The presence or absence of a median has a substantial impact on roadway operations and safety.  Medians can be categorized into the following:

Non-traversable median:  a physical barrier in the roadway that separates traffic traveling in the opposite directions, such as a concrete barrier or a landscaped island.  These are recommended for all new or reconstructed multi-lane highways.  Additional details are included in the Kentucky Median Type Guidance.

Continuous two-way left-turn lane (TWLTL):  a continuous lane located between opposing traffic streams that provides a refuge area for vehicles to complete left turns from both directions.  A TWLTL is only recommended in limited applications.