The link transmission model (LTM) is an efficient and widely used macro-level
approach for simulating traffic flow. However, the state-of-the-art LTMs
usually focused on segment-level modelling, in which the traffic operation
differences among multiple turning directions are neglected. Such models are
incapable of differentiating the turn-level queue transmission, resulting in
underrepresented queue spillbacks and misidentification of bottlenecks.
Moreover, a constant free-flow speed is usually assumed to formulate LTMs,
restricting their applications to model dynamic traffic management strategies
involving variable speed limits (VSL) and connected and automated vehicles.
This study proposed an extended LTM with VSL and turn-level queue transmission
to capture the traffic flow propagation at signalized intersections. First,
each road segment (RS) with multiple turning directions is divided into many
free-flow and queueing parts characterized by the triangular fundamental
diagrams. Then, the vehicle propagation within the link is described by the
turn-level link inflow, queue inflow, and outflow, which depends on the
free-flow speed changes. A node model involving an iterative procedure is
further defined to capture the potential queue spillback, which estimates the
actual flow propagation between the adjacent RSs. Simulated and field data were
used to verify the proposed model performance. Results reveal that the proposed
LTM predict traffic operations of complex intersections with multiple turning
movements, VSL and signal control schemes, and enables an accurate yet
computationally tractable representation of flow propagation