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identification (AVI) tag, transponder, or other electronic device to use an HOV lane for free. Some such programs focus on encouraging use of environmentally friendly vehicles. Value pricing pro- grams, also called priority pricing or HOT lanes depending on the application, may under agency- specified conditions allow higher occupancy vehicles to use a toll facility at a discount or for free, or allow single occupancy vehicles (SOVs) or lower occupancy vehicles (LOVs) to use an HOV facility for a charge. Arterial Street HOV Facilities. A few areas operate priority lanes on arterial streets open to the full HOV mix of buses, vanpools, and carpools. Examples range from lanes on streets with unlimited access to lanes on expressways with limited access control in combination with at-grade intersections. Arterial Street Bus-Only Facilities. The variety of arterial street bus-only facility designs includes bus streets, transit malls, and bus lanes. All types are typically applied in downtown situations. Exceptions include some transit malls located in major suburban activity centers and a few instances of longer distance urban bus lane applications. Bus streets or transit malls are entire streets reserved primarily for public transit vehicles along with pedestrians and usually bicycles. Some allow taxis in addition to buses, most provide for off-hour deliveries, and all provide emer- gency vehicle access. Bus-only lanes involve reserving an existing or new lane for use by buses or buses and taxis during peak periods or all day. Usually this is the curb lane, although the second lane from the curb or median lanes are used in a few areas. Bus lanes may operate in the same direc- tion as the normal flow of traffic, or less commonly, contraflow. While most bus lanes have straightforward paint striping and signing, safety experience has led to identifying contraflow bus lanes with more extensive signage, sometimes with special curbs to achieve physical separation from the other traffic lanes. Managed Lanes. The term "managed lanes" has different meanings to different groups (Collier and Goodin, 2004). It applies primarily to freeways and other limited access highways. The Project Monitoring Committee for a Texas Transportation Institute and Texas Southern University research effort accomplished in cooperation with the Texas Department of Transportation and the Federal Highway Administration (FHWA) has adopted the following definition: "A managed lane facility is one that increases freeway efficiency by packaging various operational and design actions. Lane management operations may be adjusted at any time to better match regional goals." Strategies that may be employed to facilitate traffic flow on managed lanes include restricting access to certain types of vehicles, such as buses, carpools, trucks, or toll-paying vehicles; varying restrictions by time of day; and value pricing. Value pricing approaches may include charging at varying rates according to time of day (Texas Transportation Institute and Texas Southern University, 2005), travel conditions, and/or vehicle type. Managed Lanes are not an HOV classifi- cation specifically addressed within the "Response by Type of HOV Application" section of this chapter. The concept is introduced, however, at the conclusion of the "Related Information and Impacts" section under "Modification and Expansion of HOV Functions." ANALYTICAL CONSIDERATIONS Results of before and after evaluations of actual projects, counts and surveys of new and mature operations, feasibility studies comparing potential alternatives, and travel demand model estimates 2-4