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CHAPTER ONE
INTRODUCTION
BACKGROUND A potential application for BBS is to support "station stop-
ping" bus operation along highways with center median HOV
In many urban areas, traffic congestion regularly delays bus lanes. Station stopping buses follow bus routes that make
services and adversely affects schedule reliability. Many com- many passenger stops at interchanges along a corridor. This
munities have adopted measures such as bus priority lanes, bus mode of bus operation is similar to the operation of most light
signal priorities, or improved fare collection policies to im- rail systems, which make station stops approximately every
prove speed and reliability. Some communities have adopted mile along major travel corridors. Use of median HOV lanes
policies and regulations that permit buses to use arterial or for station stopping bus routes tends to be very challenging,
freeway shoulders to bypass congestion either as interim or particularly where freeway buses stop at each interchange or
long-term treatments. At the outset of the study, Maryland, every other interchange. These short station distances make
Minnesota, Virginia, Washington, British Columbia, and bus weaving to and from the median HOV lanes problematic.
Ontario were among the jurisdictions that had implemented or Significant time is lost, disruption is increased to the HOV
were considering implementing bus use of shoulder programs. traffic flow and intervening travel lanes, and safety concerns
However, because little information was available about travel arise with these short distance bus weaves. To contend with
time, reliability, patronage benefits, and safety impacts result- these issues a number of agencies have constructed expensive
ing from allowed use of shoulders, many jurisdictions have direct access ramps to the HOV lanes.
been reluctant to embrace bus use of shoulders.
Another potential application is that of a "queue jumper,"
Buses bypassing traffic congestion on shoulder lanes can allowing buses to bypass congestion at a traffic bottleneck.
help make bus use more attractive. Travel time reliability and These applications tend to be short and to involve no or only
travel time competitiveness are both key factors that attract minimum ramp weaving conflicts. The short lengths of these
"choice riders" to bus transportation. These are basic advan- queue jumper applications often require minimal shoulder
tages that rail and bus systems operating on exclusive rights- upgrade cost and can provide significant travel time and
of-way provide, and they help to explain why these systems reliability benefits.
are more successful than conventional bus services operating
in mixed-use traffic. The marketing and psychological mes- Permitting buses to use shoulder lanes to bypass conges-
sage of buses passing motorists stuck in traffic congestion tion, however, raises potential conflicts with the intended
tends to be powerful. In essence, bus bypass shoulder (BBS) purpose of shoulder facilities. Highway shoulders generally
use operations reduce passenger travel times and help improve provide space for disabled vehicles, emergency services, and
travel time reliability. enforcement efforts. They also provide a safety buffer and re-
covery area between the general travel lanes and lateral
BBS is used by a number of agencies to describe bus use obstructions. In snow climate areas they can be used for tem-
of shoulders. This acronym was adopted for use in this report porary snow removal. They are not intended to be used for
and is suggested for use in subsequent technical reports. debris storage, but sometimes serve this function. Allowing
buses to use the shoulder lanes therefore compromises these
Along many congested freeway corridors, widening to basic shoulder functions. The extent of these compromises
provide a bus-only lane is not a viable option because of right- varies by corridor and is difficult to quantify.
of-way constraints, environmental concerns, and/or high cost.
In these restricted corridors the use of outside shoulders by Another important issue is that most shoulders are not con-
buses to bypass congestion provides a means to increase the structed to the full structural requirement as general traffic
person carrying capacity of the corridor without expanding lanes and most are narrower than conventional traffic lanes.
rights-of-way. The shoulder use concept is less disruptive Design requirements for shoulder facilities vary by state and
than widening projects to implement, is relatively low cost, have included upgrades over the years. Older highways tend
and can be put into practice relatively quickly. Visually, the to have the narrowest and least accommodating design
BBS concept is less obtrusive than large highway ramps con- standards. AASHTO's A Policy on Geometric Designs of
structed to allow buses direct access into center median high- Highways and Streets (1) currently recommends a minimum
occupancy vehicle (HOV) lanes. 10-ft-wide right shoulder for highways with modest volumes
