Organizations: Department of Infrastructure Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, VIC 3010, Australia
Human-centric traffic signal control in corridor networks must increasingly account for multimodal travelers, particularly high-occupancy public transportation, rather than focusing solely on vehicle-centric performance. This paper proposes STDSH-MARL (Spatio-Temporal Dual-Stage Hypergraph based Multi-Agent Reinforcement Learning), a multi-agent deep reinforcement learning framework that follows a centralized training and decentralized execution paradigm. The proposed method captures spatio-temporal dependencies through a novel dual-stage hypergraph attention mechanism that models interactions across both spatial and temporal hyperedges. In addition, a hybrid discrete action space is introduced to jointly determine the next signal phase configuration and its corresponding green duration, enabling more adaptive signal timing decisions. Experiments conducted on a corridor network under five traffic scenarios demonstrate that STDSH-MARL achieves strong overall multimodal performance, with substantial and relatively consistent reductions in tram waiting time, while improvements in bus waiting time are more variable across traffic scenarios. These results highlight the trade-off among overall network efficiency, tram priority, and bus service quality. Compared with state-of-the-art baseline methods, the proposed approach achieves superior overall performance. Further ablation studies confirm the contribution of each component of STDSH-MARL, with temporal hyperedges identified as the most influential factor driving the observed performance gains.
Figures & tables
Figure 1: Overview of the proposed STDSH-MARL framework for multimodal corridor traffic signal control.
Traffic Simulation
References
Quantity
SUMO
Wang et al. (2021a) ; Li et al. (2021) ; Su et al. (2023) ; Song et al. (2024) ; Wang et al. (2024b) ; Bie et al. (2024) ; Yang (2023) ; Yang et al. (2021) ; Ren et al. (2024) ; Xu et al. (2024) ; Zhang et al. (2022b) ; Hu and Li (2024) ; Tan et al. (2020) ; Chu et al. (2019) ; Wu et al. (2020b) ; Bokade et al. (2023) ; Ge et al. (2021) ; Luo et al. (2024) ; Liu and Li (2023) ; Nie et al. (2025) ; Jia and Ji (2025) ; Fereidooni et al. (2025) ; Shen (2025) ; Chu et al. (2016) ; Ma and Wu (2020) ; Tao et al. (2023)
26
CityFlow
Zhu et al. (2023) ; Liu et al. (2023a) ; Wu et al. (2022) ; Liu et al. (2023b) ; Zhang et al. (2022a) ; Wang et al. (2020b) ; Liu et al. (2025) ; Lai et al. (2025) ; Satheesh and Powell (2025) ; Wang et al. (2025)
10
VISSIM
Jiang et al. (2021) ; Wang et al. (2021b) ; Wu et al. (2020a) ; Lee et al. (2019) ; Zhang et al. (2025)
5
Aimsun
Abdoos (2020) ; Yoon et al. (2025)
2
Paramics
El-Tantawy et al. (2013)
1
Not mentioned
Wang et al. (2020a)
1
Table 1: Summary of traffic simulation environments
Reward Components
References
Quantity
Queue length (veh)
Zhu et al. (2023) ; Liu et al. (2023a) ; Wang et al. (2020a) ; Liu et al. (2023b) ; Tan et al. (2020) ; Bokade et al. (2023) ; Zhang et al. (2022a) ; Wang et al. (2020b) ; Fereidooni et al. (2025) ; Liu et al. (2025) ; Lai et al. (2025) ; Chu et al. (2016) ; Wang et al. (2025)
13
Waiting time (veh)
Wang et al. (2024b) ; Yang (2023) ; Yang et al. (2021) ;
5
Queue length (veh)
Chu et al. (2019) ; Liu and Li (2023)
Difference of queue lengths between two consecutive timesteps (veh)
Jiang et al. (2021) ; Luo et al. (2024)
2
Waiting time (veh)
Wu et al. (2022) ; Xu et al. (2024)
2
Throughput (veh)
Hu and Li (2024)
1
Table 2: Summary of factors considered in reward mechanism for each reference (i)
Reward Components
References
Quantity
Travel time delay (veh)
Song et al. (2024)
1
Queue length (veh)
Throughput (veh)
Waiting time (veh)
Bie et al. (2024)
1
Queue length (veh)
Throughput (veh)
Table 3: Summary of factors considering for reward mechanism for each reference (ii)
