This provision almost assures that a given toll plaza will no longer require future modifications or lane conversions to meet customer demand for non-stop lanes. In theory, it could be appropriate to not provide dedicated lanes for new toll plaza construction, and instead rely on mixed-use lanes until ETC participation increases to levels required to fully use dedicated lanes. In practice, all major new toll roads rely heavily on non-stop ETC to be publicly acceptable. This is because the provision of non-stop toll collection is typically a requirement to “sell” the project to the public.

Exceptions may be warranted when interchange ramps are in the approach or departure zones, or high volumes of commercial traffic are present. In these conditions, a supplemental dedicated lane towards the right of the plaza, to support traffic entering or exiting the system, or to isolate ETC commercial vehicles from the large volumes of commuter traffic in the left dedicated lanes, may be warranted.

The conversion of cash toll collection lanes into dedicated lanes at ramp plazas has been challenging, particularly for ticket system operators which have plazas located close to at least two merges and splits in trumpet interchanges. Dedicated lane selection must be made based on traffic characteristics of the individual toll operator. The New York Thruway, for example, often uses center lanes in these plazas for dedicated lanes, as this allows a single dedicated lane to serve traffic departing the plaza area to the left or the right without weaving.

As ETC participation climbs above 50%, the need for reversible toll lanes lessens in most locations other than those with reversible mainline lanes. Permanent barrier is expected to assist the driver in navigating the plaza. Also, the task of moving cones to shift plaza centerlines is a dangerous field assignment, and with increasing driver speeds is becoming more dangerous. Notwithstanding the use of rigidly followed safety procedures when visibility is good, this practice should be discontinued as soon as it is feasible.

For major bridge and tunnel crossings, where significant reversible lane or contra-flow traffic operations are used, the use of moveable concrete barrier could be considered if the expense is warranted. When available, a clear zone between opposing traffic directions provides an open area (i.e., no obstacles present) considered sufficient for a driver to regain control of the vehicle and avoid a collision.

Retrofits of existing plazas may deviate from these guidelines, but the designer needs to consider expected operating speed and protection of adjacent obstacles.

For new or reconstructed facilities, island width should be dictated by the more controlling toll booth width plus lane clearance or lane clearance plus safe access to toll island equipment.

Maximum-posted speeds lower than 25 mph may apply for ramp plazas located within trumpet interchanges.