Lanes, Seattle, Washington: Express Lanes. I-5 and I-90 provide express lanes built parallel to the highways to provide extra peak-direction capacity during commute hours. Both roadways operate as reversible facilities, running into Seattle during morning commute hours and away during afternoon. The hours of operation can be changed to accommodate special events.

Access is managed to promote quick transit and carpool movements into and out of downtown. Access is regulated through gates to promote HOV use and allow others on the freeway to use the express lanes outside the downtown ramps. Access control coupled with access preference to transit and carpools helps to manage traffic growth, reduce dependence on single occupant vehicles and promote better air quality in the Puget Sound region.

New Jersey Turnpike - Northern New Jersey: Dual Facilities. Between Interchanges 8A and 16E, the New Jersey Turnpike operates as a dual roadway with a designated bus/HOV lane in the outer “commercial truck” roadway barrel (Figure 2). This lane helps move more than 800 buses (30,000 commuters) during a typical morning peak period. The outer roadway can be preferentially managed separate from the inner roadway that is typically filled with single occupant commuters. In doing this, buses and carpools receive a travel time advantage and a more reliable trip, thus encouraging transit use and reducing the need for more pavement to meet ever growing corridor demand.

Added benefits of this designated lane treatment are its ability to flexibly serve a significant transit market without the need for a fixed guideway investment. Air quality is preserved with a commensurate reduction in emissions that would otherwise be created by more cars. In helping to sustain and enhance an existing and growing transit market, the overall economy of New York and New Jersey is sustained with this lane management strategy.