DRL Framework
References
Quantity
Q-learning
Zhu et al. (2023) ; Abdoos (2020) ; El-Tantawy et al. (2013) ; Chu et al. (2016)
4
DQN
Wang et al. (2021a) ; Wang et al. (2024b) ; Bie et al. (2024) ; Liu et al. (2023a) ; Xu et al. (2024) ; Wang et al. (2021b) ; Tan et al. (2020) ; Wu et al. (2020a) ; Zhang et al. (2022a) ; Lee et al. (2019) ; Liu and Li (2023) ; Wang et al. (2020b) ; Fereidooni et al. (2025) ; Lai et al. (2025) ; Tao et al. (2023)
15
QMIX
Liu et al. (2023b) ; Bokade et al. (2023) ; Liu et al. (2025)
3
DDQN
Hu and Li (2024) ; Wang et al. (2020a)
2
DDDQN
Jiang et al. (2021)
1
Table 4: Summary of value-based DRL frameworks
DRL Framework
References
Quantity
PPO
Ren et al. (2024) ; Zhang et al. (2022b) ; Luo et al. (2024) ; Nie et al. (2025) ; Fereidooni et al. (2025) ; Satheesh and Powell (2025)
6
COMA Policy Gradient
Song et al. (2024)
1
Table 5: Summary of policy-based DRL frameworks
DRL Framework
References
Quantity
A2C
Su et al. (2023) ; Wu et al. (2022) ; Chu et al. (2019) ; Ma and Wu (2020)
4
A3C
Wu et al. (2022)
1
Actor-Critic
Yang (2023) ; Yang et al. (2021)
2
DDPG
Li et al. (2021) ; Wu et al. (2020b) ; Jia and Ji (2025) ; Shen (2025) ; Yoon et al. (2025)
5
SAC
Ge et al. (2021) ; Zhang et al. (2025) ; Wang et al. (2025)
3
Table 6: Summary of hybrid-based DRL frameworks
Figure 2: Overview of STDSH-MARL: DSHA learns a hypergraph-level embedding from spatial and temporal hyperedges for a centralized critic, while decentralized agents act from local state representations in a VISSIM-simulated corridor.
Type
Features
Vehicle number
Total vehicle number, number of buses, number of trams, number of private vehicles.
Passenger number
Total passenger number, passenger number for buses, passenger number for trams, passenger number for private vehicles.
Queue length
Total queue length, queue length for buses, queue length for trams, queue length for private vehicles.
Speed
Average speed, average speed for buses, average speed for trams, average speed for private vehicles.
Current signal phase
One-hot embedding of current signal phase for corresponding intersection.
Table 7: Features to define the state representation
Figure 3: Coverage of the approaching lanes for the example intersection B among a corridor network. Green stands for the vehicle lanes and pink denotes tram lanes. The schematic assumes left-hand traffic.
Figure 4: Phase configurations for action selection.
Figure 5: Partial view of the constructed corridor network in VISSIM for experimental evaluation.
Hyperparameter
Value
Hyperparameter
Value
M - Number of spatial hyperedges
5
Batch size
64
P - Number of temporal hyperedges
6
Actor learning rate
0.0001
K - Number of heads
4
Critic learning rate
0.0003
dmodel - Model dimension
64
Number of episodes
300
Hidden dimension
128
ϵ - Clipping range
0.1
γ - Discount factor
0.99
αentropy - Entropy coefficient
0.001
Table 8: Hyperparameter settings used in the proposed STDSH-MARL model.
Figure 6: Training reward curve over the episodes. The light blue line represents the original cumulative reward, while the dark orange line represents the 10-episode moving average.
Figure 7: Time-series heatmaps of delayed passengers and vehicle queue lengths over the 1,800-s horizon in Scenario 1, comparing all control methods; color intensity indicates magnitude (cooler = lower, warmer = higher).
Model
ANP
AQL
AWT (bus)
AWT (tram)
FS-WF
1401.86
298.88
344.13
112.00
Actuated
1671.05
390.66
350.56
169.75
MP
1385.87
243.63
364.76
581.80
MADQN
1680.78
282.48
944.81
1552.67
MADDQN
1123.50
192.18
687.44
484.40
MAA2C
1679.78
359.62
377.15
321.75
Table 9: Performance comparison for different models (scenario 1)
Figure 8: Time-series heatmaps of delayed passengers and vehicle queue lengths over the 1,800-s horizon in Scenario 2, comparing all control methods; color intensity indicates magnitude (cooler = lower, warmer = higher).
