Examples of Non-uniformity in Bristol's Speed Limits.

It's no secret that I opposed the 20mph limits in Bristol, not because I believe that speeds of 30mph are sensible on typical residential streets—quite the opposite. However, it's crucial to recognize that people do not drive at unsafe speeds solely because the limit allows them to.While reaching 30mph down streets like that is not safe, enforcing speed limits down such streets is difficult.

This is why the UK has other laws, such as careless, reckless, and dangerous driving.
Driving at obviously unsafe speeds on these streets, causing harm, and then claiming in court "I wasn't speeding" would never hold up.

The speed limit could have always been set at 20 or 25 mph on side streets. Instead of constantly changing the limit through differing road standards, the UK relies on the presence of street lights to indicate a limit rather than using signs—similar to the national speed limit, which is represented by a symbol rather than a number.
If we didn't trust that most people would drive responsibly, we shouldn't be giving them a license in the first place.

When driving on a street like Bishop Road in Bishopston, I naturally settle at around 22mph, even when the limit was 30mph, which was far below the speed limit. It's not the limit restricting me, and that's precisely how it should work.
While we all witness people driving too fast daily, the speed limit isn't to blame for this behaviour. Observing individuals exceeding safe speeds every day doesn't mean the speed limit is at fault.
No one who races at unsafe speeds down residential streets can be considered sensible. These drivers are overwhelmingly not the type to slow down just because the speed limit is set lower.

There is a common misconception, which I also used to believe, that speed limits are automatically adhered to once set or that people who speed will only exceed a set amount over whatever speed limit is imposed. In reality, drivers relieved of the pressure of an overly low speed limit rarely abuse a higher one. In some cases, an increase in the speed limit can even lead to a decrease in actual driving speed. However, this misconception puts pressure on councils to set limits as if that were the case, resulting in limits lower than engineering recommendations and creating inconsistency. Speed limits serve as a legal tool to identify reckless drivers; they do not dictate traffic speeds.

Although many people wish speed limits worked in that way, they do not, even if you try to use them as such. The constraint lies in understanding and accounting for real-world human behaviour. Ignoring this reality leads to over 90% non-compliance, rendering the limit ineffective and similar to having no speed limit at all.

That said, there is evidence to suggest that setting a speed limit slightly below engineering recommendations may improve safety.
So, much as my cognitive bias is towards trusting people and putting more emphasis on drivers driving to the prevailing conditions, not by numbers, I can't let facts get in the way of that.
The lack of an option to set 25mph limits in the UK starts to become an issue there. I think a 25mph limit would be effective on such places such as Gloucester and Whiteladies Roads etc, where 30 is rarely intuitive or sensible.

In short, limits may make a little bit of difference, to be effective, they need to match the road they’re on and consistently seem reasonable.
Exceptions to this need to be just that, exceptional.

The main point is that speed limits should primarily focus on addressing reckless driving rather than penalizing ordinary behaviour. This principle should apply to any law and should not be a matter of controversy.
My concern, in this context, is not so much about including side streets but rather the inclusion of numerous wider, higher standard, and main roads.
Not just that, it's the way that some roads have been included but not others and the inclusion criteria does not seem to be based purely on obvious engineering differences, this means there's inconsistency and non-uniformity and that is a known factor that helps to create apathy towards speed limits.


It doesn't seem that many limits are determined by road design or speed surveys. Instead, it appears to be influenced more by individual opinions. This could be because there's a notion that many drivers can't be relied upon to adjust their speed appropriately based on conditions. However it's somehow synonymously expected that these drivers will follow speed limits, even when the limits change in a seemingly arbitrary locations.

This is the best example comparison I could think of to make my point.

I have come across more than one 20mph speed limit advocate who has had reservations about the inclusion of some higher standard roads.

Side note, Bristol is not as bad as Cardiff.
Cardiff has started putting 20 limits on roads mostly with complete indifference to engineering standards. Roads that already seemed under-posted as 30 limits are now being made 20 mostly with no changes to the engineering of the road.

TL:DR, here's a summary of the sort of things I'm getting at without examples. 
1. There are main roads that are identical in standard, often built at the same time to the same standard,  some are included and others not.
2. There are roads that are 20mph that a build to a higher standard than other roads else where in the city that remain 30.
3. In some places the speed limit changes seemingly without reason or there are journeys you can do along main roads where the speed limit changes several times along the journey seemingly without reason.
4. In some places the speed limit can change in the opposite way to the way the character of the road would tell you to expect it to.
5. 20 limits outside schools on otherwise excluded roads are full time, this only undermines any effect the lower limit may have at school times.

Examples

What should be troubling to people for or against the 20 limits is that there are roads out there that are identical in standard some included some not, doing this would make sense if speed limits were something you just set and expect everyone to just go under that speed.

That's how I used to assume they worked before I had any knowledge as to how you set speed limits.

