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4.0 Geometric and Safety Design

4.3 Express Lanes

There are many real and potential safety concerns at toll plazas, with particular regard to multiple payment methods that include ETC technology. Inclusion of this technology at toll plazas introduces another option for users that may add to their confusion on lane choice. ETC technology eliminates the need for drivers to stop for toll payment. As such, it creates speed differentials in the overall flow of traffic. In an effort to minimize conflicts and adverse conditions associated with these speed differentials, the higher speed ETC lanes are physically separated from the conventional plaza lanes where cash payment requires the vehicle to stop.

The ETC dedicated lane is a lane within a conventional plaza that is only equipped to collect tolls electronically, thereby limiting use of the lane to vehicles having a valid transponder. Dedicated lanes usually do not require the driver to stop their vehicle, however, due to physical constraints, collection staff safety, and speed differential concerns, the allowable travel speed is usually much less than the posted speed limit on the approach to the toll plaza. Express lanes are effectively equivalent in design to the approach and departure roadway sections. The exceptions are the number of express lanes are typically less than the approach roadway lanes and barrier is installed to prevent access to the express lanes from the conventional plaza along with guiding vehicles away from the overhead structure supporting toll equipment. Express lanes are capable of supporting a much higher throughput of traffic and result is the least amount of delay relative to all plaza lane types. Because a single express lane prevents a user from passing a slower moving vehicle and requires wide shoulders to assure continued vehicle passage if lane blockage occurs, two express lanes are often considered a practical minimum.

To minimize conflicts, locating express lanes to the far left of a directional toll plaza is generally recommended, since faster drivers typically stay to the left and the approach roadway alignment is easier to maintain through the express lanes, assuming sufficient right of way is available to the far right. To separate high speed, non-stop vehicles from the conventional plaza that supports both lower speed ETC dedicated lanes and cash lanes, a barrier, a raised median providing an adequate clear zone, or a combination of barrier (e.g., hazard protection) and clear zone is normally used commensurate with the speed of the approach roadway. This configuration also discourages drivers from making lane changes close to the toll plaza.

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