86 research outputs found
Short-Term Forecasting of Passenger Demand under On-Demand Ride Services: A Spatio-Temporal Deep Learning Approach
Short-term passenger demand forecasting is of great importance to the
on-demand ride service platform, which can incentivize vacant cars moving from
over-supply regions to over-demand regions. The spatial dependences, temporal
dependences, and exogenous dependences need to be considered simultaneously,
however, which makes short-term passenger demand forecasting challenging. We
propose a novel deep learning (DL) approach, named the fusion convolutional
long short-term memory network (FCL-Net), to address these three dependences
within one end-to-end learning architecture. The model is stacked and fused by
multiple convolutional long short-term memory (LSTM) layers, standard LSTM
layers, and convolutional layers. The fusion of convolutional techniques and
the LSTM network enables the proposed DL approach to better capture the
spatio-temporal characteristics and correlations of explanatory variables. A
tailored spatially aggregated random forest is employed to rank the importance
of the explanatory variables. The ranking is then used for feature selection.
The proposed DL approach is applied to the short-term forecasting of passenger
demand under an on-demand ride service platform in Hangzhou, China.
Experimental results, validated on real-world data provided by DiDi Chuxing,
show that the FCL-Net achieves better predictive performance than traditional
approaches including both classical time-series prediction models and neural
network based algorithms (e.g., artificial neural network and LSTM). This paper
is one of the first DL studies to forecast the short-term passenger demand of
an on-demand ride service platform by examining the spatio-temporal
correlations.Comment: 39 pages, 10 figure
Quantifying traffic emission reductions and traffic congestion alleviation from high-capacity ride-sharing
Despite the promising benefits that ride-sharing offers, there has been a
lack of research on the benefits of high-capacity ride-sharing services. Prior
research has also overlooked the relationship between traffic volume and the
degree of traffic congestion and emissions. To address these gaps, this study
develops an open-source agent-based simulation platform and a heuristic
algorithm to quantify the benefits of high-capacity ride-sharing with
significantly lower computational costs. The simulation platform integrates a
traffic emission model and a speed-density traffic flow model to characterize
the interactions between traffic congestion levels and emissions. The
experiment results demonstrate that ride-sharing with vehicle capacities of 2,
4, and 6 passengers can alleviate total traffic congestion by approximately 3%,
4%, and 5%, and reduce traffic emissions of a ride-sourcing system by
approximately 30%, 45%, and 50%, respectively. This study can guide
transportation network companies in designing and managing more efficient and
environment-friendly mobility systems
Deep Multi-View Spatial-Temporal Network for Taxi Demand Prediction
Taxi demand prediction is an important building block to enabling intelligent
transportation systems in a smart city. An accurate prediction model can help
the city pre-allocate resources to meet travel demand and to reduce empty taxis
on streets which waste energy and worsen the traffic congestion. With the
increasing popularity of taxi requesting services such as Uber and Didi Chuxing
(in China), we are able to collect large-scale taxi demand data continuously.
How to utilize such big data to improve the demand prediction is an interesting
and critical real-world problem. Traditional demand prediction methods mostly
rely on time series forecasting techniques, which fail to model the complex
non-linear spatial and temporal relations. Recent advances in deep learning
have shown superior performance on traditionally challenging tasks such as
image classification by learning the complex features and correlations from
large-scale data. This breakthrough has inspired researchers to explore deep
learning techniques on traffic prediction problems. However, existing methods
on traffic prediction have only considered spatial relation (e.g., using CNN)
or temporal relation (e.g., using LSTM) independently. We propose a Deep
Multi-View Spatial-Temporal Network (DMVST-Net) framework to model both spatial
and temporal relations. Specifically, our proposed model consists of three
views: temporal view (modeling correlations between future demand values with
near time points via LSTM), spatial view (modeling local spatial correlation
via local CNN), and semantic view (modeling correlations among regions sharing
similar temporal patterns). Experiments on large-scale real taxi demand data
demonstrate effectiveness of our approach over state-of-the-art methods.Comment: AAAI 2018 pape
A multi-functional simulation platform for on-demand ride service operations
On-demand ride services or ride-sourcing services have been experiencing fast
development in the past decade. Various mathematical models and optimization
algorithms have been developed to help ride-sourcing platforms design
operational strategies with higher efficiency. However, due to cost and
reliability issues (implementing an immature algorithm for real operations may
result in system turbulence), it is commonly infeasible to validate these
models and train/test these optimization algorithms within real-world ride
sourcing platforms. Acting as a useful test bed, a simulation platform for
ride-sourcing systems will be very important to conduct algorithm
training/testing or model validation through trails and errors. While previous
studies have established a variety of simulators for their own tasks, it lacks
a fair and public platform for comparing the models or algorithms proposed by
different researchers. In addition, the existing simulators still face many
challenges, ranging from their closeness to real environments of ride-sourcing
systems, to the completeness of different tasks they can implement. To address
the challenges, we propose a novel multi-functional and open-sourced simulation
platform for ride-sourcing systems, which can simulate the behaviors and
movements of various agents on a real transportation network. It provides a few
accessible portals for users to train and test various optimization algorithms,
especially reinforcement learning algorithms, for a variety of tasks, including
on-demand matching, idle vehicle repositioning, and dynamic pricing. In
addition, it can be used to test how well the theoretical models approximate
the simulated outcomes. Evaluated on real-world data based experiments, the
simulator is demonstrated to be an efficient and effective test bed for various
tasks related to on-demand ride service operations
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