A model for holding strategy in public transit systems with real-time information

Holding strategies are among the most commonly used operation-control strategies in public transit systems. These strategies are most effective when used to control services characterized by high frequency. In this paper, a mathematical model for a holding control strategy is developed. Particularly, this model uses real-time information of locations of buses along a specified route. The objective of the developed model is to minimize the waiting time of passengers at all stops on that route. Furthermore, the model developed in this paper is characterized by the flexibility of adopting situations where bus occupancy could be either high, or low. A heuristic is developed to circumvent the complexity of the solution for the problem described. Numerical examples and computational results are presented and discussed.     

A model for development of optimized feeder routes and coordinated schedules—A genetic algorithms approach

Many attempts have been made to solve bus route network design problems by splitting it in two stages, one for routing and the other for scheduling. Some researchers have made attempts to solve network design problems using non-traditional optimization techniques also, but not much has been done on modelling coordinated operations involving transfers from one mode to another. In this research, feeder routes and frequencies leading to schedule coordination of feeder buses with main transit are developed simultaneously using genetic algorithms. The coordinated schedules of feeder buses are determined for the existing given schedules of main transit. Thus the developed feeder routes and schedules are complementary to each other. As a case study the Dun Laoghaire Dublin Area Rapid Transit (DART) (heavy rail suburban service) station of Dublin in Ireland is selected. Finally the outcome of the research is a generated feeder route network for feeder buses and coordinated schedules of feeder buses for the existing schedules of DART at the selected station. The results of the proposed model indicate improved load factors on developed routes and also the overall load factor is also improved considerably as compared to the authors’ earlier model.     

The maxisum and maximin-maxisum HAZMAT routing problems

We design routes for transportation of hazardous materials (HAZMAT) in urban areas, with multiple origin-destination pairs. First, we introduce the maxisum HAZMAT routing problem, which maximizes the sum of the population-weighted distances from vulnerable centers to their closest point on the routes. Secondly, the maximin-maxisum HAZMAT routing problem trades-off maxisum versus the population-weighted distance from the route to its closest center. We propose efficient IP formulations for both NP-Hard problems, as well as a polynomial heuristic that reaches gaps below 0.54% in a few seconds on the real case in the city of Santiago, Chile.     

Congestion pricing,transit subsidies and dedicated bus lanes: Efficient and practical solutions to congestion

We analyze urban congestion management policies through numerical analysis of a simple model that: allows users to choose between car, bus or an outside option (biking); consider congestion interactions between cars and buses; and allow for optimization of frequency, vehicle size, spacing between stops and percentage of capacity to be dedicated to bus lanes. We compare resulting service levels, social welfare and consumer surplus for a number of different policies and find that: (i) dedicated bus lanes is a better stand-alone policy than transit subsidization or congestion pricing. The latter is marginally better than subsidization but has a negative impact in consumer surplus. (ii) Efficient transit subsidies are quite large since in many cases first-best transit price is negative; establishing dedicated bus lanes or implementing congestion pricing render subsidies unnecessary for high demand levels. (iii) Both subsidization and dedicated bus lanes would count with public support while congestion pricing would probably encounter opposition. (iv) Transit subsidies and/or congestion pricing do not induce large changes on optimal bus size, frequency, circulation speeds and spacing between stops in mixed-traffic conditions: dedicated bus lanes do. (v) In all cases analyzed, revenues from congestion pricing are enough to cover transit subsidies; the optimal percentage of capacity that should be devoted for bus traffic is around one third.     

Generation and design heuristics for zonal express services

A methodology is presented for designing zonal services for a bus corridor, in which buses visit all stops in a route’s initial and final segments, skipping all stops in between. Two heuristics are described, one for congested (binding capacity) and other for uncongested cases. An experiment on a bidirectional corridor shows that the heuristics can find savings in social costs of 6.6% and 10.3% when compared to an express-service-only solution. We also show that, in some cases, the zonal service design problem can be solved analytically, outperforming the heuristics. This suggests the two approaches could be employed in tandem.     

Moving freight on public transit: Best practices,challenges, and opportunities

Freight on Transit (FOT) refers to an operational strategy where public transit vehicles and/or infrastructure are used to move freight. Examples include moving goods alongside passengers on buses, attaching cargo trailers to transit vehicles, and operating freight vehicles between trains on subway lines. This paper describes the methods and results of a three-round Delphi study engaging 34 transportation experts to explore challenges and opportunities of FOT and to conceptualize and evaluate potential FOT operations in Toronto. Traditional Delphi methods were used for the exploration of FOT challenges and opportunities, and a modified approach was formulated to integrate experts' opinions and develop new FOT concepts for Toronto. The results support previous claims that technical challenges of FOT may be easier to overcome than institutional barriers. Evaluation of potential FOT operating strategies in Toronto suggests that while the current public transit network does not have capacity to support additional movements, there may be realistic opportunities to include freight service in future projects as a means of offsetting operating costs and reducing the impacts of goods movements.     

