4.0 Geometric and Safety Design

4.3.3 Recommended Guidelines

Express ETC Lane Design Issues

Some of the significant issues to consider in establishing express lanes include the following:

potential solution for alleviating speed differentials in the conventional plaza that includes ETC dedicated lanes and cash lanes,
location of the express lanes under both the initial and ultimate builds,
minimizing abrupt lane changes at the tolling point and license plate image capture zone,
safe and operationally efficient divergence of traffic into the express lanes and conventional plaza lane when approaching a plaza,
safe and operationally efficient merger of express lanes and conventional plaza traffic downstream of the toll plaza,
provisions for maintaining existing reversible lane operations in the conventional plaza after verifying the need to continue the operation of these lanes,
maintaining the existing location of the administration building and parking within the roadway median,
weave length from upstream on-ramp gore to express lane - conventional plaza approach gore,
weave length from express lane - conventional plaza departure gore to downstream off-ramp gore,
allocation of available right-of-way to the express lanes, conventional plaza lanes, administration building(s) and any plaza bypass lanes.

Express ETC Lanes Guidelines

Guideline	Express Lane Design Guideline 1
Title	Lane Placement
Text	To avoid or minimize potential conflicts, express lanes should be located to the far left of the plaza.
Commentary	This is consistent with general highway travel, therefore, meets the expectations of the drivers. This affectively prohibits any reversible lane operation. Facilities where staff must access tollbooths or toll equipment from a facility located in the median, a tunnel or overhead walkway is needed to accommodate express lanes located to the far left. See Chapter 2 for more information on toll plaza configuration.

Guideline	Express Lane Design Guideline 2
Title	Express Lane Design
Text	Design of express lanes should preferably be a continuation of the normal mainline lanes with similar features (i.e. design speed, lane widths, and shoulder widths). The split between the express lanes and the conventional plaza lanes should occur prior to approach transition zone for the adjacent conventional plaza, and the merge downstream of the toll plaza should occur after the departure transition zone. (see glossary of terms and definitions for description of zones)
Commentary	A barrier wall, guardrail, delineators and/or other types of physical separation should be considered between the express lanes and the conventional toll plaza lanes when highway standard clear zone separation is available to prevent confused and deviant drivers from trying to access the conventional plaza.

Guideline	Express Lane Design Guideline 3
Title	Diverging and Merging Express Lane and Conventional Plaza Lane Traffic
Text	Design of the conventional plaza approach and departure zones from and to the roadway mainline should comply with diamond interchange standards, with the express lanes functioning as the mainline through lanes.
Commentary	The design must account for the available right-of-way and the ultimate number of express and conventional plaza lanes, shoulder widths, and median. The ultimate express lane width should be equal to the ultimate mainline cross section.

Federal Highway Administration - United States Department of Transportation