3,016 research outputs found

    A Multi-modal Trip Distribution Model

    Get PDF
    This paper presents a multimodal trip distribution function estimated and validated for the metropolitan Washington region. In addition, a methodology for measuring accessibility, which is used as a measure of effectiveness for networks, using the impedance curves in the distribution model is described. This methodology is applied at the strategic planning level to alternative HOV alignments to select alignments for further study and Right-of-Way preservation. .

    A three-dimensional macroscopic fundamental diagram for mixed bi-modal urban networks

    Get PDF
    Recent research has studied the existence and the properties of a macroscopic fundamental diagram (MFD) for large urban networks. The MFD should not be universally expected as high scatter or hysteresis might appear for some type of networks, like heterogeneous networks or freeways. In this paper, we investigate if aggregated relationships can describe the performance of urban bi-modal networks with buses and cars sharing the same road infrastructure and identify how this performance is influenced by the interactions between modes and the effect of bus stops. Based on simulation data, we develop a three-dimensional vehicle MFD (3D-vMFD) relating the accumulation of cars and buses, and the total circulating vehicle flow in the network. This relation experiences low scatter and can be approximated by an exponential-family function. We also propose a parsimonious model to estimate a three-dimensional passenger MFD (3D-pMFD), which provides a different perspective of the flow characteristics in bi-modal networks, by considering that buses carry more passengers. We also show that a constant Bus-Car Unit (BCU) equivalent value cannot describe the influence of buses in the system as congestion develops. We then integrate a partitioning algorithm to cluster the network into a small number of regions with similar mode composition and level of congestion. Our results show that partitioning unveils important traffic properties of flow heterogeneity in the studied network. Interactions between buses and cars are different in the partitioned regions due to higher density of buses. Building on these results, various traffic management strategies in bi-modal multi-region urban networks can then be integrated, such as redistribution of urban space among different modes, perimeter signal control with preferential treatment of buses and bus priority

    A dynamic ridesharing dispatch and idle vehicle repositioning strategy with integrated transit transfers

    Full text link
    We propose a ridesharing strategy with integrated transit in which a private on-demand mobility service operator may drop off a passenger directly door-to-door, commit to dropping them at a transit station or picking up from a transit station, or to both pickup and drop off at two different stations with different vehicles. We study the effectiveness of online solution algorithms for this proposed strategy. Queueing-theoretic vehicle dispatch and idle vehicle relocation algorithms are customized for the problem. Several experiments are conducted first with a synthetic instance to design and test the effectiveness of this integrated solution method, the influence of different model parameters, and measure the benefit of such cooperation. Results suggest that rideshare vehicle travel time can drop by 40-60% consistently while passenger journey times can be reduced by 50-60% when demand is high. A case study of Long Island commuters to New York City (NYC) suggests having the proposed operating strategy can substantially cut user journey times and operating costs by up to 54% and 60% each for a range of 10-30 taxis initiated per zone. This result shows that there are settings where such service is highly warranted

    Macroscopic modelling and robust control of bi-modal multi-region urban road networks

    Get PDF
    The paper concerns the integration of a bi-modal Macroscopic Fundamental Diagram (MFD) modelling for mixed traffic in a robust control framework for congested single- and multi-region urban networks. The bi-modal MFD relates the accumulation of cars and buses and the outflow (or circulating flow) in homogeneous (both in the spatial distribution of congestion and the spatial mode mixture) bi-modal traffic networks. We introduce the composition of traffic in the network as a parameter that affects the shape of the bi-modal MFD. A linear parameter varying model with uncertain parameter the vehicle composition approximates the original nonlinear system of aggregated dynamics when it is near the equilibrium point for single- and multi-region cities governed by bi-modal MFDs. This model aims at designing a robust perimeter and boundary flow controller for single- and multi-region networks that guarantees robust regulation and stability, and thus smooth and efficient operations, given that vehicle composition is a slow time-varying parameter. The control gain of the robust controller is calculated off-line using convex optimisation. To evaluate the proposed scheme, an extensive simulation-based study for single- and multi-region networks is carried out. To this end, the heterogeneous network of San Francisco where buses and cars share the same infrastructure is partitioned into two homogeneous regions with different modes of composition. The proposed robust control is compared with an optimised pre-timed signal plan and a single-region perimeter control strategy. Results show that the proposed robust control can significantly: (i) reduce the overall congestion in the network; (ii) improve the traffic performance of buses in terms of travel delays and schedule reliability, and; (iii) avoid queues and gridlocks on critical paths of the network

