A Preliminary Analysis Over the Factors Related with the Possession of an Electric Bike

AbstractIn recent decades different studies focused on how to incentivize a shift from car to bicycle. In this context the electric bike is gaining more and more popularity. Because of its higher speed and longer reach, the e-bike could be an attractive alternative to the car. Through an online survey (together with a GPS tracking campaign and a weekly travel diary) conducted in the city of Ghent (Belgium) we define the profile of the e-bike users (age, income, ownership, etc…) and analyze their mobility habits (distance travelled, purpose of the trip, etc…). The initial results obtained from a travel diary survey show how the e-bike is highly used for commuting trips while for more occasional trips (at most once per week) the car is the preferred alternative. Moreover, the analysis of the changes in the mobility habits after the acquisition of the e-bike shows how the e-bike has mainly incorporated the trips performed by bike while also causing an increase of the frequency for some trips. Summarizing, in this paper we propose a preliminary analysis over the factors correlated with the ownership of an e-bike and an overview about how people changed their mobility habits after the acquisition of the e-bike

State of the art on the integration of dynamic traffic assignment and activity based models

The analysis of heavily loaded transportation networks requires continuous development of research on transportation models. The current state of the practice is to use static transportation models, even though they date from the 1950’s when congestion levels, economic and social activity patterns were radically different than today. In response to this, Activity-Based Modelling (ABM) and Dynamic Traffic Assignment (DTA) have been developed on parallel tracks. However, it is obvious that there is an interaction between activity scheduling and time-varying traffic conditions. The shortcomings of DTA and ABM may be solved by integrating the two facets, but only few researchers have explored the interface between DTA and ABM. This paper is an overview of the current state of the art on the integration of ABM and DTA, as well as the current developments on data gathering techniques for a combined model.status: publishe

An Implicit Solution Scheme for the Link Transmission Model

Dynamic network loading (DNL) models are at the core of a wide variety of optimization schemes and network analysis tools. In practice this calls for fast and efficient methods to calculate traffic states for various levels of accuracy and numerous adaptations to the boundary conditions. In this paper, we describe the Implicit Link Transmission Model (I-LTM) a dynamic network loading algorithm that avoids small update steps and is able to calculate adaptations of an existing solution efficiently. Within each update step, an implicit consistency problem between flow propagation and network constraints is formulated, resulting in a fixed point solution with appropriate network delays. In an iterative scheme, this consistency problem is solved using the constraints of a previous iteration. The algorithm is further optimized by limiting calculations to the part of the network that has changed. I-LTM allows for fast sensitivity analyses, optimization algorithms and calibration methods and it avoids numerical instabilities related to large time steps, typically observed in most DNL algorithms. This makes it beneficial in terms of calculation effort and robustness of the result.status: publishe

A TWO-STEP APPROACH FOR THE CORRECTION OF THE SEED MATRIX IN THE DYNAMIC DEMAND ESTIMATION

In this work deterministic and stochastic optimization methods are tested for solving the Dynamic Demand Estimation problem. All the adopted methods demonstrate the difficulty in reproducing the correct traffic regime, especially if the seed matrix is not sufficiently close to the real one. Therefore, in this paper a new and intuitive procedure to specify an opportune starting seed matrix is proposed: it is a two-step procedure based on the concept of dividing the problem into small-size problems, focusing on specific OD pairs in different steps. Specifically, the first step focuses on the optimization of a subset of OD variables (the ones who generate the higher flows or the ones who generate the bottlenecks on the network). In the second step the optimization works on all the OD pairs, using as starting matrix the matrix derived from the first step. In this way is possible to use a more performance optimization method for every step, improving the performance of the method and the quality of the result with respect to the classical “one-step” approach. The procedure has been tested on the real network of Antwerp, Belgium, demonstrating its efficacy in combination with different optimization methods

Adaptive control with moving actuators at motorway bottlenecks with connected and automated vehicles

Connected and automated vehicles (CAVs) have the potential to improve the operation of future road traffic systems. In this paper, we propose a control method that uses CAVs as dynamic actuators to improve the capacity at motorway bottlenecks robustly. The proposed approach has been designed for mixed traffic flow using the fundamental diagram model of mixed traffic flow as a control activation tool. In order to implement our approach, we assume that the availability of detectors at motorway are able to obtain the density in real-time. The idea is that assuming a certain percentage of CAVs presence on the road, such vehicles can be used as mobile actuators to perform speed coordination tasks. Furthermore, the aim is to transfer the delays observed at the bottlenecks upstream on the motorway, where the conditions are more homogeneous. The proposed approached can be generalized and used in bottleneck scenarios with or without additional inflow from an on-ramp. According to the designed control strategy, when the traffic density at the bottleneck satisfies the activation condition, the CAVs will shift to moving actuator mode and generate a new speed profile. The objective is to improve traffic flow at the downstream bottleneck and also smooth the upstream arrival vehicle speed, thus improving the overall throughput of the network. The method has been evaluated through microscopic simulation experiments conducted with scenarios on the real-case study, a motorway in Antwerp, Belgium. The results show significant improvements in reducing traffic density and improving travel speed both locally at the control area, as well as at network level. Comparative experiments under different penetration rates show that the proposed method remains robust to the percentage of CAVs on the road. Finally, it can significantly reduce vehicle delays and prevent over-congested conditions, and also improve the traffic flow rate, even for relatively low penetration rates of CAVs.ISSN:0968-090

A generic class of first order node models for dynamic macroscopic simulation of traffic flows

Node models for macroscopic simulation have attracted relatively little attention in the literature. Nevertheless, in dynamic network loading (DNL) models for congested road networks, node models are as important as the extensively studied link models. This paper provides an overview of macroscopic node models found in the literature, explaining both their contributions and shortcomings. A formulation defining a generic class of first order macroscopic node models is presented, satisfying a list of requirements necessary to produce node models with realistic, consistent results. Defining a specific node model instance of this class requires the specification of a supply constraint interaction rule and (optionally) node supply constraints. Following this theoretical discussion, specific macroscopic node model instances for unsignalized and signalized intersections are proposed. These models apply an oriented capacity proportional distribution of the available supply over the incoming links of a node. A computationally efficient algorithm to solve the node models exactly is included.Macroscopic node model Dynamic network loading Dynamic traffic assignment