Another method that is being increasingly used to relieve congestion on urban freeways is the establishment of high-occupancy vehicle (HOV) lanes. Although the first instances of use in California in the early 1970s met with much public resistance, the idea was revisited and accepted more readily during the mid-1980s and continues to grow in acceptance in highly congested urban traffic areas (Ref. 9). The concept is to provide a separate lane or lanes for high-occupancy vehicles such as buses, carpools, vanpools, and other ride-sharing modes of transportation. This, in turn, provides a positive incentive for the general public to seek out ride-sharing transportation modes, both public and private. The overall goal is to move more people in fewer vehicles.
2.13.1 Planning Considerations
The following transportation system goals can be achieved by proper development and use of HOV lanes (Ref. 3):
• To maximize the person-moving capacity of roadway facilities by providing improved level of service for high-occupancy vehicles, both public and private
• To conserve fuel and to minimize consumption of other resources needed for transportation
• To improve air quality
• To increase overall accessibility while reducing vehicular congestion
Designing and implementing HOV lanes should be limited to those cases where extreme congestion occurs on a regular basis. They should be used in conjunction with other programs that will promote the use of ride-sharing modes, such as park- and-ride lots, park-and-pool lots, and information services to facilitate bus and ride — share needs.
The following guidelines should be used to determine when an HOV lane should be implemented:
• Compatibility with other plans
HOV lanes should be part of an overall transportation plan.
Community support should be obtained for developing HOV lanes.
Intense, recurring congestion should be occurring on the freeway general-purpose lanes.
Peak-period traffic per lane should be approaching capacity (1700 to 2000 vehicles per hour).
During peak periods, average speeds on the freeway main lanes during nonincident conditions should be less than 30 mi/h (48 km/h) over a distance of about 5 mi (8 km) or more.
Compared with using the freeway general-purpose lanes, the HOV lanes should offer a travel time savings of at least 5 to 7 min during the peak hour.
• Coordination with travel patterns that encourage ridesharing
Significant volume of peak-period trips (e. g., more than 6000 home-based work trips during the peak hour) on the freeway should be destined to major activity centers or employment areas in or along the freeway corridor.
At least 65 to 75 percent of peak-period freeway trips to major activity centers should be 5 mi (8 km) or more in length.
Resulting ride-share demand should be sufficient to generate HOV volumes that are high enough to make the facility appear to be adequately utilized; volumes may vary by type and location of facility.
• A design that allows for safe, efficient, and enforceable operation
