This course is designed to cover median design from history to actual design. It begins with the benefits and history of median design. Median design terms are defined. Access Management Classification is discussed as it relates to median placement and design.
The different types of median openings are shown from most restrictive to least restrictive. The types of medians are outlined along with the corresponding number of conflict points. The relationship of access vs. through movement is discussed.
Median design issues are outlines as they relate to turn lane development including approach taper, deceleration distance and storage length. Perception-reaction time, design speed and entry speed also play factors in turn lane design.
Definitions of sight distance including negative and positive left turn offsets are defined. A positive offset is preferred because it gives the left turning driver greater visibility of oncoming traffic. There is also a discussion as to how driveways can be strategically placed at median openings to promote safe turning movements.
Properly implemented median management will result in improvement to traffic operations, minimize adverse environmental impacts, and increase highway safety. As traffic flow is improved, delay and vehicle emissions are reduced. In addition, roadway capacity and fuel economy are increased and accidents are less numerous and less severe.
The benefits to medians include:
Safety - Fewer/less severe accidents; less auto/pedestrian conflicts
Efficiency - Higher levels of services; less stop and go traffic
Aesthetics - More room for landscaping and pedestrians; more attractive corridors