Observational Assessment of the Effectiveness of Traffic Control Devices on Lane Use Compliance on Motorways

Abstract

Modern roadway design philosophy assumes that slower and non-continuing vehicles remain in the
outside lanes of motorways, which are median-divided, multi-lane, high-speed free-flow roads
characterized by controlled and limited access, e.g., freeways. Correspondingly, proper selection of a
travel lane by the vehicle operator is generally understood to enhance safety and operational performance.
Lane selection according to the basic rule assumes that the innermost (median-adjacent) lane of
the roadway in each direction functions as an auxiliary lane, being reserved for vehicles expediting
passing maneuvers and subsequently vacating the lane. Cultural perspectives indicate a conflict between
those who value the flexibility of passing lane availability and others who demand strict compliance with
the speed limit, constraining the availability of this auxiliary lane. Such inflexible adherence to speed
limits by vehicle automation systems and Intelligent Speed Assistance will further exacerbate the
prevalence of antisocial inappropriate lane use.

This paper presents a model developed to identify the position (leftward, rightward) and status
(expediting, blocking, cruising) of vehicles using the inside lane, based on time-space relationships.
Application of this discrete model to a heuristic field investigation of basic rule conformance and
responsiveness indicated limited local and systemic effectiveness of regulatory signing in the United
States. Cruising and blocking behaviors were observed to be commonplace, suggesting imbalanced
enforcement with respect to speed and a need for additional auxiliary lanes along uphill grades and within
interchanges. Alongside adjustments to policy, enforcement, and education, tactical deployments of
active-feedback signing hold potential for improving conformance with the basic rule.