The project survey results of cross slopes for express lanes had a range of 1.5%-3.0%, with 2% the most common.
Adequate cross slopes need to be constructed to facilitate proper pavement drainage. Providing adequate drainage is critical in the vicinity of the toll plaza, particularly during periods of low temperatures that promote the formation of ice. Express lanes should adhere to the guidelines used for the mainline highway segment.
The AASHTO Roadside Design Guide 2002 states that grades (profile or cross slopes) should be avoided near crash cushions, as these features can adversely affect the errant vehicle impact angle and possibly the collapse mechanism of the impact attenuator under load. Mainline plazas constructed on roadway curve sections present special challenges in meeting this criteria because of provisions for superelevation.
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