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ABD 20s Senseless

Factual Background on 20mph limits

By 27th May 2020April 25th, 202115 Comments

Wide-area 20mph zones are proliferating, despite sound evidence presented to the DfT that these zones do not improve road safety, but can: (1) actually increase fatal and serious injury risk for vulnerable road users, (2) do increase vehicle emissions, (3) do waste valuable productive time by lengthening every previously 30mph journey by up to 50%, and (4) do impede the progress of emergency service vehicles.


(1) Casualties:

Research carried out for the DfT (see did not provide statistically significant evidence that wide area 20mph limits reduce vulnerable road user casualties. Joint ABD/ Bridgstock evidence presented to the Scottish Rural, Economic and Connectivity (REC) Committee in February 2019 provided documented evidence of increases in vulnerable road user deaths and serious injuries after the implementation of some 20mph zones, which had replaced previously 30mph ones (

Around 2% of UK urban adult-, and 0.6% of urban child-, pedestrian casualties are fatalities. The Ashton and Mackay curve (below; from DfT Web Publication No.16 – Relationship between Speed and Risk of Fatal Injury: Pedestrians and Car Occupants, TRL, Sep 2010) tells us that for this to the case, the average impact speed in 30mph zones is already below 20mph

The ABD contends that 20mph zones increase driver distraction and workload through increased need to speedometer-watch. This degrades crucial observation, hazard perception, -response and avoidance skills. In tandem, vulnerable road users have been given the highly inappropriate perception that 20mph zones are “safer”; so they behave more incautiously in them. This is a perfect recipe for vulnerable road user accidents in 20mph zones to involve a 20mph impact speed; while at higher speeds, the less speedometer-obsessed, more situationally-aware vehicular road user has time to brake/take evasive action; thereby reducing impact speed or even altogether avoiding an impact.


(2) Emissions:

Per the schematic for NOx emissions shown below, for vehicles to travel at speeds at or below 20mph requires the selection of lower gears, which means higher engine revolutions and increased emissions. Transport for London’s own data (at provides a catalogue (pp.18-32) of curves for various emissions vs average speed by vehicle type scientifically corroborating this fact – which should anyway be blindingly obvious to anyone with even rudimentary automotive knowledge.

(3) Journey Times:

To travel, say, 60 miles at 30mph takes 2 hours. The same journey at 20mph takes 3 hours: 50% longer. The time taken for every previously 30mph journey travelled at 20mph is therefore lengthened by potentially up to 50%. In the year following the imposition of an 80kph blanket speed limit on France’s previously 90kph rural roads, there were no significant casualty reductions (as had been expected by some so-called “road safety” advocates), but the policy did succeed in deflating the French rural economy by 4.4€Bn (see: Similar lost productive time arguments clearly also apply to 20mph zones.


(4) Emergency Vehicle Response Times:

It has already been documented ( that the carpet-bombing of London boroughs with road humps caused more fatalities through increased emergency vehicle response times than the humps had notionally saved. Similar considerations apply to wide-area 20mph zones; many of which are being implemented in areas in which it is impractical for drivers to pull over to let emergency vehicles pass. Likewise, exceeding the speed limit to expedite their progress is no defence against an illegal speed NIP; so highly inadvisable.


  • Brian Gregory says:

    The ABD supports the targetted implementation of 20mph limits where the road engineering configuration is consistent with the use of such a limit; where other measures (e.g., temporary, time-specific limits) cannot be used; and a 20mph limit is appropriate to a very specific local risk environment. We do not condone the indiscriminate, unnecessary and economically costly proliferation of wide-area 20mph zones where the road configuration is not conducive, and the measures are being proposed purely to make motor vehicle use less pleasurable, more difficult, more time-consuming and more costly. Visit to register your support for the ABD’s campaign to prevent the .

  • Brian Gregory says:

    London Mayor, Sadiq Khan’s, has intensified his continuing witch-hunt aimed at the extinction of freedom of private mobility, through the misuse (potentially illegally) of emergency Traffic Orders during the Covid-19 outbreak. These have been used to implement carriageway narrowings, superfluous cycle lane widenings, and so-called “Modal Filters” (roadblocks to everyone else capable of speaking understandable Queen’s English). This has incensed, amongst others, London cabbies: The ABD has in progress a campaign to oppose these fundamentally anti-mobility and anti-democratic policies. Visit:

  • Peter Horton says:

    Fully with you Brian. Have also written to my MP about the folly of the excessive provision for cyclists at the expense of road space for vehicles and asked if they have considered the restraints against commuters cycling – i.e. distance, terrain & weather, and then the need to avoid public transport which boils down just to car use, so should actually be making more provision for car parking and smooth motor traffic flow. From the response I gather that he may actually forward my questions to Grant Shapps, but we can only expect some bland nonsense reply, I fear.

    Best wishes from Ripon.

