  Predicting the movement of other road users is beneficial for improving
automated vehicle (AV) performance. However, the relationship between the time
horizon associated with these predictions and AV performance remains unclear.
Despite the existence of numerous trajectory prediction algorithms, no studies
have been conducted on how varying prediction lengths affect AV safety and
other vehicle performance metrics, resulting in undefined horizon requirements
for prediction methods. Our study addresses this gap by examining the effects
of different prediction horizons on AV performance, focusing on safety,
comfort, and efficiency. Through multiple experiments using a state-of-the-art,
risk-based predictive trajectory planner, we simulated predictions with
horizons up to 20 seconds. Based on our simulations, we propose a framework for
specifying the minimum required and optimal prediction horizons based on
specific AV performance criteria and application needs. Our results indicate
that a horizon of 1.6 seconds is required to prevent collisions with crossing
pedestrians, horizons of 7-8 seconds yield the best efficiency, and horizons up
to 15 seconds improve passenger comfort. We conclude that prediction horizon
requirements are application-dependent, and recommend aiming for a prediction
horizon of 11.8 seconds as a general guideline for applications involving
crossing pedestrians.
