Is a plastic public realm really sustainable?

on Aug 03 in Uncategorized by
As a part of its highways investment programme, Birmingham City Council is installing secondary kerbs to address the issue of motorists parking on grass verges. To satisfy the Council’s sustainability objectives, recycled plastic kerbs have been specified in many of the proposed locations. The only problem is that local residents have noticed the plastic kerbs break upon impact.

New plastic kerbs in Eachelhurst Road, Sutton Coldfield

Birmingham’s new plastic kerbs are only lasting a few hours. Precast concrete kerbs generally last for about fifteen years. Granite kerbs last for at least 50 years, and then their chipped sides can be turned around, and so they often end up lasting for centuries.


In towns like Stratford upon Avon, the Council considers the whole life costs of the materials they use, and they consider the importance of image. They realize that in the long term, concrete and plastic kerbs are more expensive, and less sustainable, than a traditional material like granite, because they have to be replaced so frequently.

They use granite kerbs in Stratford. Even their double yellow lines are half the width of standard and they are painted in primrose yellow rather than toxic orange.

Most of the granite being used in the UK is from China, which might sound unsustainable, but when you break down the carbon footprint of this imported granite it’s within a reasonable range because of the products very long life.

Given the increasing trade relations between Birmingham and China, perhaps a commercially attractive deal could be struck so that all of Birmingham’s kerbs are in granite. This would make Birmingham’s public realm appear more prestigious, it would require less maintenance, it would reduce the city’s carbon footprint, and it would also reduce costs.

A typical street in Stratford upon Avon, granite kerbs and half width primrose lines

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Palace of Pugin by Nick Corbett


















  • Phil Sutton says:

    It is clear from these images that the kerb has been dislodged, but not damaged! the haunch detail is clearly not correct in this design, a backing of 150mm depth concrete to the top of the kerb is required, and this design would have dislodged be it concrete or plastic.

    The benefit from plastic, is these units can be manually handled by operatives, without the need for costly and cumbersome lifting aids, therefore reducing, disruption to traffic and speeding up lay rates.

    They are made from a blend of polymers that are generated from kerbside collection schemes within UK and manufactured within the UK! They can also be recycled again and again, therefore becoming a kerb for life. They also benefit being carbon netural as studies from a UK body has found aligning themselves to PAS 2050.

    Plastic kerbs dont contain silica, again reducing operatives and the gerneral public exposure to killer dust – while cutting kerbs – as outlined by the recent HSE study and prevention campaign.

    Over 300,000 units are in succesfull services across the UK with many local councils seeing the benefits of such units.

    • Transforming Cities says:

      Thanks for your observations Phil. Don’t highway engineers also have an urban design role to play? If so, they need to consider the appearance of the materials they use in our streets – colour and texture, and also the effect upon local character and identity; as well as sustainability, performance, and the whole life costs of materials. They need to ensure our cities have public realm strategies with a coherent palette of materials. The colour and  texture of Birmingham’s plastic kerbs don’t look authentic to me. They’ve been dislodged or broken in several locations, and so they detract from the city’s image, with all the costs that go with that.  I’d agree we need to consider new sustainable materials, but the appearance of the dislodged sections of plastic kerb in Birmingham suggest this material isn’t fit for purpose, even if the damage is a result of inept designers or contractors, the result is the same, it’s dangerous, unsightly, and a threat to the reputation of the highways department and the City

  • Phil Sutton says:

    Hi Nick,

    I can’t see how a road kerb, be it made of concrete or polymer has any real aesthetic or texture value, concrete within precast kerbs is a dull grey material, which can vary greatly in colour depending where the sand and aggregate is quarried. Polymer kerbs can be coloured to any required RAL standard upon specification, I don’t think this would be the case with concrete. Polymer kerbs can be made to a silver grey granite shade at a fraction of the cost to natrual stone

    With regards to the environment and sustainability, Polymer kerbs stack up greatly, utilsing waste polymer that usually blight our land and being made from a thermoplastic can be recycled again and again. The concrete lobby, open cast mine, and the production of portland cement produces more man made carbon emissions than all the worlds airlines put together!

    I understand the discussion if the kerb is to be used with a conservation area, wherein Granite products should be utilised. But in areas when the standard installation detail requires concrete and blacktop for the paving, I don’t really see it matters if the kerb is made of concrete or polymer, if both are equally installed in a correct manner with the relevant haunch detail applied, they’ll function perfectly well.

    Reverting back to the current installation within Birmingham, these images suggest to me, that a high containment kerb – similar to a Treif unit – would be required, as from the description this area is being frequented by HGV vehicle with constant over steering. Hence, why the local authority has tried a double kerb detail.

    • Transforming Cities says:

      Phil, you say real granite kerbs should be used in Conservation Areas, I agree, and they usually are, because of their attractive, robust qualities. Perhaps an unintended consequence of Conservation Areas is that excellent design and materials only get applied in protected, historic areas, and everywhere else gets second best. Surely good design and materials are appropriate for everywhere. When you consider whole life costs, good design and natural materials are usually more cost effective.

  • I’d rather not see plastic used in the construction of kerb stones for any community, conservation or otherwise. If longer road delays are required to make it happen then so be it. I’m also pretty sure that granite or other road materials can be sourced locally for such projects, in fact it would be more appropriate to use the natural stones of the area, if appropriate, for such ends.

    Penzance recently ‘re-paved’ its high street pavements with tarmac, the local community went up in arms at the councils poor decision and they pulled the whole lot up and re-laid it with Cornish granite. Proper job as they say down here. It would of taken a considerable dent into the character of this town had tarmac remained, luckily these things can be reversed. All too often people with no taste and poorly qualified are left to make decisions for the long term common good.

    We need to continually aspire to the best for all our common spaces.

  • David Lloyd says:

    It’s getting harder to find places to park these days, today 26/03/14, work started on my road to put a double kerb around the large grassed circle in our grove like road so people can’t park on it, so where can these people park now, it’s tight as it is and I have seen emergency services struggle to get around the road when cars are parked outside houses. The area in the centre of the road should be tarmac covered to stop the parking problem, this stupid plan is a bad idea and will cause plenty of problems in Overton road Acocks green B27, Our road was resurfaced 18 months ago and it would have been nice if we were asked if we wanted dropped kerbs at the same time which would have been cheaper for us and it would have been nice if we were all asked what we think should be done to help the parking situation in our road. Where are our visitors going to park, I’ll tell you where they will park, over other peoples drives which will cause trouble.

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