Can you go 5 over the speed limit in Idaho?

Have you ever been driving down the road, traveling the speed limit along with everyone else, and then suddenly the speed limit drops by 20 miles per hour? Do you wonder, who in the world decided to reduce the speed limit and why? How are speed limits in Idaho set anyway?

Establishing Speed Limits

Speed limits are set by Idaho law, specifically Idaho Code 49-654. In the table below you will see the maximum speed limit for various types of roadways. These limits may be reached where no special hazards or conditions exist that requires a driver to lower their speed to fit conditions, such as weather or condition of the roadway.

However, Idaho’s roadways can be unique from one another. Therefore, an opportunity exists for state and local highway authorities to change the maximum speed limit for roads within their jurisdiction. According to I.C. 49-207, changes to the set maximum speed limit cannot be done arbitrarily, instead they must be accomplished through a traffic engineering study that is managed by a professional engineer licensed in the State of Idaho. If the engineering study finds that adjusting the maximum speed limit is safe and practicable, then the speed limit may be adjusted within the scope of the law.

Here are the maximum speed limits for roads in the Gem State:

Type of Roadway

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It is important to recognize that when a special hazard or condition exists, Idaho Code 49-654 states that vehicle operators shall not “… drive a vehicle at a speed greater than is reasonable and prudent under the conditions and having regard to the actual and potential hazards then existing.” As Brent Jennings, P.E. with Jennings Consulting, LLC explained, this includes approaching and crossing intersections, rail grade crossings, going around curves, approaching hilly terrain, traveling on narrow and winding highways, and when special hazards exist with respect to pedestrians or other types of traffic. This special condition is known as “Basic Rule” and drivers can be cited for violating Basic Rule even though they are driving below the allowed maximum speed limit.

 Did you know?

In Idaho, the speed limit does not have to be posted. However, speed limits are posted to remind motorists of the maximum speed limits.

"It gives motorists flexibility to exceed the posted speed limit on highways where the speed limit is posted at 55 mph or more to safely complete a pass on a slower moving vehicle," said Capt. George Oppedyk of the Jerome County Sheriff's Office.

You can speed up to 15 mph over the posted limit to make your pass, but the Jerome County Sheriff's Office wants you to know there's more to the law than that.

"People just need to be sure they read all the whole law," Oppedyk said.

When you take a look at House Bill 132 you'll notice it has a large paragraph describing the details.

First; you can only be driving a passenger car, motorcycle, or pickup, second; you can't be towing anything when you make the pass, and third; the car you're passing? It has to be going under the posted speed limit.

"It's not a guaranteed 'I won't get a ticket." Oppedyk said.

Law enforcement told me they already give some leeway to cars who are passing, so their enforcement won't change much.

"It may save someone a speeding ticket but for the most part people are already exceeding the speed limit when they pass," Oppedyk said.

The law doesn't apply in adverse weather conditions, or road construction areas, but officers told me, even when the new law does apply, they urge drivers to use caution.

I recently received a question on this subject and thought it was worth a blog post. The driver had been cited for speeding due to driving faster than the posted speed limit while he was passing another vehicle. He explained that he was under the impression that the law "allotted" drivers 15 mph over the speed limit while passing. On a basic level he was correct, however, the circumstances in which you can drive 15 mph over the speed limit are much more complex than people realize.

Idaho Traffic Law

Idaho Code 49-654 subsection (2)(b) explains:

"Subject to all other applicable motor vehicles laws, a driver of a passenger car, motorcycle or pickup truck, not towing any other vehicle, may exceed the posted speed limit by up to fifteen (15) miles per hour while passing another vehicle traveling at less than the posted speed limit, in order to safely pass the vehicle. The overtaking vehicle shall return to the right-hand lane and reduce speed to the posted speed limit as soon as practicable. This paragraph shall be applicable only to passing on the left upon roadways divided into two (2) lanes providing only one (1) lane of traffic in each direction and where the posted speed limit is fifty-five (55) miles per hour or greater. This paragraph shall not be applicable in construction zones."

While this seems straight forward, its not:

1. You must be in a vehicle that is not towing anything
2. You must be on a 2 lane highway; one lane going each direction
3. The posted speed limit must be 55 mph or greater
4. You can not be in a construction zone
5. The vehicle you are passing must be traveling at less than the posted speed limit (if the other vehicle is at or above the posted speed limit this rule does not apply)
6. Driving faster than the posted speed limit must be required in order to safely pass the vehicle (if you can safely pass the other vehicle without exceeding the speed limit then this rule will not apply)
7. You must reduce speed as soon as practicable (most of the time this means immediately; keep in mind that if the other vehicle is traveling under the speed limit there is no risk that they will catch or gain on you when you slow to the posted speed limit)
8. You can only exceed the speed limit if you comply with all other posted laws

There is a lot to unpack here and many people receive citations because they think that you automatically get to exceed the speed limit whenever you pass. Now you know, you don't!

How much over the speed limit can you go to pass in Idaho?

Can you go over 5 mph?

Can you be slightly over the speed limit?

How much over the speed limit can you go?