  • Brian Gregory says:

    James Burdass is encountering a similar mix of ignorance and political apathy in parts of London. One Deputy Labour leader he met knows there are well-founded reservations about their closed-mind, unbounded enthusiasm for 20 limits. But in a 70% Labour controlled Council, they don’t want to be confused with anything as inconvenient as the indisputable facts about their effectiveness. They also seem oblivious that 20 limits near schools are only effective and needed for about 4% of the year when the premises are in use, opening or closing; so time-delineated lower limits are more appropriate. The words horses, water and drink come to mind.

    • James Burdass says:

      I know the Deputy Leader you mean, Waltham Forest.

      Tried to educate them into targeted measures to slow cars down when there is good reason to do so in front of schools rather than over a wide area, a sensible suggestion but no luck in LBWF.

      In London, 20mph seems to be a party political issue. Many outer London Conservatives still support the national default limit of 30mph.

  • Brian Gregory says:

    Sanity has currently prevailed re. the proposals for a city-wide 20mph urban limit in Birmingham. ” We are delighted that the absurd plans for a #20mph limit across #Birmingham have been reigned in by @CharlotteV (pp @grantshapps) ✅ Though Councillor Zaffer will continue to push for them until the voters of #Lozells have the sense to elect someone else”.

  • Across wide swathes of the capital, councils are playing fast and loose with the law and using emergency powers not intended for that purpose to impose road narrowings/ roadblocks (euphemistically called “modal filters”) and unnecessary cycle lane widenings. This appears to be purely about furthering an anti-personal mobility agenda. It particularly adversely affects the elderly and the infirm – who often have no alternative to private car use – but also increases congestion, unnecessarily elevates vehicle emissions and wastes precious economic time. This is time that can be ill afforded, as the whole country seeks to climb out of the deep economic well created by the Covid-19 outbreak. ABD’s London Campaigns Manager, Roger Lawson, is spearheading a legal challenge ( to measures implemented in the borough of Lewisham without adequate public notice or consultation. If you know of any instances of e.g., emergency vehicles being delayed by these (or any other traffic impeding) measures in the London area (or indeed anywhere else) and that have had adverse health implications for anyone, this is a failure in a local authority’s basic duty of care; for which they may be punishable in law. Please email: if you do.

    • James Burdass says:

      COVID-19 wasn’t supposed to bring with it rampant inconsiderate cycling and ‘Low Traffic Neighbourhoods’.

      Using emergency powers, Park Lane is now down to 1 lane Northbound.

      Worst Mayor ever thinks that is an effective management of the traffic?

  • It seems that the 20mph contagion is spreading, despite a paucity of evidence to justify the implementation of such limits. It is apparently intended that Wales will adopt 20mph as the default urban limit – with little or no public consultation and supporting evidence limited to one report obtainable at: This appears to be a digest of supportive documentation for 20mph that glosses over both the evidence of the Atkins AECOM/ Maher 20 mph report (no statistically significant evidence of casualty reductions) and TfL’s evidence that levels of all problem emissions will in practice rise at 20mph relative to the situation at 30mph (at The focus of the Welsh report is on”active travel”: i.e., finding excuses to force you out of your car. Continuing abuse of the Covid-19 emergency powers is being used to accelerate the pace of implementation of these undemocratic, consultation-free measures.

    • James Burdass says:

      Why does evidence not prevail over virtue signalling?

      There are pictures of blue skies and greenery associated with 20mph and cars giving off pollution at 30mph, when the reverse is true per the 20’s senseless web-site.

  • Please be aware that we have a standing request from Steve Bird (; 07966-499579) at the Telegraph newspaper for information on road closures/ narrowings brought in under the guise of Covid emergency powers, which have entailed demonstrable and documented adverse effects on emergency vehicle response times. Please contact Steve direct if you are aware of any such instances. Thank You.

  • Participated in a Radio Hull interview this morning (17/08/20) re. local council’s unnecessary and unhelpful road space reallocation programme from motorised vehicles (97% of traffic) to cycles (3%). Tried to convey reasonable and balanced views, but there’s always a concern as to what slant BBC editors may try to put on it.

  • Grant Shapps’ incompetent call to local authorities “to make significant changes to their road layouts to give more space to cyclists and pedestrians, & help embed altered behaviours and demonstrate the positive effects of active travel” – is the root of all the road restriction problems currently happening ????

    Fortunately politicians are disposable items, and their policies are reversible.

  • Quoted verbatim from Dave Buchan on ABD’s Facebook page: “Back when Local authorities actually had brains, there was a perfectly good real consultation process that had to be completed with residents, local public transport AND all 3 of the emergency services prior to any road closures, so that public safety & response times could be met . Sadly common sense no longer prevails and people will die in the mad rush to slash vehicular access.”
    It’s impossible to quibble with that sentiment………….

  • Brian Gregory says:

    It appears that there is a head of campaigning steam building to legally challenge the lunacy of the implementation of the Welsh blanket 20mph urban speed limit. Similar developments may well follow regarding the even more economically suicidal proposals to reduce stretches of Surrey & Kent national speed limit roads to as low as 20mph also.

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