In some areas, you might find roads that are close together and have identical standards, yet some have speed limits of 20mph while others have limits of 30mph
The best examples of this are around Sea Mills and Combe Dingle, some are 20 (Westbury Lane and Combe Lane) while others have been kept 30 (Sylvan Way, Shirehampton Road) this seems to be based, not on road standards or measurement of average speed, but on how important the road is. That shouldn't be relevant when setting speed limits.
In Whichchurch, Whitchurch Lane and Ridgeway Lane are both excluded however Fortfield Road is included even though it seems to be a road built at exactly the same time, to the same standard, only the latter is much straighter. There are many more examples in other areas.

When you encounter roads with identical standards but different speed limits, it conveys a poor message to motorists, as the variations appear nonsensical. If they had, for instance, opted to maintain the 30mph limit on all A-roads, despite varying road standards, it would be inconsistent. Yet, the reality is even more confusing—they manage to consistently exhibit inconsistency.

There are quite a few journeys you can do in Bristol where if you stay on the main roads the speed limit remains 30 for the majority of your journey, for example driving from St Anne's to the A4 at Brislington it's 30 throughout on unclassified roads, in other areas like driving from The Gloucester Road to Clifton on B-roads, it's 20 throughout and then there are journeys, particularly in the North East of the city, where the speed limit fluctuates several times throughout the journey for seemingly no reason as if someone threw darts at a map with their eyes closed.
There's no obvious reason to me or likely most motorists why Birchwood Road in St Anne's has been left at 30 but Redland Road in Redland is 20.

There are roads in Bristol that are in a heavily urbanised area that are still 30 such as Redcatch Road, Guildford Road, Whitchurch Lane, Long Cross, and East Dundry Lane while there are other roads that are non-urban or urban with a higher standard that are 20 such as Portview Road, Eastgate Road, Kingsway, Midland Road, Redland Road and Pennywell Road.
The reason I single out those last three is because they were all the roads The Bristol Post measured the non-compliance levels at over 90%, on Pennywell Road it was 97.5%!
It's difficult to relate to someone who could look at those sorts of levels of non-compliance and not see that as indicative of an incorrectly set speed limit.

Is that sign backwards?

I can think of 3 places where the speed limit changes counter-intuitively, ie it goes from 30 to 20 in exactly the place one might expect it to go from 20 to 30 or 30 to 40.

The first is Kingsweston Lane, as the road goes from urban to rural the limit decreases from 30 to 20 in exactly the place you might otherwise expect it to increase.
I'm not saying it should increase there, it might be because people might expect to be able to speed up, if that's the case then it's a failure of the road design. There is a school further up, but children don't walk along here because there is a segregated footpath, of course under ideal conditions the school is closed.
If you really want to make the road safer for people to cross at the end of Napier Miles Road then the thing to do would be to install a pedestrian crossing or refuge by the junction and or have some flashing lights at school times.
There's no point just sticking some signs up to make people think the road is going to be a lot safer.

The second is on Broad Walk, it's another example of a 20-limit that’s a higher standard than many 30-limit roads. Most of it is a long, fairly straight road, lacking in parked cars with set back frontages, and excellent forward visibility, this section has a 20-limit, towards the end there is a park on one side and a row of shops on the other, as you get to this bit the speed limit rises to 30. I think they should have left the entire road at 30, but what you don't do is put a sign telling people to speed up here.

The third is the example that first led me into doing more research into how speed limits get set because it seemed so out of place it led me to Googling "arbitrary speed limits".
It's the 20 limit at the end of Cumberland Road. Most of that road is a 30 limit through a residential area, as you come to the end of it and into the purpose-built Cumberland Basin junction complex the speed limit goes from 30 to 20 in exactly the place you might otherwise expect it to go from 30 to 40.

Some roads seem to have been included, not because it wasn't up to the standard required to keep it 30, but possibly to appease local people's "concerns about speeding".

In other words, there was already a genuine problem with speeding, so the solution was to drop the speed limit. I suppose this could be said about a lot of roads, or the whole scheme in general, but Stockwood Road comes to mind. I was sat on that road one evening in my work vehicle and lots of people were hoofing it past me at ridiculous speeds. Yes, this was after the 20 limit had been put in place.
This is possibly down to the belief many have that if you set a speed limit very low, people who genuinely drive too fast will only go 5 or 10mph over the posted limit. It's a belief so prevalent and so wrong, you may as well be trying to convince me that leprechauns exist or that Brexit was a good idea, no that isn't true. 

Clanage Road used to have a 40 limit, they made it 30 and when that didn't work they decided to turn it up to 11 and made it 20, still with no changes to its engineering. Only now, there's a pedestrian crossing giving people a safe place to cross, it's also another road that's of a better standard than many other excluded roads.

The idea that the way you do something about idiots going stupid speeds along residential roads is to prohibit the behaviour of those going speeds right down into the low 20s is what I find really disheartening. They're the sensible drivers, they're the ones you should be encouraging. The idea that you drop a speed limit to try and do something about genuinely high levels of speeding is, at best, disingenuous.

