Bus Rapid Transit Systems Performance Analysis
E. Cipriani, S. Gori, M. Petrelli, Università ?Roma Tre?, IT
The present paper deals with a procedure for the evaluation of the performance of BRT systems for the definition of the variables that establish the performance of each different BRT system and the optimal field of existence of these elements.
Mobility problems represent a big issue in the modern cities. Such troubles derive from the quick increase in demand levels of people and goods, largely left to be carried by private transport. The obvious result is the congestion, implying an increase of travel times, and the corresponding raise of fuel consumption and, successively, of air pollution. Such occurrences are clearly not consistent with sustainable issues.
Sustainable mobility requires actions to:
1) reduce the need to travel (less trips generated);
2) reduce trip lengths;
3) encourage modal shift towards more sustainable modes such as transit system;
4) promote greater efficiency in the transport system.
The Bus Rapid Transit (BRT) system is increasing the presence in the world above all in the developing countries and it should play an important role to solve the points 3 and 4 previously reported, in particular, taking into account the financial constraints emphasized, also in developed countries by the recent world economical crisis.
Main key points of a BRT system rely on its economic sustainability deriving both from its easiness in the building phase and from its flexibility in the operative one. The systems vary in design, operations, usage, and effectiveness.
According to the BRT Implementation Guidelines from Federal Transit Administration (FTA), the BRT system is defined as a ?flexible, high performance rapid transit mode that combines a variety of physical, operating and system elements into a permanently integrated system with a quality image and unique identity?. This definition underlines the BRT?s flexibility and the wide variety of applications, each one tailored to a particular set of travel markets and physical environments.
The adoption of exclusive bus lanes, high-capacity vehicles, increased distance between stops, high frequency service, signal priority, rail-like stations, real time passenger information defines the BRT as a flexible and integrated system with a strong positive identity that evokes a unique image.
BRT system performance analysis
BRT systems are interested by a great deployment all over the world, in developing but also developed countries because, despite of large differences existing among these locations. Transit and, in particular BRT, is considered as a way to improve aggregate mobility through the more efficient use of road space, thus reducing traffic congestion.
Based on such topics, the present paper deals with a procedure for the evaluation of the performance of BRT systems and other issues about the capabilities of BRT to provide a network of high quality and high reliability services in medium-high demand corridors.
The final aim of the analysis procedure deals with the basic BRT system implementation problem: the definition of the variables that establish the performance of each different BRT system and the optimal field of existence of these elements.
The problem addressed involves the performance analysis by the point of view of both the operators in terms of commercial speed and fleet size and the users in terms of door-to-door travel time. The analysis is carried out using a theoretical approach with a transit system composed by a single route adopting a set of hypotheses about transit system and demand characteristics. The performance analysis involves also the study of a more complicated transit system in which there is a service, sharing the same route, composed by an express line and an all stops line. This service structure represents a common situation of the BRT system around the world.
The performance analysis of a BRT system carried out by the point of view of both the operators and the users permits to highlight the importance of the stop spacing as primary parameter. The evaluation procedure adopted permits to define an optimal, on the whole, value of stop spacing of about 800 m and, however, always higher than 400-500 m. The analysis performed about combined service highlights that this kind of service, with two lines using the same facility, represents an interesting and promising solution for long user trip distance (8 or more km) and high frequencies service (headway less than 5 min).
Association for European Transport