Minimum speed limits

[SkyPesos]

From what I know of, Ohio currently doesn't post minimum speeds. When I moved to the state, they had speed limit signs with the speed limit on the top half, and something whited-out on the bottom half. I had no clue what is under there, but my guess is that it's the minimum speed. The state eventually replaced all of them with the standard speed limit sign.

In Missouri, specifically the St. Louis area, all the freeways I've been on have a minimum speed of 40. Not sure if the state is still posting that or not.

On some freeways in China, there's a minimum speed for each lane. Normally, the right lane has the lowest minimum, the center lane(s) has one slightly higher than the right lane, and the left lane has the most restrictive minimum, along with a raised maximum. It's signed with a blue circle. Example

[1995hoo]

From what I know of, Ohio currently doesn't post minimum speeds. When I moved to the state, they had speed limit signs with the speed limit on the top half, and something whited-out on the bottom half. I had no clue what is under there, but my guess is that it's the minimum speed. The state eventually replaced all of them with the standard speed limit sign.

In Missouri, specifically the St. Louis area, all the freeways I've been on have a minimum speed of 40. Not sure if the state is still posting that or not.

On some freeways in China, there's a minimum speed for each lane. Normally, the right lane has the lowest minimum, the center lane(s) has one slightly higher than the right lane, and the left lane has the most restrictive minimum, along with a raised maximum. It's signed with a blue circle. Example

That link doesn't work, but I recall that the first time I travelled through Ohio on a family trip to Michigan and Ontario in 1987, Ohio's speed limit signs were a larger rectangular shape with a 65-mph speed limit for cars and a lower speed limit for some other vehicles identified in a load of small print. Maybe that's what's whited-out on the sign you mention? Split speed limits for trucks, and sometimes buses, weren't all that unusual around that time period as some state legislatures were panicky about allowing 65-mph speed limits. For example, I recall starting in 1988 Virginia allowed 65 for cars and 55 for trucks and buses, then changed the latter just to trucks, then later removed it altogether.

Edited to add: I found this example via a Google search.

[PurdueBill]

From what I know of, Ohio currently doesn't post minimum speeds. When I moved to the state, they had speed limit signs with the speed limit on the top half, and something whited-out on the bottom half. I had no clue what is under there, but my guess is that it's the minimum speed. The state eventually replaced all of them with the standard speed limit sign.

In Missouri, specifically the St. Louis area, all the freeways I've been on have a minimum speed of 40. Not sure if the state is still posting that or not.

On some freeways in China, there's a minimum speed for each lane. Normally, the right lane has the lowest minimum, the center lane(s) has one slightly higher than the right lane, and the left lane has the most restrictive minimum, along with a raised maximum. It's signed with a blue circle. Example

That link doesn't work, but I recall that the first time I travelled through Ohio on a family trip to Michigan and Ontario in 1987, Ohio's speed limit signs were a larger rectangular shape with a 65-mph speed limit for cars and a lower speed limit for some other vehicles identified in a load of small print. Maybe that's what's whited-out on the sign you mention? Split speed limits for trucks, and sometimes buses, weren't all that unusual around that time period as some state legislatures were panicky about allowing 65-mph speed limits. For example, I recall starting in 1988 Virginia allowed 65 for cars and 55 for trucks and buses, then changed the latter just to trucks, then later removed it altogether.

Edited to add: I found this example via a Google search.

That is most likely a split limit sign with truck limit covered; most have been changed out but some remain still.  This is what they used to look like in the conventional form:
https://goo.gl/maps/rkcBoN2XwiV5tJee9
There was also the "menu" format Big White Sign as pictured above and sometimes they would use two separate signs, one regular and one right next to it with the truck limit.

Minimum signs are seen in Ohio, often unattended by a maximum limit sign.
Cleveland:  https://goo.gl/maps/4XaKtwJSBp1NyFA2A 
Akron:  https://goo.gl/maps/CNoitkijzvRhJfct9 

Combo max/min signs used to be seen in CLE, but seem to have disappeared a while ago.
https://goo.gl/maps/amXdcmev3sysvgZP8
https://goo.gl/maps/wYRbYHgBM77MsqPy6
Otherwise, a tall sign with SPEED LIMIT on top like the one whited out was almost always the split car/truck limit sign.

The Ohio Turnpike got the OK to remove the split car/truck limit first, as truckers were shunpiking on parallel roads because they were limited to lower speeds on the Turnpike that could be matched on the other roads.  ODOT and other roads were OKd later.

