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This chapter covers the totality of HOV facilities, inclusive of supportive features, but without
examining supportive features in detail. Express bus operations and park-and-ride and park-and-
pool facilities are supportive features that enhance the operation of many HOV facilities. These
are the subjects of Chapter 4, "Busways, BRT and Express Bus," and Chapter 3, "Park-and-
Ride/Pool."
OBJECTIVES OF HOV FACILITIES
The primary and interrelated goals of HOV facilities are to provide buses, carpools, and vanpools
with travel time savings and more predictable travel times, and to thereby induce individuals
to choose a higher occupancy mode over driving alone. Supporting services, facilities, and
incentives are often used as further encouragement for significant numbers of individuals
to change their commuting to a more cost-effective, higher-occupancy travel alternative. The
person movement capacity of the roadway is increased when more people are carried in fewer
vehicles.
HOV facilities are usually found in heavily congested corridors and areas, frequently with heavy
bus volumes. Typically the physical and financial feasibility of expanding the roadway is limited.
HOV projects have largely focused on meeting one or more of the following three objectives
(Turnbull, 1992a):
· Increase the Average Number of Persons per Vehicle. Travel time savings and travel time reli-
ability offered by HOV facilities offer incentives or reduce disincentives for individuals to
change from driving alone to using a bus, vanpool, or carpool. HOV projects focus on moving
people, rather than vehicles, by increasing the average number of people per vehicle on the
roadway or travel corridor.
· Preserve the Person Movement Capacity of the Roadway. An HOV lane, which may move
two to five times as many persons as a general-purpose (GP) lane, has the potential to double
the capacity of a roadway to move people. The vehicle occupancy requirements can be raised
if a lane becomes too congested, to help ensure that travel time savings and travel time
reliability are maintained.
· Enhance Bus Transit Operations. Bus travel times, schedule adherence, and vehicle and labor
productivity may improve as a result of an HOV facility, helping attract new bus riders and
enhancing transit cost effectiveness. Many transit agencies have expanded or initiated express
bus services in conjunction with HOV facilities, to attain a flexible, easily staged, and relatively
low cost form of high capacity express transit.
TYPES OF HOV FACILITIES AND TREATMENTS
The various types of HOV facilities, treatments, and programs are characterized here to establish
a discussion framework. Unless otherwise noted, examples are provided later in this chapter in the
corresponding "Response by Type of Strategy" sections and tables.
Busways or HOV Lanes in Separate Rights-of-Way. This approach to providing HOV
priority uses roadways or lanes developed on alignments mostly separate from the highway
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system. Existing projects are two lane, two direction facilities for buses and special permit vehicles
only, like the busways of Pittsburgh and Ottawa, Canada. This type of facility is not addressed in
this chapter. Examples and information related to traveler response to transit services operated on
such facilities are found in Chapter 4, "Busways, BRT and Express Bus."
Exclusive Freeway HOV Lanes. Exclusive freeway HOV lanes include both two-directional HOV
lanes and reversible HOV lanes. Both types are constructed within a freeway right-of-way, are
physically separated from the GP (mixed traffic) freeway lanes--typically by barriers or wide
buffers--and often have direct access ramps. Exclusive two-directional facilities serve traffic flow-
ing in both directions at the same time. Reversible HOV facilities operate inbound toward the cen-
tral business district (CBD) or other major activity center in the morning and outbound in the
afternoon.
Concurrent Flow Freeway HOV Lanes. These most common of freeway HOV lanes operate in the
same direction of travel as the GP traffic lanes and are separated only by normal paint striping or
a 2 to 4 foot painted buffer. They are designated for exclusive use by HOVs for all or a portion of
the day. Concurrent flow lanes are usually located on the inside lane or shoulder, next to the free-
way median, but a few outside HOV lanes are utilized.
Contraflow Freeway HOV Lanes. The contraflow lane approach takes an underutilized freeway
lane from the off-peak direction of travel, typically the innermost lane, for exclusive use by HOVs
traveling in the peak direction. The lane is separated from the remaining off-peak direction GP
travel lanes by some type of changeable treatment, such as removable plastic pylons inserted into
corresponding holes or moveable concrete barriers. Contraflow lanes are typically operated dur-
ing the peak period in the direction of peak flow, reverting back to normal use in other periods.
Often they are limited to use by buses only.
Ramp Meter Bypasses and HOV Access Treatments. This type of strategy can give HOVs prior-
ity at metered freeway entrance ramps by providing either a separate lane located adjacent to the
metered GP lane or a separate HOV entrance ramp. Either way, they allow HOVs to move around
the traffic queue at the meter or otherwise directly enter the freeway. These techniques may be
used in combination with a freeway HOV lane or as a stand alone measure. Direct access ramps
from adjacent roadways, park-and-ride lots, and transit stations are also employed in some areas
to provide buses, and sometimes vanpools and carpools, with extra travel time savings and trip
time reliability.
Changes in Occupancy Requirements and Operating Hours. Changing vehicle occupancy
requirements is an HOV lane demand management strategy that involves modifying the
HOV lane use eligibility requirements. The occupancy requirement may be lowered to encourage
use, such as from three persons per vehicle (3) to two persons (2), or may be increased to
mitigate HOV lane congestion and preserve HOV travel time advantages. Changes in hours of
operation alter the balance of time allocated to HOV priority--usually peak-travel periods at a
minimum--as compared to time when the facility reverts to GP lane status, giving all vehicles
equal access.
HOV Facility Exempt Vehicle and Value Pricing Programs. These various programs have
been tested in one or more areas, some on a strictly experimental basis and a number moving
into continuing status. Most are designed primarily to manage demand on existing or new
HOV lanes to attain higher lane utilization than might otherwise be possible. Exempt vehicle
programs allow qualified vehicles with a valid sticker, license plate, or automatic vehicle
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