ITS Berkeley

A Reliability-based Optimization Scheme for Maintenance Management in Large-Scale Bridge Networks

Hu, Xiaofei
Daganzo, Carlos F.
Madanat, Samer
2015

Incorporating network configurations in bridge management problems is computationally difficult. Because of the interdependencies among bridges in a network, they have to be analyzed together. Simulation-based numerical optimization techniques adopted in past research are limited to networks of moderate sizes. In this paper, a simple framework is developed to determine optimal maintenance plans for large networks with many bridges. The objective is to minimize disruption, specifically, the extra travel distance caused by potential bridge failures over a planning horizon and under a budget...

Automated System for Preventing Vehicle Bunching

Saloner, Dylan
Daganzo, Carlos F.
2015

The present invention contemplates a distributed automatic control system for preventing the vehicle bunching. Information of vehicle locations is automatically detected and used to determine the positions and velocities of vehicles along a route. Vehicles pass predetermined points, such as stations, along the route. Information about whether the vehicle skipped the station, arrived at the station, or departed from the station, is automatically calculated based on the position and velocity information. This information is distributed among the vehicles that belong to the same route....

Traffic Flow on Signalized Streets

Daganzo, Carlos F.
Lehe, Lewis J.
2016

This paper considers a signalized street of uniform width and blocks of various lengths. Its signals are pretimed in an arbitrary pattern, and traffic on it behaves as per the kinematic-wave/variational theory with a triangular fundamental diagram. It is shown that the long run average flow on the street when the number of cars on the street (i.e. the street’s density) is held constant is given by the solution of a linear program (LP) with a finite number of variables and constraints. This defines a point on the street’s macroscopic fundamental diagram. For the homogeneous special case...

Optimal Transit Service atop Ring-radial and Grid Street Networks: A Continuum Approximation Design Method and Comparisons

Chen, Haoyu
Cassidy, Michael J.
Daganzo, Carlos F.
2015

Two continuum approximation (CA) optimization models are formulated to design city-wide transit systems at minimum cost. Transit routes are assumed to lie atop a city’s street network. Model 1 assumes that the city streets are laid out in ring-radial fashion. Model 2 assumes that the city streets form a grid. Both models can furnish hybrid designs, which exhibit intersecting routes in a city’s central (downtown) district and only radial branching routes in the periphery. Model 1 allows the service frequency and the route spacing at a location to vary arbitrarily with the location’s...

Dynamic Control of Complex Transit Systems

Argote-Cabanero, Juan
Daganzo, Carlos F.
2015

This paper proposes a dynamic control method to overcome bunching and improve the regularity of fixed-route transit systems. The method uses a combination of dynamic holding and en-route driver guidance to achieve its objectives. It applies to systems with a mix of headway-based and schedule-based lines but it is evaluated for scheduled systems as this is the more challenging application. Improved schedule adherence is the goal. The method’s calculation complexity per piece of advice does not increase with system size. As a result, the method is scalable and can be used with large multi-...

Traffic Flow on Pedestrianized Streets

Daganzo, Carlos F.
Knoop, V. L.
2016

Giving pedestrians priority to cross a street enhances pedestrian life, especially if crosswalks are closely spaced. Explored here is the effect of this management decision on car traffic. Since queuing theory suggests that for a given pedestrian flux the closer the crosswalk spacing the lower the effect of pedestrians on cars, scenarios where pedestrians can cross anywhere should be best for both cars and pedestrians. This is the kind of pedestrianization studied. Analytic formulas are proposed for a pedestrianized street’s capacity, free-flow speed and macroscopic fundamental diagram. Of...

Zone Pricing in Theory and Practice

Daganzo, Carlos F.
Lehe, Lewis J.
2016

Amid growing recognition of the costs of downtown congestion and scarcity of revenues for new roads, congestion pricing for downtown areas -- a practice we call “zone pricing” -- has begun to receive wide attention. From 1975-2003, zone pricing failed to spread beyond Singapore, but by the 2000’s technological advances had made the practice more widely practical. Now London, Stockholm, Milan and Gothenburg have schemes of their own, and zone pricing is on the agenda in many world cities. The research summarized in this report has sought to advance practical knowledge of zone pricing in...

Coordinating Transit Transfers in Real Time

Daganzo, Carlos F.
Anderson, Paul
2016

Transfers are a major source of travel time variability for transit passengers. Coordinating transfers between transit routes in real time can reduce passenger waiting times and travel time variability, but these benefits need to be contrasted with the delays to on-board and downstream passengers, as well as the potential for bus bunching created by holding buses for transfers. We developed a dynamic holding strategy for transfer coordination based on control theory. We then obtained the optimal control strategy, where maximum holding time is a function of real-time estimates of bus...

Network Effects in Bus Transit: Evidence from Barcelona’s Nova Xarxa

Badia, Hugo
Argote-Cabanero, Juan
Daganzo, Carlos F.
2016

This paper shows that improving the structure of a bus transit network to facilitate transfers can boost and shape its demand. The idea is illustrated with data from the Nova Xarxa in Barcelona. Deployed in phases, the Nova Xarxa is shown to be attracting more demand than the network it replaces. The paper further shows that this growth is underpinned by transfers -- at the end of 2015, the percentage of trips that involved a transfer was approximately 26%, and it reached a maximum of 57% for line V7. The paper shows these numbers should increase considerably (to 44% and 66%, respectively...

Coordinating Transit Transfers in Real Time

Anderson, Paul
Daganzo, Carlos F.
2017

Transfers are a major source of travel time variability for transit passengers. Coordinating transfers between transit routes in real time can reduce passenger waiting times and travel time variability, but these benefits need to be contrasted with the delays to on-board and downstream passengers. This paper develops a dynamic holding strategy for transfer coordination where the decision to hold depends on real-time estimates of bus arrivals and passenger numbers and the uncertainty in these estimates. The strategy is then optimized based on the estimates. It is found that all the...