Regulatory Road Sign (R2-4)
Minimum Speed Limit Sign Meaning & Driving Rules
Prohibits driving slower than the posted minimum speed (e.g. 45 mph) on high-speed freeways in good weather.
Required Driver Action & Right-of-Way Protocol
Maintain a speed between the posted minimum and maximum limits. Use hazard lights if forced to travel slower due to vehicle malfunction.
Detailed Overview & Purpose
The Minimum Speed Limit sign (R2-4) prevents slow-moving vehicles from impeding the flow of traffic on high-speed expressways. Driving excessively slowly creates dangerous speed differentials that trigger rear-end collisions.
If your vehicle cannot maintain the minimum speed, you must exit the freeway and use secondary roads.
Key Standard & Origin: Speed differentials (differences in speed between vehicles) cause more highway collisions than absolute high speed.
Where You'll Find This Sign
Interstate highways, rural turnpikes, and high-speed tollways.
Common Driver Mistakes to Avoid
Driving 30 mph in clear weather on an interstate with a 45 mph minimum speed limit.
How This Sign Appears on the DMV Knowledge & Road Test
Tests traffic flow impedance rules on high-speed controlled-access highways.
Legal Penalties and Moving Violations
Impeding the normal flow of traffic carries moving violation fines.
When you encounter the official Minimum Speed Limit (R2-4) on a roadway, what is your legal duty?
Prepare for Your State Permit Exam
Take full 2026 practice tests covering mandatory road signs, traffic laws, and state-specific driving rules.