Eco-driving by replicating best driving practices

Some transit companies have reduced up to 25% of their fuel consumption by training their drivers on eco-driving. We propose to further reduce fuel consumption by using best driving practices, which consist of guiding drivers on the recommended ranges of vehicle speed and engine RPM that lead to minimum fuel consumptions. These recommendations are obtained by monitoring the engine operational parameters used by drivers who have shown the lowest fuel consumption while driving vehicles of similar technology and running on the same section of the road. To demonstrate the applicability of this alternative, we monitored a fleet of 15 transit buses of recent technology serving a ～72-km long route of general characteristics during eight months of normal operation. For each kilometer, trips with the lowest fuel consumption were selected, and their interquartile ranges of RPM and speed were obtained. Then, a well-trained driver in eco-driving traveled over the same road with same type of buses, using these recommended ranges. Using his eco-driving training, he obtained a 0.5% reduction in fuel consumption with respect to the average of the population, and by using the best driving practices, his savings increased up to 10.1%. These savings were linked to an increase in the average energy efficiency of the engine from 27.6% to 28.9%, which demonstrates that when drivers use these best driving practices, they tend to operate the engine under conditions closer to the load—RPM engine area of engine highest efficiency.     

A tabu search heuristic for the heterogeneous vehicle routing problem on a multigraph

We study a time-constrained heterogeneous vehicle routing problem on a multigraph where parallel arcs between pairs of vertices represent different travel options based on criteria such as time, cost, and distance. We formulate the problem as a mixed-integer linear programming model and develop a tabu search heuristic that efficiently addresses computational challenges due to parallel arcs. Numerical experiments show that the heuristic is highly effective and that freight operators can achieve advantages in cost and customer service by considering alternative paths, especially when route duration limits are restrictive and/or when vehicles of smaller capacity are dispatched to serve remote customers.     

Analysis on bike-share ridership for origin-destination pairs: Effects of public transit route characteristics and land-use patterns

Studies on bike-share programs have dramatically increased during the past decades. While numerous studies have examined various factors affecting bike-share demand at the station-level, few attempts have been made to understand bike-share ridership at the origin-destination (OD) level due to technical difficulties. The objective of this study is to examine whether existing public transit characteristics affect bike-share ridership at OD-level. We combined three datasets: (1) bike-share ridership data, (2) land-use and bike-transit infrastructure, and (3) bike-transit route characteristics between OD pairs of bike stations. Zero-inflated negative binomial (ZINB) regression models were used for the analysis. Our results showed that the travel distance between OD bike stations, land-use compositions, and the existence of bike-friendly infrastructures were significant factors determining bike-share ridership at the OD-level. In particular, a longer duration of public transit trips than bike-share, and more transit transfers, were associated with bike-share ridership. Further, this study showed that bike-share and public transit might compete with or promote each other, even within the city. The study's findings suggest that the relative efficiency of bike-share compared to public transit is highly associated with bike-share demand and help to increase the utility of bike-share system in response to several limitations of existing public transit networks.     

Restating modal investment priority with an improved model for public transport analysis

We compare analytically and numerically the optimised performance of different urban public transport modes for three objectives: total cost minimisation, profit maximisation, and welfare maximisation. We find that under optimal operation, buses provide lower waiting time and operator costs, therefore the only possible advantage for rail is providing a lower in-vehicle time cost if trains are faster. Using Australian data, we found that bus rapid transit provides a lower total cost, higher profit and welfare, up to their capacity. Introducing passengers dislike of crowding and train-specific attraction elements might make Heavy Rail the most cost effective mode for high levels of demand.     

Exploring built environment correlates of walking distance of transit egress in the Twin Cities

Most studies on walking distance to transit stops either emphasize transit access or do not distinguish transit access and egress. Furthermore, environmental correlates of walking distance may differ by stop location. Using the 2010 Transit Onboard Survey in the Minneapolis and St. Paul Metropolitan Area, this study develops four models to compare the effects of the built environment around transit stops on walking distance of transit egress. Job density is negatively correlated with walking distance, consistent in all four models. Other built environment variables exhibit different impacts by stop location. Particularly, land use mix has positive impacts on walking distance for stops outside of downtown and suburban employment centers whereas job density is more important for suburban centers. Job accessibility and the number of intersections have significant effects on stops within downtown areas but have no significant impacts on stops outside of downtown areas. The number of transit stops has opposite impacts on walking distance for stops within and outside of downtown. Moreover, the built environment tends to have a larger impact on walking distance in downtown areas than non-downtown areas. We then discuss the implications for stop area land use planning and transit stop location choice.     

