Abus bulb, also called abus boarder,bus border,bumpout,bus cape,[1] or akerb outstand is an arrangement by which asidewalk or pavement is extended outwards for abus stop; typically the bus bulb replaces roadway that would otherwise be part of aparking lane. With bus bulbs or boarders, abus can stay in itstraffic lane to discharge and pick up passengers, instead of having to pull over to the curb.
The term bus bulb is prevalent inNorth American usage, whilst bus boarder or bus border is used elsewhere.[2][3][4]
A bus bulb or boarder can be considered as a specific form ofcurb extension, although that term is more normally used to describe a sidewalk extension for the purposes oftraffic calming or othertraffic management purposes.
Benefits include preventing buses from being delayed by having to pull back into traffic, reducing risk oftraffic collisions, reducing pedestrian exposure incrosswalks (if provided at the same location), reducing sidewalk congestion, providing space for bus patron amenities includingbus shelters, andtraffic calming. The protrusion also facilitates easier full length alignment of a bus entrance with a raised kerb stop, especially to allow level boarding in the case oflow-floor buses.[3]
Bus bulbs also retain more parking when compared to a bus stop located in a parking lane, as a bus stop so located requires run-in and run-out tapers. Together these tapers may take up as much space as the actual stop, requiring parking to be prohibited over a longer length of road than with a bulb, where cars can park immediately on either side of the bus stop itself.[3]
Standard bus bulbs can create safety hazards for cyclists. In a standard bus bulb design, the narrowing of the road can create danger for cyclists by making them merge back into traffic.[3][5]
To resolve this issue, multiple designs exist to integratebike lanes into bus bulbs. TheNational Association of City Transportation Officials recommends two types of modified bus bulbs that integrate with bike lanes: "boarding islands" and "shared boarding areas." The "boarding island" design routes the bike lane behind the bus bulb, and the "shared boarding area" design uses a ramp to route the bike lane through the bus bulb. Both designs require cyclists to yield to passengers boarding and disembarking at the stop.[6][7]
Where more than one lane exists in one direction, modelling has shown that there is no additional delay overall for following drivers, since the buses have shorterdwell times (there is less time spent pulling back into traffic) and since following vehicles may use the second lane for passing.[2]
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Sometram andstreetcar systems use similar bulbs, such as theBrusselstram network,[citation needed] theHongkong Tramways, theMelbourne tram network[8] and theToronto streetcar system.
The latter, which operates mostly on traditionalstreetcar tracks in mixed traffic with cars, and has frequent request stops similar to bus routes, is introducing bulbs at some high-traffic stops and transfer points that have been recently renovated, notably onRoncesvalles Avenue. The first bulbs (calledbumpouts locally) along Roncesvalles Avenue also accommodate cyclists, as the bike lane running parallel to the streetcar tracks would gently rise up from the road level to run on top of the bumpout. When the streetcar is boarding, cyclists have to stop behind the yellow line to allow riders on and off.[9] There are three expected goals for these bulbs:
Streetcar bulbs may also be beneficial at higher-capacity stops along other streetcar routes, and may be rolled out in conjunction withlonger streetcars on the route. These bulbs are also featured in the westbound of Johnston Road, as well as southbound Percival Street and westbound Catchick Street in Victoria City, Hong Kong Island, on the Hongkong Tramways.
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