Safe speed and stopping distance

Key points

1. Never drive faster than is reasonable and prudent for the conditions at the time.

   Source: Handbook p. 16

   “Kansas' basic speed law requires that you never drive a vehicle at a speed greater than is reasonable and prudent under the conditions then existing.”
   Kansas Driving Handbook, Handbook p. 16

2. Even without a posted minimum speed, it is unlawful to drive so slowly that you block normal traffic.

   Source: Handbook p. 16

   “Even when a minimum speed is not posted, it is unlawful to drive a vehicle so slowly as to impede or block the normal movement of traffic.”
   Kansas Driving Handbook, Handbook p. 16

3. At 50 mph, the average driver travels 55 feet during reaction time, before braking starts.

   Source: Handbook p. 58

   “The average driver has a reaction time of ¾ second to 1 second. At 50 mph this accounts for 55 feet traveled.”
   Kansas Driving Handbook, Handbook p. 58

4. At 50 mph on dry pavement with good brakes, braking alone takes about 158 feet.

   Source: Handbook p. 58

   “At 50 mph on dry pavement with good brakes, it can take about 158 feet.”
   Kansas Driving Handbook, Handbook p. 58

5. Total stopping distance at 50 mph is at least 268 feet.

   Source: Handbook p. 58

   “At 50 mph, your vehicle will travel a minimum of 268 feet.”
   Kansas Driving Handbook, Handbook p. 58

6. Doubling speed from 20 to 40 mph makes impact 4 times greater and braking distance 4 times longer.

   Source: Handbook p. 59

   “When you double your speed from 20 to 40 mph the impact is 4 times greater. The braking distance is also 4 times longer.”
   Kansas Driving Handbook, Handbook p. 59

7. At 60 mph, if you cannot see at least 400 feet ahead, you are going too fast for your visibility.

   Source: Handbook p. 57

   “At 60 mph if you cannot see at least 400 feet ahead, you are driving too fast for your visibility.”
   Kansas Driving Handbook, Handbook p. 57

8. Driving more than 15 mph slower than traffic can be as dangerous as speeding.

   Source: Handbook p. 60

   “Driving more than 15 mph slower than the traffic flow pattern can be just as dangerous as excessive speed.”
   Kansas Driving Handbook, Handbook p. 60

9. The best way to avoid speeding is to check your speedometer often.

   Source: Handbook p. 62

   “The best way to avoid speeding is to check your speedometer frequently.”
   Kansas Driving Handbook, Handbook p. 62

Numbers to know

3 questions from the Kansas practice test

1. 1. What does Kansas basic speed law require when road, weather, or vehicle conditions change?

   1. Always drive exactly at the posted limit
   2. Never drive faster than is reasonable and prudent under the conditions
   3. Drive 10 mph below the limit in every rainstorm
   4. Match the fastest nearby vehicle
   Show answer

   Never drive faster than is reasonable and prudent under the conditions. Kansas basic speed law requires a driver to stay at or below a speed that is reasonable and prudent under the conditions then existing. The assessment includes the road, weather, vehicle, and the driver's physical condition. A posted limit is not a command to maintain that speed when conditions make it unsafe. The fixed 10 mph reduction is not the handbook's formula, and matching the fastest vehicle substitutes another driver's choice for a safety judgment. Before selecting a speed, scan for hazards and adjust to what the conditions actually allow.

2. 2. When can driving below an unposted minimum speed become unlawful in Kansas?

   1. Only when the driver is in the left lane
   2. Whenever the vehicle travels below 25 mph
   3. When the slow driving impedes or blocks normal traffic, unless needed for safe operation
   4. Never, because only speeding is regulated
   Show answer

   When the slow driving impedes or blocks normal traffic, unless needed for safe operation. Kansas makes it unlawful to drive so slowly that the vehicle impedes or blocks the normal movement of traffic, even when no minimum speed sign is posted. There is an exception when the slower pace is necessary for safe operation under the basic speed law. The 25 mph number is invented, and the rule is not limited to a left lane. The never choice ignores the handbook's explicit minimum-speed provision. Use a concrete check: if traffic is stacking behind you, consider whether a hazard requires the slower speed and whether you can safely allow traffic to pass.

3. 3. When a Kansas road has a posted speed limit different from the statutory maximum, which limit must you follow?

   1. The posted limit
   2. The higher statutory maximum
   3. The average speed of surrounding traffic
   4. The limit selected by the driver before entering the road
   Show answer

   The posted limit. Kansas lists its statutory maximum speeds as applying unless otherwise posted. A posted limit therefore controls when it differs from the general maximum for that road type. Choosing the higher number defeats the purpose of the sign, and surrounding traffic cannot authorize a faster speed. Before relying on a familiar default, scan for the sign and also adjust below that limit when road, weather, traffic, vehicle, or personal conditions make the posted speed unsafe.

Source: the Kansas Driving Handbook, Section 7: Safe Driving Tips. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.