Route choice behavior in a radial structured urban network: Do people choose the orbital or the route through the city center?

We use a license plate survey to study route choice through the city center of a medium-sized Dutch city, in which car drivers can basically choose between the orbital and center ring. For a sample of 1397 trips, we fitted a multinomial logit regression model. According to this model, route choice is relatively little influenced by actual travel time. This corresponds with the fact that many drivers did not choose the shortest time route. Travel distance in combination with one “route type velocity” for all orbital routes, and one route type velocity for all center routes is the most decisive factor. The route type velocity indicates how fast and attractive routes of that type are (being perceived). The results support the hypothesis that orbital routes are more attractive as these routes avoid the busy city center. This effect is however partly offset by the fact that drivers also prefer routes in the direction of their destination. These direct routes are mainly center routes. The results show the importance of considering complete routes in relation to their location and not only as a set of links and nodes when modeling route choice.     

Dense,mixed-use,walkable urban precinct to support sustainable transport or vice versa? A model for consideration from Perth,Western Australia

ABSTRACT

Within the majority of the literature on sustainable transport, it is accepted as ideal to arrange new urban growth in close proximity to major public transit services. While the literature on this subject of transit-oriented developments (TOD) is positive and optimistic, for the most part such assertions are conjectural. This article will attempt to fill this gap by revealing a modeling process undertaken for a local area's reurbanization project to understand the potential and limitations of several modes of transport to support the increased activity density in the precincts. Several of the most standardized policy levers were employed, such as parking ratios and mix of use and building height, and contrasted with the trip generation and transit mode's hourly capacity to reveal potential real-estate yields. The outcomes indicate not only the immediate yields but also the capacity for urban transformation due to each level of sustainable transport investments. The model is unique in that the capacity, parking ratios, and assumptions are highly transparent.     

Designing robust routes for demand-responsive transport systems

In this study, we propose an innovative concept for robust demand-responsive transportation (DRT) systems where vehicles may deviate from the planned route to accept late requests, which are unknown during the planning stage. We propose a new formulation of the problem as a stochastic mixed integer program and describe an efficient heuristic procedure that embeds a tabu search approach in a scheme for merging different scenario solutions. The computational results demonstrate the validity of the heuristic and provide useful managerial insights into DRT systems, thereby showing the value of incorporating uncertainty into the planning process.     

A novel origin destination based transit supply index: Exploiting the opportunities with big transit data

Quantifying transit resources and its networkwide temporal distribution is needed for the informed transit planning and operations decisions. One effective way to estimate the transit resource provision to a zone is to calculate the transit supply index. However, in literature, Supply Index (SI) is modelled considering the transit services allocated to a zone and ignores the quality and quantity of the supply provided between two zones. Addressing this need, this paper proposes a novel origin-destination based supply index (odSI) that incorporates a) zonal characteristics such as transit routes operate in origin zone, number of trips made by those routes, walk buffer areas of transit stops, and the total area of the zone; b) the quality of the service provided in terms of the average speed and route straightness ratio; and c) origin-destination dependent variables such as the minimum number of transfers needed to travel between two zones, the average transit speed between those zones, straightness of transit routes, and total available capacity. As proof of concept, the proposed odSI model is applied on the real network from Brisbane, Australia, at Statistical Area-2 level. The odSI results for 136 × 136 zonal pairs are presented for four different time periods (two peak and two off-peak periods). Furthermore, detailed analysis is carried for a zone, Grange, as an origin and the remaining 135 zones as destinations. The applicability of the proposed odSI model on Brisbane demonstrates its capability to provide valuable insights for an extensive network, which can help planners visualise and improve the complex and cumbersome networks in a more effective manner.     

Uncovering the spatially heterogeneous effects of shared mobility on public transit and taxi

A Mixed Geographically Weighted Regression (GWR) model is applied to explore the effects of shared mobility trips on taxi and public transit ridership at the macro-level. Several essential variables, including socioeconomic, transportation, network, and land use data, are set as the causal factors. The experiment is conducted using the smart card data, vehicle GPS trajectories, and vehicle order data collected in Shenzhen City, China. We show that the Mixed GWR outperforms the basic GWR in model fitting and capturing the unobserved heterogeneity. The spatial analysis reveals that bike-sharing addresses the “last-mile” and “first-mile” problems to bus and metro in the urban periphery. It substitutes the bus and taxis in short-distance journeys in the city center. However, the over-placement of bike-sharing in some regions limits the flexibility of bike-sharing connections to the metro. In the city center, ride-hailing fills the gaps in bus coverage and competes with the metro. In the peripheral areas, ride-hailing replaces buses and improves the accessibility to metro stations. The transportation policy increases the cooperation between ride-hailing and taxis citywide, although competitions in few regions need to be solved. The abovementioned results provide policy suggestions to optimize the allocation of local transportation resources.     

