Express Lane Design Issues and Guideline Development
When a toll road operator cannot meet the AASHTO Green Book freeway lane guidelines at a site due to geometric constraints such as immovable features or interchanges closer than one mile, the design should consider dedicated lanes for the conventional plaza, subject to accommodating design provisions for future conversion to ORT. The AASHTO Green Book is predominately adopted by toll agencies and DOTs, either directly or through incorporation into their design standards, for mainline roadway design.
Express Lane Guidelines
Guideline | ETC Express Lane Guideline 1 |
Title | ETC Express Lane Count |
Text | New express lane plaza design and construction should include the number of express lanes equal to the number of approach roadway lanes, including provisions for widening if the approach roadway is configured for future widening. |
Commentary | This provision assures that a given toll plaza will never require future modifications or lane conversions to meet customer demand for non-stop lanes. This design guideline is important for several reasons: 1) The appearance of a wide-open path “through the plaza” is a very effective marketing tool 2) Once constructed, future changes are not required to accommodate higher ETC demand at the toll facilities, assuming the mainline is not widened. This eliminates additional express lane design and construction along with the risk of reduced revenue resulting from delays caused by reconstruction. This guideline applies to full express lane plazas in new construction or re-construction. |
Guideline | ETC Express Lane Guideline 2 |
Title | ETC Express Lane Orientation |
Text | Express lanes should be oriented to the left, as a continuation of the mainline approach pavement. |
Commentary | Express Lanes should appear to the driver as a simple continuation of the mainline through the tolling zone or point, not requiring any change in driving pattern. |
Guideline | ETC Express Lane Guideline 3 |
Title | ETC Express Lane Separation of Traffic |
Text | Express lanes should be protected and separated from conventional plaza traffic according to the expressway design criteria applied on the approach and departure roadways. |
Commentary | Express Lanes should appear to the driver as a simple continuation of the mainline lanes, not requiring any change in driving pattern. |
Guideline | ETC Express Lane Guideline 4 |
Title | ETC Express Lane Utilization Restrictions |
Text | Express lanes should not restrict usage by particular vehicle types, such as “cars only,” or “trucks only,” beyond those restrictions in force on the approach and departure roadway or the roadway facility in general. |
Commentary | Express Lanes should appear to the driver as a simple continuation of the toll facility, not requiring any change in driving pattern. An exception is a single lane express lane, which should prohibit truck usage because the operational performance of trucks tends to cause delays and safety concerns when mixed in the same lane with passenger cars |
Guideline | ETC Express Lane Guideline 5 |
Title | ETC Express Lane Roadway Geometry |
Text | Express lanes should be designed meeting the same geometric requirements for grades, cross-slopes, clearances and clear zones, stopping sight distance and horizontal and vertical curvature, as is applied to the proximate approach and departure roadways. |
Commentary | Express Lanes should appear to the driver as a simple continuation of the toll facility, not requiring any change in driving pattern. |
Guideline | ETC Express Lane Guideline 6 |
Title | ETC Express Lane Posted Speeds |
Text | Express lane posted speed should not deviate from the posted speed on the interconnecting mainline. |
Commentary | Express Lanes should appear to the driver as a simple continuation of the mainline, not requiring any change in driving pattern. |
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