    Implementing Connections: The Benefits for Greater Philadelphia

    Get PDF
    This analysis utilizes DVRPC's modeling capabilities to illustrate and quantify the benefits of implementing the policies and goals defined in the Connections Plan, through a Plan scenario, compared to a continuation of our region's business-as-usual Trend scenario. Both scenarios are set in the horizon year of the Plan, 2035, and compared to each other and current conditions (2010)

    Geometrical and functional criteria as a methodological approach to implement a new cycle path in an existing Urban Road Network: A Case study in Rome

    Get PDF
    Most road accidents occur in urban areas and notably at urban intersections, where cyclists and motorcyclists are the most vulnerable. In the last few years, cycling mobility has been growing; therefore, bike infrastructures should be designed to encourage this type of mobility and reduce motorized and/or private transport. The paper presents a study to implement a new cycle path in the existing cycle and road network in Rome, Italy. The geometric design of the new path complies with Italian standards regarding the technical characteristics of bicycle paths, while the Highway Capacity Manual has been considered for the traffic analysis. In particular, a before-after approach has been adopted to examine and compare the traffic flow at more complex and congested intersections where the cycle path will pass. Trams, buses, cars, bikes and pedestrians were the traffic components considered in each analysis. The software package PTV VISSIM 8 allowed the simulations of traffic flows at traffic-light intersections; an original linear process has been proposed to model dynamic intelligent traffic controls, which are not admitted by the software used. The traffic analysis allowed the identification of the best option for each of the five examined intersections. Particularly, the maximum queue length value and the total number of passed vehicles have been considered in order to optimize the transport planning process. The results of this study highlight the importance of providing engineered solutions when a cycle path is implemented in a complex road network, in order to avoid negative impacts on the citizens and maximize the expected advantages

    2013-2014 Congestion Management Process (CMP) Supplemental Projects Status Memorandum

    Get PDF
    This memorandum is the seventh review of the status of supplemental projects for major Single Occupancy Vehicle (SOV) capacity-adding projects in the region's Transportation Improvement Programs (TIPs). The Delaware Valley Regional Planning Commission worked with project sponsors to identify or update Congestion Management Process (CMP) commitments for six projects, including five major SOV capacityadding projects in Pennsylvania that did not already have an approved table of supplemental commitments. Commitments for one project in New Jersey are updated in this memorandum. All projects reviewed were found to be making reasonable progress with supplemental projects in accordance with federal CMP regulations. The passage of Pennsylvania Act 89 of 2013 has led to the reactivation of many projects that were on hold for years due to lack of funding. Each of these projects was already in the project pipeline prior to being listed in the FY 2015 -- 2018 PA TIP for Final Design and Construction funds. Supplemental commitment tables for these projects are documented in this memorandu

    A Windowed Transportation Planning Model

    Get PDF
    This research develops and applies a transportation planning model that integrates regional and local area forecasting approaches. While regional models have the scope to model the interaction of demand and congestion, they lack the spatial detail of a local approach. Local approaches typically do not consider the feedback between new project traffic and existing levels of traffic. Using a window, which retains the regional trip distribution information and the consistency between travel demand and congestion, allows the use of a complete transportation network and block level traffic zones while retaining computational feasibility. By combining the two methods, a number of important policy issues can be addressed, including the implications of traffic calming, changes in flow due to alternative traffic operation schemes, the influence of micro-scale zoning changes on nearby intersections, the impact of TDM on traffic congestion, and the consequences of a suburban light rail line.transportation planning model, traffic impact study, travel demand model, intersection control, window .
    • …
    corecore