this post was submitted on 16 Sep 2023
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181
Welsh Conservatives lose vote to scrap 20mph default speed limit (nation.cymru)
submitted 1 year ago by DrCake@lemmy.world to c/fuckcars@lemmy.world
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The Conservatives in Wales lose their last ditch attempt to stop the speed limit change from 30mph to 20mph. The change will be coming into force on the 17th September

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[–] br3d@lemmy.world 2 points 1 year ago (1 children)

Perhaps this will help

[–] TWeaK@lemm.ee -2 points 1 year ago* (last edited 1 year ago) (2 children)

So their key points:

  1. Drivers cut their spacing as braking distances contract. Shorter gaps mean more vehicles can use the available road space, reducing standing traffic.
  2. Filtering at junctions becomes easier too. It is far easier for motorists to pull into traffic travelling at 20mph than at 30mph. So junctions work more efficiently and queues reduce.
  3. Motor traffic volumes decrease since slower speeds encourage active, sustainable and shared travel. Walking and cycling levels rose by up to 12% after Bristol’s 20mph limit[i].
  4. Buses operate more efficiently. The reduced length of queues means that bus journey times decrease, and become more reliable. Buses become a more attractive alternative to the car.

Don't really relate to 20 all that much.

  1. The space in distance between moving traffic is irrelevant, the following distance expressed as time will always be the same (~2 seconds). The space between stationary traffic is the same in both 20 and 30 zones.
  2. Filtering isn't about speed, filtering is about technique. It's about restraining your acceleration and leaving a bigger gap in front. It can be done at any speed - it's what you do when entering a motorway at 70 mph. Reducing the speed limit does not teach people how to filter.
  3. Bristol is a city, this post is about Wales as a country adopting 20 mph limits. I live near Bristol, and many Bristol roads need to be 20 - they're too narrow and there's too much going on (and that's not to mention the potholes..). That isn't true elsewhere in the UK, and certainly not throughout the countryside, even the countryside immediately outside of Bristol. However, even with the 20 limit, many of the roads in Bristol are not built suitable as 20 mph roads, and compliance in these areas is very low. Even buses do 30 in these places.
  4. The efficiency improvement for buses is negligible. Drivers let buses out. Again, this incorrectly attributes reducing speed limits to training drivers how to filter and how to drive in traffic.

If you want 20 mph roads, then build 20 mph roads. If you want drivers to drive better, train them.

[–] br3d@lemmy.world 3 points 1 year ago (1 children)

Just in general, can I ask what you're hoping to get from this thread? I mean, you're in the Fuck Cars community asking everyone to agree with you that today's driving is okay, that there aren't benefits from slowing down motor traffic and that we shouldn't expect people to act legally. It seems a strange battle to choose.

[–] TWeaK@lemm.ee 1 points 1 year ago

I'm just calling out bullshit political pandering in a blanket speed limit reduction as what it is: bullshit political pandering that doesn't even really achieve the goals it sets out to do.

I'm not against 20 limits, I'm not against increasing safety of vulnerable road users, I'm not against reducing the use of cars. I want those things to be done appropriately and effectively. This is not that.

[–] olafurp@lemmy.world 0 points 1 year ago (2 children)

That whole study is specifically aimed at 20mph. It does reduce speed but not exactly by 10mph. It’s going to reduce traffic time, casualities, pollution and increase walking and public transport use.

There is a lot to like and for the places that it doesn’t apply people can always put up a sign for 30. Ideally this is supported by traffic calming measures but that’s a longer more costly.

[–] TWeaK@lemm.ee 2 points 1 year ago

If they put up a ton of 30 signs then it probably would be alright. Eg, the main road through a village or town could stay 30, while the main high street and side roads would all be default 20. But that requires more than just a change in law to say "what was 30 is now 20", and they don't seem to be doing this. They're expecting financially strapped local councils to go through a process of assessing and assigning 30 limits themselves, at their own expense. It likely won't happen in most places, they simply can't afford it.

[–] TWeaK@lemm.ee 2 points 1 year ago

Also, if you want to refer to that blog post as a "study", we should look only at its sourced claims.

  1. Motor traffic volumes decrease since slower speeds encourage active, sustainable and shared travel. Walking and cycling levels rose by up to 12% after Bristol’s 20mph limit [^1]

This is specifically about Bristol, a city with narrow roads.

  1. Smoother driving with less wasteful braking and acceleration cut fuel use by 12% in Germany after 30kmph (18.6 mph) limits were implemented [^2]

I'm sure Germany have implemented speed limits efficiently, but the UK has a history of compelling local councils to implement traffic measures that increase fuel consumption and thereby increase fuel tax revenue. Regardless, Germany have not changed all of their 50 kph zones to 30 kph, like this law proposes.

  1. The Department for Transport’s speed / flow plots are in the COBA (Cost Benefit Analysis) manual - Vol 13 of the Design Manual for Roads and Bridges. This computer programme shows that urban traffic flow improves at lower speeds [^3]

Urban traffic flow. This law covers everywhere.

  1. The FREEFLOW project by the University of York, City of York Council and others... Slough experimented with this successfully in the 1950s on a single arterial road. [^4]

This experiment was from 1950.

  1. Shared Space also enjoys claims of shorter tailbacks and congestion. The concept relies on cutting traffic speeds to around 20mph or less for ‘eye contact’. Traffic experts Ben Hamilton Baillie and Phil Jones state "tailbacks of traffic during peak periods have also reduced. It seems that the ambiguous junction provides improved capacity for traffic and fewer delays than traffic signal control systems." [^5]

Urban design, referring to handling specific zones of congestion.

None of these points apply to changing the national speed limit for Wales from 30 to 20.

[^1]: Cycling City project and Active Bristol / Monitoring by Bristol City Council http://www.betterbybike.info/sites/default/files/attachments/Cycling%20City%20end%20of%20project%20report.pdf [^2]: An illustrated guide to traffic calming. by Dr Carmen Hass-Klau (1990) [^3]: Link to a copy of the COBA 2002 manual – Traffic Flow plots are in Chapter 9: http://www.leics.gov.uk/part_5.pdf [^4]: http://www.freeflowuk.net/index.php?option=com_content&view=article&id=73&Itemid=59 [^5]: Improving traffic behaviour and safety through urban design. Proceedings of Institute of Civil Engineering. Ben Hamilton Baillie, Phil Jones May 2005 http://www.icevirtuallibrary.com/content/article/10.1680/cien.2005.158.5.39

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