  In urban streets, the intrusion of pedestrians presents significant safety
challenges. Modelling mixed pedestrian-vehicle traffic is complex due to the
distinct motion characteristics and spatial dimensions of pedestrians and
vehicles, making unified modelling difficult, with few studies addressing these
issues. This paper employs a multi-grid cellular automata model to bridge the
gap between vehicle and pedestrian models. An Improved Kerner-Klenov-Wolf
(IKKW) model and a pedestrian motion model that incorporates Time-To-Collision
(TTC) are introduced. Both models update the spatial motions of vehicles and
pedestrians uniformly. Empirical analysis indicates that the model achieves
high simulation accuracy. This model effectively illustrates the impact of
pedestrian intrusion within mixed traffic scenario. The fundamental diagram of
heterogeneous traffic reveals substantial differences, highlighting the effects
of pedestrian intrusion on traffic flow states and identifying six phase
regions in mixed traffic. Additionally, this paper examines conflicts between
pedestrians and vehicles under varying speed limits and sidewalk widths,
demonstrating that lower speeds and broader sidewalks significantly reduce the
frequency of pedestrian-vehicle conflicts. Notably, the frequency of peak
conflicts at a vehicle speed limit of 60.48 km/h is more than three times
higher than at 30.24 km/h. This model offers a potential approach to studying
mixed traffic flows and exhibits substantial scalability.
