The Thirty-Third AAAI Conference on Artificial Intelligence (AAAI-19)
Attention Based Spatial-Temporal Graph Convolutional Networks
for Traffic Flow Forecasting
Shengnan Guo,
1,2
Youfang Lin,
1,2,3
Ning Feng,
1,3
Chao Song,
1,2
Huaiyu Wan
1,2,3∗
1
School of Computer and Information Technology, Beijing Jiaotong University, Beijing, China
2
Beijing Key Laboratory of Traffic Data Analysis and Mining, Beijing, China
3
CAAC Key Laboratory of Intelligent Passenger Service of Civil Aviation, Beijing, China
{guoshn, yflin, fengning, chaosong, hywan}@bjtu.edu.cn
Abstract
Forecasting the traffic flows is a critical issue for researchers
and practitioners in the field of transportation. However, it
is very challenging since the traffic flows usually show high
nonlinearities and complex patterns. Most existing traffic
flow prediction methods, lacking abilities of modeling the dy-
namic spatial-temporal correlations of traffic data, thus can-
not yield satisfactory prediction results. In this paper, we
propose a novel attention based spatial-temporal graph con-
volutional network (ASTGCN) model to solve traffic flow
forecasting problem. ASTGCN mainly consists of three in-
dependent components to respectively model three tempo-
ral properties of traffic flows, i.e., recent, daily-periodic and
weekly-periodic dependencies. More specifically, each com-
ponent contains two major parts: 1) the spatial-temporal at-
tention mechanism to effectively capture the dynamic spatial-
temporal correlations in traffic data; 2) the spatial-temporal
convolution which simultaneously employs graph convolu-
tions to capture the spatial patterns and common standard
convolutions to describe the temporal features. The output of
the three components are weighted fused to generate the fi-
nal prediction results. Experiments on two real-world datasets
from the Caltrans Performance Measurement System (PeMS)
demonstrate that the proposed ASTGCN model outperforms
the state-of-the-art baselines.
Introduction
Recently, many countries are committed to vigorously de-
velop the Intelligent Transportation System (ITS) (Zhang
et al. 2011) to help for efficient traffic management. Traf-
fic forecasting is an indispensable part of ITS, especially on
the highway which has large traffic flows and fast driving
speed. Since the highway is relatively closed, once a conges-
tion occurs, it will seriously affect the traffic capacity. Traf-
fic flow is a fundamental measurement reflecting the state of
the highway. If it can be predicted accurately in advance, ac-
cording to this, traffic management authorities will be able
to guide vehicles more reasonably to enhance the running
efficiency of the highway network.
Highway traffic flow forecasting is a typical problem of
spatial-temporal data forecasting. Traffic data are recorded
at fixed points in time and at fixed locations distributed
∗
Corresponding author: hywan@bjtu.edu.cn
Copyright
c
2019, Association for the Advancement of Artificial
Intelligence (www.aaai.org). All rights reserved.
9:00 AM
5:00 PM
A
B
C
D
(a) Spatial influence of traffic flows at different times
(b) Temporal influence between traffic flows
0
t+2
t+1
t
t-1
t-4
t-2
time
flow
history
forecast
t-3
A
B
Influence
1
0
A
B
C
D
Figure 1: The spatial-temporal correlation diagram of traffic
flow
in continuous space. Apparently, the observations made at
neighboring locations and time stamps are not independent
but dynamically correlated with each other. Therefore, the
key to solve such problems is to effectively extracting the
spatial-temporal correlations of data. Fig. 1 demonstrates the
spatial-temporal correlations of traffic flows (also can be ve-
hicle speed, lane occupancy, etc.). The bold line between
two points represents their mutual influence strength. The
darker the color of line is, the greater the influence is. In the
spatial dimension (Fig. 1(a)), we can find that different loca-
tions have different impacts on A and even a same location
has varying influence on A as time goes by. In the temporal
dimension (Fig. 1(b)), the historical observations of differ-
ent locations have varying impacts on A’s traffic states at
different times in the future. In conclusion, the correlations
in traffic data on the highway network show strong dynamics
in both the spatial dimension and temporal dimension. How
to explore nonlinear and complex spatial-temporal data to
discover its inherent spatial-temporal patterns and to make
accurate traffic flow predictions is a very challenging issue.
Fortunately, with the development of the transportation
industry, many cameras, sensors and other information col-
lection devices have been deployed on the highway. Each
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