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9 From an operational protocol standpoint, the IBL system There are two types of stop modifications associated with is to be activated only when the flow of the general traffic is the implementation of TSP: (1) stop relocation and/or con- operating below a speed that inhibits bus transit speeds. solidation along a corridor, and (2) moving specific stops to When that threshold is reached--through the technologies enhance another priority treatment. of computers and sensors that can provide knowledge of real-time traffic conditions--longitudinal flashing lights embedded in the roadway lane divider are activated to warn Corridor Stop Relocation and/or Consolidation general-purpose drivers that they cannot enter that lane and a This strategy is applied when a new BRT or express bus ser- bus is approaching. Vehicles already in the lane are allowed vice is implemented along a corridor. By having such services to continue. This leaves a moving gap or moving time win- make fewer stops, travel time savings and improved on-time dow for the bus to travel through. For this treatment to be performance for the service as a whole can be achieved irre- effective, driver education and enforcement is paramount. spective of any added preferential treatments being applied. Where an average stop spacing might be two to three blocks When the traffic conditions are not expected to cause delays for local bus service (8001,200 ft), for new BRT service min- to the bus movement, the IBL should not be activated. imum stop spacing is typically 0.5 to 1 mile. The 0.5 mile stop spacing is typically associated with 0.25 to 0.5 mile Figure 8 shows the signalization/signage for an inter- being an acceptable walking distance to such a premium bus mittent lane demonstration project in Lisbon, Portugal. There service. For express bus service, stop spacing is even greater, currently is no application of intermittent lanes in North with typically just a couple of intermediate stops between the America. outer stop of a line (in many cases associated with a park-n- ride facility) and downtown. It should be noted, however, STOP MODIFICATIONS that there are many cases where the existing local bus service alone has too many stops, and there are benefits of eliminat- Modifications to stop placement can create some travel time ing or moving stops to go from a one- to two-block stop pat- savings for transit operations along urban areas or allow tern to a three- to four-block stop pattern and provide some another preferential treatment (such as signal priority) to be travel time savings and adequate accessibility to adjoining more effectively applied. Given the relative inexpense of neighborhoods. moving bus stops versus full LRT stations, modifications to stop placement are typically focused on bus operations, par- In downtown areas, the concept of skip-stop operation ticularly new BRT or express bus services. is sometimes applied for bus operations. This concept (a) (b) FIGURE 8 Intermittent lane application--Lisbon, Portugal: (a) Vertical signalization--Variable message sign, (b) Horizontal signalization--Pavement light-emitting diodes [Source: "The Intermittent Bus Lane System: Demonstration in Lisbon" (7 )].
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10 FIGURE 9 Bus stop spacing alternatives (Source: PB Americas, Inc.). involves having bus routes stop at every second or third Figure 9 illustrates the relationship between local, limited stop, thereby reducing the dwell time for buses at a stop and BRT, and express bus stop spacing patterns in a transit cor- and facilitating passenger boarding. This is not unlike ridor. Figure 10 shows the existing skip-stop bus operation on the concept of having dedicated bus bays at a bus terminal. 17th Street in downtown Denver. Critical to the success of skip-stop operations is the avail- ability of a passing lane that allows buses to pass one This strategy is applied at a specific location, typically an another. intersection, where moving a stop (from near side to far side, FIGURE 10 Example of bus skip-stop pattern--17th Street, Denver, Colorado, Moving Specific Stops (Source: Denver Regional Transportation District).