office of traffic, safety, and operations warning signs freeway signing plan design april 29, 2008

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Warning SignsWarning Signs

Freeway Signing Plan DesignApril 29, 2008

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Function of Warning SignsFunction of Warning Signs

– Call attention to unexpected conditions or situations not readily apparent to road users

– Alert road users to conditions that might call for a reduction in speed or an action in the interest of safe and efficient operation

2C.12C.1

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Placement of Warning SignsPlacement of Warning Signs

– The time needed to complete a reaction to a sign is the sum of time for:• Perception• Identification (understanding)• Emotion (decision-making)• Volition (execution)

– Table 2C-4 (TEM Chart 6.5) lists suggested sign placement

2C.52C.5

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MN MUTCD Table 2C-4 TEM Chart 6.5

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– Distances in Table 2C-4 are for guidance and should be applied with engineering judgment

– Signs should not be placed too far in advance of the condition, such that drivers will forget, especially in urban areas

2C.52C.5

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Advance Traffic Control Advance Traffic Control SignsSigns

– The Stop Ahead and the Yield Ahead signs shall be installed on an approach to a primary traffic control device that is not visible for a sufficient distance to permit the road user to respond to the device.

2C.292C.29

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– The Signal Ahead sign shall be installed on an approach to a traffic control signal which does not meet the visibility criteria for a traffic control signal as specified in Table 4D-1.

2C.292C.29

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– An Advance Traffic Control sign may be used for additional emphasis of the primary traffic control device, even when the visibility distance to the device is satisfactory.

2C.292C.29

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Ramp Meter Ahead SignRamp Meter Ahead Sign

– The RAMP METER AHEAD (W3-X1) sign may be used on a freeway entrance ramp having a ramp control signal which is not visible for a sufficient distance to allow a motorist adequate time to bring his vehicle to a stop at the signal.

2C.29.12C.29.1

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Speed Reduction SignSpeed Reduction Sign

– 48” x 48”– Shall be used if the reduction in speed limit

between zones is 15 mph or greater• For difference in zones of 10 mph or less, use

engineering judgment

– Shall be installed 1000’ in advance of first speed limit sign

• May be installed up to 1700’ in advance due to geometrics, grade, or sign clutter

– A two-line distance plaque may be used – In-place speed reduction signs shall be

replaced through attrition

6-6.166-6.16

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Advisory Exit Speed SignAdvisory Exit Speed Sign6-6.04 / 2C.366-6.04 / 2C.36

– Shall be installed if the maximum recommended speed on a ramp, as it exits the mainline roadway, is 70% or less of the design speed of the mainline roadway.

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Advisory Exit Speed SignAdvisory Exit Speed Sign2C.362C.36

– The Exit Speed sign should be used along the deceleration lane.

– The Exit Speed sign should be visible in time for the road user to make a safe slowing and exiting maneuver.

– The Ramp Speed sign should be visible in time for the road user to reduce to the recommended speed.

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– One or more Ramp Speed signs may be used beyond the gore and along the ramp where the recommended speed changes because of a change in curvature or when there is a need to remind road users of the recommended speed.

– Based on engineering judgment, the Ramp Speed sign may be installed on the inside or outside of the curve to enhance its visibility.

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– A Curve Speed sign may be used at and beyond the beginning of a curve following a Horizontal Alignment and Advisory Speed sign combination.

• To remind road users of the recommended speed• Where the recommended speed changes because

of a change in curvature

office of traffic, safety, and operations warning signs freeway signing plan design april 29, 2008

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