4,807 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
RiskOracle: A Minute-level Citywide Traffic Accident Forecasting Framework
Real-time traffic accident forecasting is increasingly important for public
safety and urban management (e.g., real-time safe route planning and emergency
response deployment). Previous works on accident forecasting are often
performed on hour levels, utilizing existed neural networks with static
region-wise correlations taken into account. However, it is still challenging
when the granularity of forecasting step improves as the highly dynamic nature
of road network and inherent rareness of accident records in one training
sample, which leads to biased results and zero-inflated issue. In this work, we
propose a novel framework RiskOracle, to improve the prediction granularity to
minute levels. Specifically, we first transform the zero-risk values in labels
to fit the training network. Then, we propose the Differential Time-varying
Graph neural network (DTGN) to capture the immediate changes of traffic status
and dynamic inter-subregion correlations. Furthermore, we adopt multi-task and
region selection schemes to highlight citywide most-likely accident subregions,
bridging the gap between biased risk values and sporadic accident distribution.
Extensive experiments on two real-world datasets demonstrate the effectiveness
and scalability of our RiskOracle framework.Comment: 8 pages, 4 figures. Conference paper accepted by AAAI 202
A Survey on Graph Neural Networks in Intelligent Transportation Systems
Intelligent Transportation System (ITS) is vital in improving traffic
congestion, reducing traffic accidents, optimizing urban planning, etc.
However, due to the complexity of the traffic network, traditional machine
learning and statistical methods are relegated to the background. With the
advent of the artificial intelligence era, many deep learning frameworks have
made remarkable progress in various fields and are now considered effective
methods in many areas. As a deep learning method, Graph Neural Networks (GNNs)
have emerged as a highly competitive method in the ITS field since 2019 due to
their strong ability to model graph-related problems. As a result, more and
more scholars pay attention to the applications of GNNs in transportation
domains, which have shown excellent performance. However, most of the research
in this area is still concentrated on traffic forecasting, while other ITS
domains, such as autonomous vehicles and urban planning, still require more
attention. This paper aims to review the applications of GNNs in six
representative and emerging ITS domains: traffic forecasting, autonomous
vehicles, traffic signal control, transportation safety, demand prediction, and
parking management. We have reviewed extensive graph-related studies from 2018
to 2023, summarized their methods, features, and contributions, and presented
them in informative tables or lists. Finally, we have identified the challenges
of applying GNNs to ITS and suggested potential future directions
Spatiotemporal Graph Neural Networks with Uncertainty Quantification for Traffic Incident Risk Prediction
Predicting traffic incident risks at granular spatiotemporal levels is
challenging. The datasets predominantly feature zero values, indicating no
incidents, with sporadic high-risk values for severe incidents. Notably, a
majority of current models, especially deep learning methods, focus solely on
estimating risk values, overlooking the uncertainties arising from the
inherently unpredictable nature of incidents. To tackle this challenge, we
introduce the Spatiotemporal Zero-Inflated Tweedie Graph Neural Networks
(STZITD-GNNs). Our model merges the reliability of traditional statistical
models with the flexibility of graph neural networks, aiming to precisely
quantify uncertainties associated with road-level traffic incident risks. This
model strategically employs a compound model from the Tweedie family, as a
Poisson distribution to model risk frequency and a Gamma distribution to
account for incident severity. Furthermore, a zero-inflated component helps to
identify the non-incident risk scenarios. As a result, the STZITD-GNNs
effectively capture the dataset's skewed distribution, placing emphasis on
infrequent but impactful severe incidents. Empirical tests using real-world
traffic data from London, UK, demonstrate that our model excels beyond current
benchmarks. The forte of STZITD-GNN resides not only in its accuracy but also
in its adeptness at curtailing uncertainties, delivering robust predictions
over short (7 days) and extended (14 days) timeframes
An Urban Traffic Flow Fusion Network Based on a Causal Spatiotemporal Graph Convolution Network
Traffic flow prediction is an important part of intelligent transportation systems. In recent years, most methods have considered only the feature relationships of spatial dimensions of traffic flow data, and ignored the feature fusion of spatial and temporal aspects. Traffic flow has the features of periodicity, nonlinearity and complexity. There are many relatively isolated points in the nodes of traffic flow, resulting in the features usually being accompanied by high-frequency noise. The previous methods directly used the graph convolution network for feature extraction. A polynomial approximation graph convolution network is essentially a convolution operation to enhance the weight of high-frequency signals, which lead to excessive high-frequency noise and reduce prediction accuracy to a certain extent. In this paper, a deep learning framework is proposed for a causal gated low-pass graph convolution neural network (CGLGCN) for traffic flow prediction. The full convolution structure adopted by the causal convolution gated linear unit (C-GLU) extracts the time features of traffic flow to avoid the problem of long running time associated with recursive networks. The reduction of running parameters and running time greatly improved the efficiency of the model. The new graph convolution neural network with self-designed low-pass filter was able to extract spatial features, enhance the weight of low-frequency signal features, suppress the influence of high-frequency noise, extract the spatial features of each node more comprehensively, and improve the prediction accuracy of the framework. Several experiments were carried out on two real-world real data sets. Compared with the existing models, our model achieved better results for short-term and long-term prediction.© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
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