HOV Priority
Strategies to Improve Transit and Ridesharing Speed and Convenience
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TDM
Encyclopedia
Victoria Transport Policy Institute
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Updated
March 7, 2007
This chapter describes High Occupant Vehicle (HOV) priority strategies.
HOV Priority refers to strategies that give priority to High Occupant Vehicles (also called Rideshare Vehicles), including transit buses, vanpools and carpools. Priority bus service is sometimes called Bus Rapid Transit. HOV Priority is a major component of many regional TDM programs. Two, three or four occupants (indicated as 2+, 3+ or 4+) may be required to be considered an HOV, depending on circumstances. This is opposed to Single Occupant Vehicles (SOVs).
HOV Priority includes:
· HOV highway and arterial lanes. These are sometimes reversible (or “counter flow” lanes), which means that they provide traffic capacity in the peak direction. Lanes open only to buses are called busways. These are a type of managed lanes (WSDOT, 2001; Obenberger, 2004; Goodin, 2005).
· High Occupancy Toll (HOT) lanes. These are HOV lanes that also allow low occupancy vehicles if they pay a toll, as described in Road Pricing.
· Busways, that is, special lanes dedicated to transit buses, often incorporating other features to insure high quality transit service.
· Queue-jumping lanes (other vehicles must wait in line to enter a highway or intersection, but HOVs enter directly).
· Intersection controls that give priority to HOVs. For example, a traffic light might be set to stay green for several extra seconds if that allows a bus to avoid stopping.
· Streetscape changes to favor High Occupant Vehicles, such as improved bus stops and bus pullouts.
· Preferred parking spaces or parking fee discounts provided to rideshare vehicles (Parking Management).
· Special benefits to HOV riders, often included in Commute Trip Reduction programs.
Bus Rapid Transit (BRT) is a term used for a set of Transit Improvements that include grade-separated right-of-way and other transit priority measures, comfortable stations, high-quality vehicles (high capacity, easy to board, quiet, clean and comfortable to ride), frequent service, convenient user information, efficient pre-paid fare collection, and efficient operations.
HOV Priority provides travel time savings, operating cost savings and increased travel reliability. HOV lanes typically provide time savings from 0.5-minute per mile on arterial streets up to 1.6-minutes per mile on congested freeways. Queue-jumper HOV facilities can provide savings up to 20 minutes (Turnbull, Levinson and Pratt (2006). Many travelers place a high value on these time savings, particularly if unpredictable delays are reduced.
|
Under,
Over or Through Grade
separation means that high occupancy vehicles have separate right-of-way, so
they are not delayed by traffic congestion. This can be accomplished by
providing separate rights-of-way, giving transit vehicles priority at
signaled intersections, creating grade-separated intersections, and locating
lines underground (subways) or above roadways (elevated lines and SkyTrain).
All can be effective, although from a users perspective underground tends to
be least pleasant, since users must descend underground to stations and have
no views while traveling. Fully grade-separated underground and elevated
systems are generally faster, but surface-level systems eliminate the need to
descend/ascend to stations, which can save two or three minutes per trip,
making them relatively attractive, particularly for shorter trips. Many
transit systems use a combination of these features to increase transit
speeds. |
HOV Priority effectiveness depends on maintaining significant travel advantage for efficient modes. There is often pressure to compromise this advantage to achieve other objectives. For example, special interest groups often lobby to reduce HOV requirements, such as from 3+ to 2+, and to allow single occupant vehicles such as motorcycles, hybrid cars and taxis; and transportation agencies are sometimes under financial pressure to maximize the number of single-occupant vehicles allowed if they pay on High Occupant Toll lanes. Ideally, HOV lanes should be uncongested, maintaining Level Of Service (LOS) A or B, which means less than about 1,000 vehicles per hour on a grade-separated highway and half that on a surface street (Congestion). Buses typically impose about two Passenger Car Equivalents (PCEs) and vans about 1.2. Thus, if there are 100 buses during a peak period, causing 200 total PCEs, the available capacity totals about 800 PCEs on grade-separated highways and just 300 PCEs on surface streets. In several cases these limits have been exceeded, spoiling the HOV advantage and contradicting strategic transport planning objectives.
The value of HOV Priority depends on the criteria and assumptions used in evaluation (Wellander and Leotta, 2001). HOV priority measures can be justified as a more efficient and equitable allocation of road space (travelers who share a vehicle and therefore impose less congestion on other road users, are rewarded by bearing less congestion delay), an efficient use of road capacity (they can carry more people than a general use lane), and as an incentive to shift to more efficient modes. HOV lanes usually carry fewer vehicles than other lanes but they often carry more people.