Edit: Older street view of the Loveland sign (not the easiest to get) shows that it was indeed a split 65/55 sign.
https://goo.gl/maps/31t9uentQ5mvCsdx8

This sign on I-90 is a good example of a sign with the split truck limit (2013) then covered up (2014).
https://goo.gl/maps/csFvujRoXRQp2wQb6

[US 89]

Utah uses them, but sometimes with a "when conditions permit" banner

Is this the case anymore? The only one I knew of was on I-15 in northern Salt Lake City (with a "when conditions reset" banner), and it was removed when that portion was reconstructed in 2009. I can't think of any others off the top of my head.

Apparently signage for the 45 mph interstate minimum speed was far more common in the early days of the freeway system.

[doorknob60]

Utah uses them, but sometimes with a "when conditions permit" banner

Is this the case anymore? The only one I knew of was on I-15 in northern Salt Lake City (with a "when conditions reset" banner), and it was removed when that portion was reconstructed in 2009. I can't think of any others off the top of my head.

Apparently signage for the 45 mph interstate minimum speed was far more common in the early days of the freeway system.

My guess is not, or at least not on I-15. I never visited Utah until 2015, and I've now been a few times, including the full length of I-15 in the state. I don't think I've ever seen any minimum speed limit signed.

[kphoger]

my guess is that the 40mph minimum (and similar minimums in neighboring states with lower maximums) is mainly to help keep farm equipment off the Interstates.

Also, don't use this highway if half your cylinders aren't firing.

[StogieGuy7]

Utah uses them, but sometimes with a "when conditions permit" banner

Is this the case anymore? The only one I knew of was on I-15 in northern Salt Lake City (with a "when conditions reset" banner), and it was removed when that portion was reconstructed in 2009. I can't think of any others off the top of my head.

Apparently signage for the 45 mph interstate minimum speed was far more common in the early days of the freeway system.

They were everywhere on Utah freeways - back in the 1980s.

[roadman65]

Florida depends on the FDOT district. D5 removed the 40 mph minimum as well as FTE for Florida's Turnpike. D7 also removed most of them. D1 and D3 uses them still. Districts 2, 4, and 6 do not know.

Florida had them all over before the mid 90's though.

[sprjus4]

TX-49 near Tyler, TX, an undivided 2-3 lane (alternating passing lane) toll road, has a minimum speed limit of 65 mph. The maximum speed limit is 75 mph.

https://www.google.com/maps/@32.2549529,-95.4006534,3a,47.9y,329.11h,81.04t/data=!3m6!1e1!3m4!1sZHbiVSvZWKYdMnwUFYhwxw!2e0!7i13312!8i6656!5m1!1e1

[NoGoodNamesAvailable]

TX-49 near Tyler, TX, an undivided 2-3 lane (alternating passing lane) toll road, has a minimum speed limit of 65 mph. The maximum speed limit is 75 mph.

https://www.google.com/maps/@32.2549529,-95.4006534,3a,47.9y,329.11h,81.04t/data=!3m6!1e1!3m4!1sZHbiVSvZWKYdMnwUFYhwxw!2e0!7i13312!8i6656!5m1!1e1

Wow, only in Texas. But a 65 minimum is totally ridiculous.

[MikeTheActuary]

Wow, only in Texas. But a 65 minimum is totally ridiculous.

In abstract....if minimum speed limits exist to promote safety and traffic flow by reducing the disruption caused by speed differentials, then on a highway with a 75mph speed limit, wouldn't it make more sense to have a minimum speed that is only 10mph lower, rather than a minimum speed that is 30mph lower?

Back in the days of the mandatory 55mph speed limits, signing freeway as "Speed limit 55 / minimum 45" (which I remember being common in the states I most frequently was in growing up) made a certain amount of sense to me.  If you couldn't come close to highway speed, you needed to stay off the highway for safety, and 10mph seemed like a not unreasonable difference.   But in states that used to frequently post 45mph minimums...those minimums were mostly retained when 55 became 65 or more.

If you're going to tolerate traffic going 60% of the posted maximum speed, then it makes sense to me to quit bothering to have a posted minimum, especially given questions raised about conditions that require lower speeds.  But if you are trying to reduce speed differentials for safety and traffic flow, then a minimum of 65 on a 75mph highway makes sense.

[SectorZ]

my guess is that the 40mph minimum (and similar minimums in neighboring states with lower maximums) is mainly to help keep farm equipment off the Interstates.

Also, don't use this highway if half your cylinders aren't firing.

That's a standard highway-speed feature for Honda's V6 engines.

[1995hoo]

my guess is that the 40mph minimum (and similar minimums in neighboring states with lower maximums) is mainly to help keep farm equipment off the Interstates.