Model
ANP
AQL
AWT (bus)
AWT (tram)
FS-WF
1298.39
286.81
313.97
129.50
Actuated
1542.32
378.17
315.94
172.35
MP
1237.46
255.47
350.10
532.55
MADQN
1501.23
289.10
843.04
1594.54
MADDQN
1031.01
214.91
502.11
640.79
MAA2C
1470.48
325.22
314.49
328.85
Table 10: Performance comparison for different models (scenario 2)
Figure 9: Time-series heatmaps of delayed passengers and vehicle queue lengths over the 1,800-s horizon in Scenario 3, comparing all control methods; color intensity indicates magnitude (cooler = lower, warmer = higher).
Model
ANP
AQL
AWT (bus)
AWT (tram)
FS-WF
1489.44
337.71
354.82
127.20
Actuated
1747.40
387.99
377.09
205.85
MP
1261.59
245.88
284.35
423.85
MADQN
1842.39
302.48
958.39
1594.54
MADDQN
1143.86
195.24
659.35
538.63
MAA2C
1642.75
349.47
362.77
317.50
Table 11: Performance comparison for different models (scenario 3)
Figure 10: Time-series heatmaps of delayed passengers and vehicle queue lengths over the 1,800-s horizon in Scenario 4, comparing all control methods; color intensity indicates magnitude (cooler = lower, warmer = higher).
Model
ANP
AQL
AWT (bus)
AWT (tram)
FS-WF
1452.45
312.61
351.15
124.56
Actuated
1655.16
399.70
354.04
177.85
MP
1267.16
249.59
328.72
377.85
MADQN
1841.18
330.92
769.57
1594.54
MADDQN
1079.67
195.48
559.05
437.10
MAA2C
1649.37
351.65
352.28
336.00
Table 12: Performance comparison for different models (scenario 4)
Figure 11: Time-series heatmaps of delayed passengers and vehicle queue lengths over the 1,800-s horizon in Scenario 5, comparing all control methods; color intensity indicates magnitude (cooler = lower, warmer = higher).
Model
ANP
AQL
AWT (bus)
AWT (tram)
FS-WF
1525.12
323.31
367.67
138.05
Actuated
1632.73
385.13
365.03
166.10
MP
1271.78
241.23
356.08
388.10
MADQN
1567.47
292.65
890.94
1594.54
MADDQN
1165.59
206.80
575.79
656.68
MAA2C
1571.48
363.43
342.23
267.75
Table 13: Performance comparison for different models (scenario 5)
DSHA
SHE
THE
Scenario
ANP
AQL
AWT (bus)
AWT (tram)
✓
✓
×
1
1511.44
324.95
357.38
239.70
✓
✓
×
2
1446.86
334.88
297.68
226.30
✓
✓
×
3
1584.63
347.83
354.56
189.65
✓
✓
×
4
1572.83
355.27
353.03
205.25
✓
✓
×
5
1487.27
335.51
337.15
240.05
✓
✓
×
Average
1520.61
339.69
339.96
220.19
Table 14: Ablation study performance of each component across all scenarios
Comparison
Proposed Mean
Baseline Mean
p -value
STDSH-MARL vs MADQN
791.35
1680.78
0.0
STDSH-MARL vs MADDQN
791.35
1123.50
0.0
STDSH-MARL vs MAA2C
791.35
1679.78
0.0
STDSH-MARL vs MAPPO
791.35
1468.63
0.0
STDSH-MARL vs MP
791.35
1385.87
0.0
STDSH-MARL vs CMRM
791.35
822.11
4.01×10−125
Table 15: Statistical significance testing of number of passengers experiencing delay between the proposed STDSH-MARL and some baseline methods (on Scenario 1).
Figure 12: Training time comparison among different control methods.
Traffic signal control studies how to set intersection phases and green times to reduce congestion while balancing safety, emissions, and priority needs.
Department of Mechanical Engineering, National University of Singapore · Chandra Department of Electrical and Computer Engineering, The University of Texas at Austin · Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology