Public Transportation

A Dynamic Holding Strategy to Improve Bus Schedule Reliability and Commercial Speed

Xuan, Yiguang
Argote, Juan
Daganzo, Carlos F.
2011

Bus systems are naturally unstable. Without control, the slightest disturbance to bus motion can cause buses to bunch, reducing schedule reliability. Holding strategies can eliminate this instability. However, the conventional schedule-based holding method requires too much slack time, which slows buses. This delays on-board passengers and increases operating costs. This paper studies a family of dynamic holding strategies that use the current state of all buses, as well as a virtual schedule. The virtual schedule is introduced whether the system is run with a published schedule or not. We...

Traffic Congestion in Networks, and Alleviating it with Public Transportation and Pricing

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

It has recently been demonstrated, both theoretically and experimentally, that the average flow and density of some urban traffic networks is related by a unique, reproducible curve known as the Macroscopic Fundamental Diagram (MFD). For networks in which vehicles cannot adaptively re-route to avoid congestion, this relationship is robust only when there are few vehicles on the network. As these types of networks become more crowded, trips are completed at a much lower rate than predicted by MFD theory. Thus, operating a network in congestion is extremely damaging on these networks. The...

Dynamic Bus Holding Strategies for Schedule Reliability: Optimal Linear Control and Performance Analysis

Xuan, Yiguang
Argote, Juan
Daganzo, Carlos F.
2011

As is well known, bus systems are naturally unstable. Without control, buses on a single line tend to bunch, reducing their punctuality in meeting a schedule. Although conventional schedule-based strategies that hold buses at control points can alleviate this problem these methods require too much slack, which slows buses. This delays on-board passengers and increases operating costs. It is shown that dynamic holding strategies based on headways alone cannot help buses adhere to a schedule. Therefore, a family of dynamic holding strategies that use bus arrival deviations from a virtual...

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-...

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...

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

Badia, Hugo
Daganzo, Carlos F.
2017

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%,...

How network structure can boost and shape the demand for bus transit

Badia, Hugo
Argote-Cabanero, Juan
2017

Conventional wisdom states that transit riders are averse to transfers and that consequently bus networks should be designed to limit their number. Probably as a result of this belief, many real bus systems try to connect as many origins and destinations as possible without transfers, so they are usually composed of long, circuitous routes with redundant overlapping sections – and the resulting bus map is hard to understand. If coverage is extensive, many routes are needed. Economics then prevents an agency from populating all routes with sufficient buses to provide attractively frequent...