  In this technical report, we present the 2nd place solution of 2023 Waymo
Open Sim Agents Challenge (WOSAC)[4]. We propose a simple yet effective
autoregressive method for simulating multi-agent behaviors, which is built upon
a well-known multimodal motion forecasting framework called Motion Transformer
(MTR)[5] with postprocessing algorithms applied. Our submission named MTR+++
achieves 0.4697 on the Realism Meta metric in 2023 WOSAC. Besides, a modified
model based on MTR named MTR_E is proposed after the challenge, which has a
better score 0.4911 and is ranked the 3rd on the leaderboard of WOSAC as of
June 25, 2023.
