ITS Berkeley

Public Transportation Systems: Mini-Projects and Homework Exercises

Gonzales, Eric J.
Pilachowski, Josh
Gayah, Vikash V.
Cassidy, Michael
Daganzo, Carlos F.
2010

The Course Notes for a graduate-level course in Public Transportation include seven homework exercises and three mini-projects. Homework topics include optimization, point-to-point travel, congestion relief, designing a feeder bus system, demand-responsive transit, and bus pairings. The mini-projects involve bus rapid transit, designing a transit network, and bus and driver assignment.

On the Allocation of City Space to Multiple Transport Modes

Gonzales, Eric J.
Geroliminis, Nikolas
Cassidy, Michael J.
Daganzo, Carlos F.
2010

This paper analyzes urban multimodal transportation systems in an aggregated way. To describe the aggregate behavior of traffic in cities, use is made of an idea that is now receiving some attention: the macroscopic fundamental diagram (MFD). We demonstrate through simulation how the MFD can be used to monitor and control a real network, in this case a portion of San Francisco, using readily available input data. We then show how different modes interact on the same network and discuss how these interactions might be incorporated into an MFD for multimodal networks. The work unveils two...

Multimodal Transport in Nairobi, Kenya: Insights and Recommendations with a Macroscopic Evidence-Based Model

Gonzales, Eric J.
Chavis, Celeste
Li, Yuwei
Daganzo, Carlos F.
2011

The limited street network in Nairobi, Kenya, is crowded with cars and matatus (informal transit). This paper studies the existing traffic performance using traffic simulation. Despite the poorly connected, asymmetric street network, there is a consistent relationship between aggregated traffic variables for the city center, namely the number of vehicles circulating in the network and the rate at which trips reach their destinations. This relation is called a macroscopic fundamental diagram (MFD), and shows how the capacity of Nairobi's streets compares to the capacity of streets in...

Robust Stability Analysis of Decentralized Supply Chains

Ouyang, Yanfeng
Daganzo, Carlos F.
Kempf, Karl G.
Keskinocak, Pinar
Uzsoy, Reha
2011

This chapter summarizes recent findings on the bullwhip effect in decentralized multi-echelon supply chains based on a system-control approach. The influence of the supply chain operation (e.g., ordering policy and lead time) is separated from that of the customer demand. Robust results that hold for any customer demand are derived for both deterministically and stochastically operated chains. We demonstrate the importance of robust analysis. It is shown that instability is an inherent property of the system, e.g., of the ordering policies used by the suppliers, but it is independent of...

Macroscopic Fundamental Diagrams for Freeway Networks: Theory and Observation

Cassidy, Michael J.
Jang, Kitae
Daganzo, Carlos F.
2011

Macroscopic fundamental diagrams (MFDs), which relate the total time spent to the total distance traveled, are explored for freeway networks. It is proposed that these macrolevel relations should be observed if the data come from periods when all lanes on all links throughout the network are in either the congested or the uncongested regime. The theory pertains to freeway networks of any size, even when they are inhomogeneously congested and the data are variable in time. Analysis of vehicle trajectories from two freeway stretches of modest physical length supports this theory. Study...

Macroscopic Relations of Urban Traffic Variables: Bifurcations, Multivaluedness and Instability

Daganzo, Carlos F.
Gayah, Vikash V.
Gonzales, Eric J.
2011

Recent experimental work has shown that the average flow and average density within certain urban networks are related by a unique, reproducible curve known as the Macroscopic Fundamental Diagram (MFD). For networks consisting of a single route this MFD can be predicted analytically; but when the networks consist of multiple overlapping routes experience shows that the flows observed in congestion for a given density are less than those one would predict if the routes were homogeneously congested and did not overlap. These types of networks also tend to jam at densities that are only a...

Reducing Bunching with Bus-to-Bus Cooperation

Daganzo, Carlos F.
Pilachowski, Josh
2011

Schedule-based or headway-based control schemes to reduce bus bunching are not resilient because they cannot prevent buses from losing ground to the buses they follow when disruptions increase the gaps separating them beyond a critical value. (Following buses are then overwhelmed with passengers and cannot process their work quick enough to catch up.) This critical gap problem can be avoided, however, if buses at the leading end of such gaps are given information to cooperate with the ones behind by slowing down. This paper builds on this idea. It proposes an adaptive control scheme that...

Managing Evacuation Networks

Daganzo, Carlos F.
So, Stella K.
2011

This paper proposes a non-anticipative, adaptive, decentralized strategy for managing evacuation networks. The strategy is non-anticipative because it does not rely on demand forecasts, adaptive because it uses real-time traffic information, and decentralized because all the information is available locally. It can be used with a failed communication network. The strategy pertains to networks in which no links backtrack in the direction of increased risk. For these types of networks, no other strategy exists that can evacuate more people in any given time, or finish the evacuation in less...

Design and Implementation of Efficient Transit Networks: Procedure, Case Study and Validity Test

Estrada, M.
Roca-Riu, M.
Badia, H.
Robusté, F.
Daganzo, C. F.
2011

This paper presents and tests a method to design high-performance transit networks. The method produces conceptual plans for geometric idealizations of a particular city that are later adapted to the real conditions. These conceptual plans are generalizations of the hybrid network concept proposed in Daganzo (2010). The best plan for a specific application is chosen via optimization. The objective function is composed of analytic formulae for a concept‘s agency cost and user level of service. These formulae include as parameters key demand-side attributes of the city, assumed to be...

Effects of Turning Maneuvers and Route Choice on a Simple Network

Gayah, Vikash V.
Daganzo, Carlos F.
2011

A simple symmetric network that consists of two tangent rings on which vehicles obey the kinematic wave theory of traffic flow and can switch rings at the point of tangency is studied. An online adaptive simulation reveals that if there is any turning whatsoever, the two-ring system becomes unevenly loaded for densities greater than the optimal density, and reduces traffic flow. Furthermore, the two-ring system jams at significantly lower densities than the maximum density possible.