Also, don't use this highway if half your cylinders aren't firing.

That's a standard highway-speed feature for Honda's V6 engines.

Nor is it a problem, either.

[kphoger]

Hmm.  Well.

I just remember when one bank of my old 2004 V6 Grand Caravan's coil stopped receiving information from the PCM to fire its two cylinders.  Running on just four out of six for a couple of weeks, I didn't feel comfortable going much over 50 mph.  Drove on the Canal Route here with my flashers on quite a bit.

[vdeane]

Wow, only in Texas. But a 65 minimum is totally ridiculous.

In abstract....if minimum speed limits exist to promote safety and traffic flow by reducing the disruption caused by speed differentials, then on a highway with a 75mph speed limit, wouldn't it make more sense to have a minimum speed that is only 10mph lower, rather than a minimum speed that is 30mph lower?

Back in the days of the mandatory 55mph speed limits, signing freeway as "Speed limit 55 / minimum 45" (which I remember being common in the states I most frequently was in growing up) made a certain amount of sense to me.  If you couldn't come close to highway speed, you needed to stay off the highway for safety, and 10mph seemed like a not unreasonable difference.   But in states that used to frequently post 45mph minimums...those minimums were mostly retained when 55 became 65 or more.

If you're going to tolerate traffic going 60% of the posted maximum speed, then it makes sense to me to quit bothering to have a posted minimum, especially given questions raised about conditions that require lower speeds.  But if you are trying to reduce speed differentials for safety and traffic flow, then a minimum of 65 on a 75mph highway makes sense.

Yeah, I always wonder what happens with minimum speed limits in congestion or bad weather.  Does that mean everyone is breaking the law in those instances?

[Richard3]

I figure out that minimum speed limits are made to keep vehicles into a "speed bracket", in order to avoid a too big difference between slower and faster vehicles.  Because the real danger is not the speed itself (some vehicles are safe over 100 MPH!), but the speed difference between vehicles.

By experience, I generally see a difference of 25 MPH (40 km/h) in many states that show minimum speed limits.  As a truck driver, when I have to climb hills, I put 4-way flashers when I have to go under the minimum speed, and if no minimum speed shown, at about 25 MPH under the maximum speed limit.

[kphoger]

the real danger is not the speed itself (some vehicles are safe over 100 MPH!), but the speed difference between vehicles.

The vehicle may be safe over 100 mph, but that doesn't mean the driver is.

[Scott5114]

Yeah, I always wonder what happens with minimum speed limits in congestion or bad weather.  Does that mean everyone is breaking the law in those instances?

It's possible that it does, technically. But only a pinhead police chief would order their troopers to issue tickets in that instance.

More likely is that the law is structured so that the "too fast for conditions" clauses override the minimum speed clauses. If "too fast for conditions" is 35 MPH, and the minimum is 45, then the minimum gets ignored.

[kphoger]

Yeah, I always wonder what happens with minimum speed limits in congestion or bad weather.  Does that mean everyone is breaking the law in those instances?

It's possible that it does, technically. But only a pinhead police chief would order their troopers to issue tickets in that instance.

More likely is that the law is structured so that the "too fast for conditions" clauses override the minimum speed clauses. If "too fast for conditions" is 35 MPH, and the minimum is 45, then the minimum gets ignored.

Indeed.  Pertinent phrase highlighted in bold.

Chapter 11 – Rules of the Road

ARTICLE VIII – Speed Restrictions

§ 11-805 – Minimum speed regulation

(b) Whenever the (State highway commission) or local authorities within their respective jurisdictions determine on the basis of an engineering and traffic investigation that slow speeds on any highway or part of a highway impede the normal and reasonable movement of traffic, the (commission) or such local authority may establish a minimum speed limit below which no person shall drive a vehicle except when necessary for safe operation or in compliance with law, and that limit shall be effective when posted upon appropriate fixed or variable signs.

Most states have similar verbiage.

[hotdogPi]

That wording seems to imply that if I'm driving 65, and something suddenly happens to my car that makes it impossible or dangerous to go above 30, I can go 30 and take the next exit. Is this correct?

[kphoger]

That wording seems to imply that if I'm driving 65, and something suddenly happens to my car that makes it impossible or dangerous to go above 30, I can go 30 and take the next exit. Is this correct?

How is that different than a state that doesn't post minimum speed limits at all?

[fwydriver405]

Before I-95 near the I-195 area was reconfigured with the Iway project, the speed limit thru a portion of Downtown Providence on I-95 South was 50 with a minimum of 40 (look at 2:28, at the right):