Evaluation also depends on whether the HOV facility uses an existing highway lane or is new capacity, and whether the alternative to HOV lanes would be no additional capacity, additional general use lane, or an additional transit lane. Some critics oppose HOV lanes on the grounds that they increase total road capacity and encourage longer-distance commuting (Leman, Schiller, Pauly, 1996; Szoboszlay, 1999), while others oppose them on the grounds that they are underutilized (Orski, 2001). HOV lanes often take years to reach their full potential, since they affect long-term decisions such as where consumers live or choose to work.
Below are criteria used to evaluate HOV facilities in
·
Total Person Throughput. This is a measure of how
many people move past a point in a given period in time. Traditionally
transportation agencies measure only the number of vehicles, but on HOV lanes
they measure the number of vehicles, number of people per vehicle, and the
number of people using transit. Increased person throughput and higher average
vehicle occupancy are goals.
·
Travel Times. Transportation agencies
measure travel time to determine how long it takes HOVs, SOVs and freight
vehicles to travel on roads with HOV lanes. No net increase in travel times
during the afternoon rush hour is a goal.
·
Safety. Agencies measure the
accident and incident rates on sections of highway before and after HOV lanes
are established. No increase in incident and crash rates is a goal.
·
Enforcement. This is a qualitative
measure of how enforceable a HOV lane is. Agencies will track the number of
tickets issued, the HOV lane violation rate and observations of police
enforcing the lane. Minimal violation rate, and maximum perception that users
obey HOV rules is a goal.
·
Beginning and Ending
Transitions. The
beginning and ending of an HOV lane can create weaving movements or other
traffic flow problems. Agencies will monitor the traffic operations to evaluate
how HOV lanes affect traffic flow.
·
Traffic Diversion. There is a concern that excessive
delays in general purpose lanes may cause traffic to divert to parallel routes.
Traffic counts will be taken before and after HOV lanes are established to
determine if significant traffic is diverted. The goal is to minimize traffic
diversion.
·
·
Transit Ridership. Agencies will track how
many people ride transit during peak periods when the HOV lane is in service.
·
Increase in Transit Service.
Agencies
will measure the increase in transit service and compare it to the increase in
transit ridership. This would help understand the increase in transit ridership
due to the HOV project compared to normal increases in ridership that result
from an increase in transit service (without an HOV lane).
·
Number of People Per
Vehicle. Agencies
observe traffic to determine the number of people per vehicle during peak
periods.
·
Park & Ride Use, Van
Pools & Employer Programs. Agencies will track the use of the Park & Ride
and vanpools.
·
Public Perception. Agencies survey commuters
and compare responses before and after HOV lanes are established.
HOV facilities can be implemented by adding new road capacity designated for HOVs. Sometimes, existing lanes are converted to HOV use (called “take a lane”). HOV lanes can be separated from regular traffic using signs, markings, painted buffer or physical barriers. HOV lanes can be 24 hour or designated for peak hours only, and some use reversible lanes. HOV programs are most successful as part of an integrated regional transportation strategy that includes other improvements and incentives for transit and rideshare use.
(Turnbull, Levinson and Pratt, 2006) suggests that HOV highway lanes are most effective at reducing automobile use on congested highways to large employment centers in large urban areas with 25 or more buses per hour during peak periods, where transit provides time savings of at least 5 to 10 minutes per trip. Turnbull (2001) provides guidelines for implementing HOV facilities which suggest that they are most effective in major urban areas with large employment centers, heavy congestion and supportive TDM policies.
HOV Priority improves the performance of transit and ridesharing (a direct benefit to users), and encourages shifts from SOV to HOV travel modes (which benefits all road traffic). Travel time savings and mode shift effects depend on circumstances, including the degree of congestion and the facility design. Turnbull, Levinson and Pratt (2006) provide detailed discussion of the travel effects of various types of HOV facilities.
Comsis (1993) and Turnbull, Levinson and Pratt (2006) find
that HOV facilities can reduce vehicle trips on a particular roadway by 4-30%.
Adding HOV lanes can be considered to increase total automobile travel compared with no additional road capacity, and HOV priority can sometimes encourage longer-distance trips (and therefore sprawl), and may attract some travelers from other alternative modes, such telecommuting and cycling.