Incorporating location,routing and inventory decisions in supply chain network design

This paper for the first time presents a novel model to simultaneously optimize location, allocation, capacity, inventory, and routing decisions in a stochastic supply chain system. Each customer’s demand is uncertain and follows a normal distribution, and each distribution center maintains a certain amount of safety stock. To solve the model, first we present an exact solution method by casting the problem as a mixed integer convex program, and then we establish a heuristic method based on a hybridization of Tabu Search and Simulated Annealing. The results show that the proposed heuristic is considerably efficient and effective for a broad range of problem sizes.     

The digital matatu project: Using cell phones to create an open source data for Nairobi's semi-formal bus system

In many of the world's growing cities, semi-formal buses form the basis of public transit systems. However, little open and standardized data exist on these systems. The Digital Matatus project in Nairobi, Kenya set out to test whether the geo-locative capabilities of mobile technology could be used to collect data on a semi-formal transit system and whether that data could be translated into the General Transit Feed Specification (GTFS) data standard for wider use. The results of this work show that mobile technologies, particularly mobile phones, which are increasingly prevalent in developing countries, can indeed be used effectively to collect and deliver data in a modified GTFS format for semi-formal transit. Perhaps more importantly, through our work in Nairobi, we were able to identify the benefits and technical needs for developing data on semi-formal transit. Overall, the work illustrates (1) how the GTFS can be adapted to semi-formal systems and used by other cities with such transit systems, (2) that there is demand from technologists as well as transport communities for comprehensive data on semi-formal transit, (3) that releasing the data openly in the GTFS standard format can help to encourage the development of transportation applications, and (4) that including the entire transit community during the data development can create a community of users and mechanisms for institutionalizing a process of data updating and sharing. The engagement strategies our research team developed around the data collection process in Nairobi became just as important as the resulting data it produced.     

A social equity lens on bus bridging and ride-hailing responses to unplanned subway disruptions

During subway disruptions, commuters are often left stranded while they wait for bus bridging services. Some are able to change their mode of transport midway through their trip, often by requesting a ride-hailing service like Uber or Lyft if they are affordable. Many agencies use in-service buses to provide bus bridging services during subway disruptions, leading to reduced levels of service for other bus riders. Bus bridging policies and the affordability of ride-hailing raise questions regarding the equitable distribution of transit capacity during subway disruptions. After analyzing 78 major subway disruptions in Toronto, we found that bus routes serving disadvantaged populations were more likely to be negatively impacted by diversions for subway disruptions, than routes operating in more affluent areas of the city. We also found that ride-hailing demand increased during subway disruptions, but not in the more disadvantaged neighbourhoods. The research points to inequalities in how transit riders are impacted by subway disruptions, and further identifies how ride-hailing actually serves to reinforce these inequalities, rather than ameliorate them.     

Anatomy of a new dollar van route: Informal transport and planning in New York City

Despite nearly eight million rides per day on formally planned and legally sanctioned buses and subways, dollar vans provide service that shadow some of the busiest bus lines in Brooklyn and Queens. Dollar vans are an informal transport service that occupy an awkward liminal space between legal and illegal—some are licensed and some are not, but all dollar vans operate illegally. It is this legal confusion that renders them informal. It is because of this informality that dollar van operators and drivers can also adapt their routes and service as they deem necessary. This “generative” mode of planning introduces a second dimension of informality; however, I argue that dollar van operators follow a similar logic as formal transportation operators when planning service. I demonstrate this by examining the case of a dollar van operator in Brooklyn developing a new route. I juxtapose his method with that of bus planners from the Metropolitan Transportation Authority (MTA) to show how both groups of planners rely on prompts they encounter, be it anecdotal stories about West Indians in Flatbush moving away or an angry letter from a state legislator, rather than a systematic approach that is taught in classrooms. By examining the planning of a new dollar van route in Brooklyn, I trace the operator's planning process and compare his data against quantitative datasets to show that his generative planning process is supported by the quantitative data and deepens its meaning when combined with his local knowledge. Seen in this light, it is clear that the distance between informal and formal transit is artificial rather than inherent.