12.6 Driver Expectations at Freeway Lane Drops and Lane Reductions

Because lane drops can confuse motorist, increase variability in speed, and result in erratic driving behaviors, designs need to match motorist expectations. Table 12.2 lists design practices that foster safe driving.

Table 12.2 Design Guidance for Lane Drops and Lane Reductions
Principle	Guideline
Provide Continuous Visibility	The minimum distance visible to the motorist should be enough for them to: Perceive a lane is ending Evaluate maneuver options Transition to an adjacent lane
Minimize Attention-Dividing Conditions	Situate lane drops away from ramps or complex signs.
Provide Adequate Transition Cues	Tapers should be long enough so motorists who are unaware of the lane drop have enough time to maneuver.
Coordinate the Visual and Operational Drop	Establish a lane reduction so the lane does not appear to continue past the operational reduction.
Provide an Adequate Escape Area	Designate an escape area at exit lane drops to accommodate drivers who do not have enough time before the exit core to make a normal lane change.
Notify Drivers That a Lane Is Not Continuous	Warn drivers that an add-drop lane does not continue.
Install Adequate Traffic Control Devices	Install traffic control devices that communicate to motorists: The lane drop’s presence and location Instructions for navigating the lane drop

Do not place lane drops where motorists confront visual complexity and are thus distracted by looking at other road features (e.g., just over a crest vertical curve, just downstream of a horizontal curve).
If a lane drop has option lanes, communicate to the motorist:
- The dropped lane only reaches the exit
- The option lane leads to either the exit destination or mainline
- Any other lane only reaches the mainline
- Identifying information for each destination (e.g., street name, destination name)

Do you have more questions? Get in touch!



Chris VanDyke

Research Scientist | Program Manager

chrisvandyke@uky.edu