The travel impact of HOT lanes depends on the price structure used. If the price is too low, the facility will experience congestion, reducing the performance for both single-occupant vehicle users and HOV users, resulting in reduced transit and ridesharing. It is therefore important for the sake of overall transportation system efficiency that HOT facilities be managed to favor HOV performance.
Table 1 Travel Impact Summary
|
Travel
Impact |
Rating |
Comments |
|
Reduces total traffic. |
2 |
Encourages HOV use during
peak periods. |
|
Reduces peak period
traffic. |
3 |
|
|
Shifts peak to off-peak
periods. |
0 |
|
|
Shifts automobile travel to
alternative modes. |
3 |
|
|
Improves access, reduces
the need for travel. |
0 |
|
|
Increased ridesharing. |
3 |
|
|
Increased public transit. |
3 |
|
|
Increased cycling. |
0 |
|
|
Increased walking. |
0 |
|
|
Increased Telework. |
0 |
|
|
Reduced freight traffic. |
0 |
|
Rating from 3 (very
beneficial) to –3 (very harmful). A 0 indicates no impact or mixed impacts.
Benefits include increased travel speeds and reliability for HOV passengers. This increases Transportation Options by allowing travelers to choose between driving alone in congestion or bypassing congestion in an HOV. HOT facilities add a third option: SOV drivers can avoid congestion by paying a toll. This allows individual consumers to choose which option best suits their needs for each trip.
HOV Priority measures can increase transit service efficiency by increased ridership per vehicle-hour and reduced fuel consumption per vehicle-mile. For example, an HOV Priority system that increases average travel speeds on a particular transit route from 25 to 20 minutes increases maximum carrying capacity and revenue per bus-hour by 20%.
To the degree that HOV Priority causes urban peak travelers to shift from driving to alternative modes it can be an effective Congestion Reduction strategy, and help achieve other TDM objectives. Because HOV facilities tend to have their greatest impact on highly congested urban corridors, they can provide significant benefits in terms of road and parking facility cost savings, transit system operating cost savings, congestion and pollution reductions, and consumer benefits (Transit Evaluation).
HOV Priority can reduce pollution emissions by smoothing
vehicle flow and attracting travelers from automobiles. Table 2 summarizes the
estimated pollution emission reductions from particular bus priority measures
in
Table 2 Bus
Priority Measures in
|
Measure |
Proportion of Buses Affected |
Exhaust Emission Reduction Per Bus
Affected |
|
Peak period bus lane |
5% |
20% |
|
Contra-flow lane, all day |
2% |
35% |
|
Signal pre-emption |
20% |
12% |
|
Segregated bus street |
2% |
60% |
|
Priority turns |
5% |
7% |
Costs include project construction, management and
enforcement. Some critics argue that HOV lanes encourage urban sprawl and
contribute to poor air quality (Leman, Schiller and Pauly, 1994), while others
argue that they are an inefficient use of road capacity (Orski, 2001). A study
by Varaiya (2005) found that 2-Plus carpool lanes in
Table 3 Benefit Summary
|
Objective |
Rating |
Comments |
|
Congestion Reduction |
3 |
HOVs avoid congestion, encourages mode shifting. |
|
Road & Parking Savings |
0 |
Involves project costs, but
usually cheaper for roads and parking than accommodating the same number of
trips by SOV. |
|
Consumer Savings |
2 |
Provides consumer time
savings. |
|
Transport Choice |
3 |
Allows consumers to avoid
congestion by using HOV modes. |
|
Road Safety |
0 |
Mixed. Safety benefits from
reduced driving may be offset by operational hazards. |
|
Environmental Protection |
2 |
Encourages mode shifting. |
|
Efficient Land Use |
-1 |
May encourage
longer-distance commutes and sprawl. |
|
Community Livability |
1 |
Reduces automobile trips. |
Rating from 3 (very beneficial) to –3 (very harmful). A 0 indicates no impact or mixed impacts.
Some people consider HOV Priority unfair because it favors one group (HOV passenger) over other road users. Others consider HOV priority a fairer allocation of road space by giving travelers who use less space, and therefore contribute less to traffic congestion, priority over those who use more space. Some critics argue that HOV lanes do not meet the needs of people who cannot use transit (e.g., parents who drive alone to pick up their children are cited as examples), but others argue that many people who drive alone could use HOVs, but choose not to, and that SOV users benefit from reduced congestion if HOV Priority causes mode shifting.
