This report describes a framework for determining when bus lanes are warranted. Bus lanes increase urban transport system efficiency and equity by favoring higher value trips and more space-efficient modes over lower-value trips and space-intensive modes. Bus lanes can carry more passengers than general traffic lanes, and so increase total capacity (people per traffic lane), increase transit system operating efficiency, directly benefit bus passengers, cause travelers to shift from automobile to transit which reduces various transportation problems, and support more transit-oriented development. This paper examines how these impacts are considered in conventional planning, describes examples of bus lane planning and evaluation, and discusses ways to optimize their implementation. This analysis suggests that bus lanes are generally warranted where, after all economically justified pro-transit policies are implemented, they would attract more than 800 peak-hour passengers (about 20 buses) on surface streets or 1,800 peak-hour passengers (about 40 buses) on grade-separated highways, since they carry more passengers than a general traffic lane, and so save total travel time. Bus lanes are often justified with even lower ridership levels, due to the additional indirect benefits provided by reduced urban-peak automobile travel. Comprehensive evaluation can justify extensive bus lane networks in most cities, particularly rapidly-growing cities in developing countries.
For an application of this analysis see, “The Case For Bus-Only Lanes on Georgia Street: An Observational Study” (http://bit.ly/1NlTHxI )