There's a few places where the speed limit changes and I have no idea why, at least if the road is near a school I know why it changes even if that's not relevant at the time. This example is on Parry's Lane and I quite genuinely don't know why this speed limit changes where it does, just seems random.

Self-explaining? Answers on a postcard, please.

At this point, it’s worth mentioning that DfT guidelines state the following; "Speed limits should be evidence-led and self-explaining and seek to reinforce people's assessment of what is a safe speed to travel. They should encourage self-compliance.
Speed limits should be seen by drivers as the maximum rather than a target speed".
They then contradict this by recommending that mean average speeds are used for setting speed limits rather than the 85th percentile speed.
I don’t know why an average would be used as a basis on which you set prohibitions for anything.
However, at least there are actual guidelines stating to use traffic speeds as a basis for setting speed limits.

The speed limit is the fastest you can go, under ideal conditions?

There are permanent 20 limits outside schools in violation of this notion, this is bad for a number of reasons.

No one is or should be arguing that you shouldn’t slow down outside a school at opening and closing times.
The character of these roads is often materially difference at school times, even getting to 20mph at these times may be a bit of a challenge if you've got sense, often it can be unintuitive to go faster than the mid-teens.

Where there's an otherwise excluded road and you go past a school, the limit drops, the limit is permanent rather than at school times only.

That means the speed limit drops even if you drive along that road at 3am, and to anyone familiar with the road it will change for no reason, and they know it! Then there's also a sign a bit further along telling you to speed up again, for no reason.

If there are speed limits that change for literally no reason, then how are you supposed to get people to respect them when there is a good reason, ie, it really is school end time.
You might think using 3 am as an example is hyperbole, but that doesn't matter. There are plenty of other times when it’s irrelevant. The speed limit isn't meant to just be the fastest you can go, it's the fastest you can go under ideal conditions.
The council claims that compliance is higher by making them permanent, however, if you ask motorists if they are more likely to obey such limits if they're part time, they overwhelmingly said they would.
These to me are just another example of the council showing their contempt to motorists.

Here, but not there.

The final example type is too numerous to name them all. There are roads included that are of a much higher standard than other roads that are not.

There are quite a lot of urban main roads that are lined with cars and frontages that have been excluded; for example, Long Cross, St John's Lane, Bishport Avenue.
Then there are the 20 limit roads that are of a much higher standard to those that have a limit of 30, for example Kingsway, Pennywell Road, and Eastgate Road.
Unlike some of the remaining 30 limit roads, those three are all modern roads engineered for a 30mph speed limit. Eastgate Road unlike many of the excluded roads lacks frontages, pandas, and parked cars it is long and straight with forward viability for both motorist and pedestrians. There's no way you'd naturally drive speeds along there under 20mph.

Then there are a few roads where I think they might only have been included because no one thought not to include them, such as every tiny cul-de-sac off an excluded road for example Parry's Grove, getting to 20 down there would be a challenge, there are roads through industrial estates like Day's Road or Albert Crescent.

It's not all 20 limits, there's a 40 limit through Sea Mills on the Portway, which makes sense. However, it starts about 600 yards before it needs to in an arbitrary location and stays 40 all the way to Shirehampton so that traffic entering Shire no longer encounters a drop in speed limit in line with a change to the character of the road.

 Why does this matter?

Even though I am saying speed limits don’t make much difference to actual traffic speeds, that's demonstrably the case. Again, there's a need to account for real human behaviour.

However, for what difference they do make, uniformity matters in getting drivers to take speed limits seriously. If the speed limit changes constantly, for seemingly no reason or you’re on a road of an obviously higher standard than you were before but the limits lower etc, all this helps to create apathy towards speed limits.
If you set rules that show people contempt, they're not going to reciprocate that by respecting it.
By including main roads, sat-navs will no longer be able to see them as faster, and may direct more traffic down side streets. Of course you also have the issue of pedestrians being told to expect traffic to be going slower than it actual is and it makes it much harder for the police to target those who genuinely treat the roads as a race track.
A better way to have done it would to have kept all main and higher standard roads 30, main roads with shops 25, part-time 20 limits outside schools and side streets 20.
There was a review of Bristol's the limits in 2019, I thought would have looked into the non-uniformity.
From what I can tell it's finding were all ignored including roads where most respondents did say the limit should be raised and two roads that saw actual speeds increase. The consultation response at the end also came with an "I ❤️ 20mph" logo attached, they didn't even pretend to not be impartial.

What's more confusing is these schemes are predicated by people who will very vocally pronounce that "people should obey speed limits", while doing exactly the thing that drives up non-compliance to ridiculous levels and makes breaking the speed limit much more normal and socially acceptable I find that dissonance confusing.

A friend said to me, that my mistake is "to try and apply logic and reason to what they are doing".

Unfortunately for anyone to complain about the speed limits some people are determined to assume the person doing so has a nefarious motive and still be immediately dismissive of every point you make.