HOV facilities benefit transit and rideshare passengers, which includes a proportionally large share of lower income and transportation disadvantaged people, and is therefore progressive with respect to income and need. HOT lanes have been criticized as elitist because wealthy motorists are able to avoid congestion experienced by lower-income motorists (Pricing Evaluation). HOV Priority can help achieve Basic Mobility by favoring basic modes (transit and ridesharing) over automobile travel.
Table 4 Equity Summary
|
Impacts |
Rating |
Comments |
|
Treats everybody equally. |
0 |
Mixed. Depends on
assumptions and circumstances. |
|
Individuals bear the costs
they impose. |
3 |
Reduces congestion
externalities. |
|
Progressive with respect to
income. |
3 |
Lower-income people tend to
rely on HOVs. |
|
Benefits transportation
disadvantaged. |
3 |
Benefits HOV users, which
includes transportation disadvantaged people. |
|
Improves basic mobility. |
3 |
Improves basic access. |
Rating from 3 (very
beneficial) to –3 (very harmful). A 0 indicates no impact or mixed impacts.
HOV facilities are most appropriate on congested highways where it is technically feasible to convert or add lanes, where HOV use could increase, and which would result in significant time savings to users. Transit priority traffic controls can be implemented on surface streets in any urban area. Resort communities can give traffic and parking priority to buses. Developers and businesses can provide priority parking for HOVs, and transit priority in loading areas.
Table 5 Application Summary
|
Geographic |
Rating |
Organization |
Rating |
|
Large urban region. |
3 |
Federal government. |
3 |
|
High-density, urban. |
3 |
State/provincial
government. |
3 |
|
Medium-density,
urban/suburban. |
2 |
Regional government. |
3 |
|
Town. |
1 |
Municipal/local government. |
3 |
|
Low-density, rural. |
0 |
Business Associations/TMA. |
2 |
|
Commercial center. |
3 |
Individual business. |
1 |
|
Residential neighborhood. |
1 |
Developer. |
1 |
|
Resort/recreation area. |
3 |
Neighborhood association. |
1 |
|
|
|
Campus. |
3 |
Ratings range from 0 (not
appropriate) to 3 (very appropriate).
Incentive to Use Alternative Modes
HOV programs support and are supported by other Transit and Rideshare encouragement efforts, including Commute Trip Reduction, Parking Management, Park-and-Ride, and Marketing efforts. HOV Priority is a way to Prioritize Transportation and Reallocate Road Space.
HOV facilities are implemented through partnerships between provincial/state departments of transportation, local and regional transportation and planning authorities, ridematching organizations, Transportation Management Associations, and highway patrol and enforcement bodies.
HOV facilities are often expensive to construct, may cause traffic operation and enforcement problems, and may be controversial. SOV drivers may oppose HOV on the grounds that they are unfair and ineffective, in preference to general-purpose lanes. Others may oppose HOV facilities on the grounds that they increase total road capacity, leading to increased total vehicle traffic and urban sprawl.
Turnbull, Levinson and Pratt (2006) and Turnbull (2001) provide guidelines for effective HOV facilities. These include:
· More than one million people in the metropolitan region.
· High levels of traffic congestion in the corridor.
· Access to an employment center with 100,000 or more workers.
· Well designed facilities.
· 25 or more buses during peak periods.
· Supportive TDM programs and policies with ongoing marketing.
· Visible enforcement.
· Cooperation among responsible transportation agencies.
|
A
drunk was hanging out on a street corner. Another drunk walks by holding a
large bag. The first drunk asked, “Hey, what have you got in that bag there? “Wine.
Bottles of very valuable wine,” was the reply. “How
many bottles do you have in that bag then?” the first drunk asked. “I’m
not telling,” he replied. “Will
you share some with me?” asked the first drunk. “I’ll
tell you what,” replies the second drunk, “If you guess how many bottles I
have in this bag – I’ll give both of them to you!” |
The Virginia
Department of Transportation (VDOT) launched HOVcalculator.com, a Web site that
allows
HOVcalculator.com
users enter the typical time of their commutes as well the longest time their
commutes may take. They also enter the names of landmarks closest to their home
and office and the calculator tells them how many minutes they would save by
using the HOV lanes. The calculator also offers information about the nearest
park-and-ride lots and their features-such as bus service or vanpools. Data for
HOVcalculator.com was gathered under typical morning rush-hour conditions from
travel-time studies conducted by the Council of Governments and VDOT.
Comsis (1993), and Turnbull,
Levinson and Pratt (2006) describe numerous successful HOV facilities in