How is Mallard Way's asphalt faring 3 years on as policy comes under scrutiny?

Brent Council's justification for asphalt replacing paving - 2016

With the current controversy raging in Mapesbury Conservation Area over the replacement of paving with asphalt I thought it worth checking on the current state of Mallard Way, in Kingsbury NW(, which was asphalted 3 years ago.

For the most part the walkway is smooth although there are some shallow indentations in places which accumulate rainwater. The photos below suggest that there is some cracking beginning and mould/moss. which becomes a slipping hazard in wet or icy weather, is beginning to form in places.

Next to a tree pit

Cracking beginning

Moss/mould

The road to Hell is paved with Brent's good intent (or asphalt)

 

Recent paving in the Barn Hill Conservation area - why not Mapesbury?

A Mapesbury resident who is a retired Civil and Structural Enginer (MIStructE and MICE) has carried out a pavement survey of Dartmouth Road where Brent Council wishes to replace the paving in this Conservation Area road with asphalt.

The survey has been forwarded to the  Council and members of the Mapesbury Residents Association.

The works have been temporarily suspended giving time for  review and it is hoped that in the light of the Council's Climate Emergency Declaration an assessment will be made of the comparative carbon footprint of renewing broken paving compared with taking paving up and replacing with asphalt.

Dartmouth Road Pavement Survey.

Carbon footprint of proposed replacement of paving slabs by asphalt

Date:  20.11.19

This report is based on a detailed survey of the pavements on both sides of Dartmouth Road:

A:  between nos. 103 to 131

B:  between nos. 60 – 92

Which is ¼ of the length of Dartmouth Road.

C:  between nos. 1 – 24.  This last section has recently been repaved and is in excellent order.  See appendix for the survey results for this section.

Pavements are on average 2700 mm. wide and are formed using 600 x 750 and 600 x 600 precast concrete paving slabs. The width consists of two of each size staggered: 

(2 x 750 ) + ( 2 x 600 ) = 2700.

Each property is approx. 10 m wide and so there are theoretically 16 ½ x 4 = 68 slabs per property. But many properties have vehicle crossovers which reduces the number of slabs. The crossovers are either of concrete or block paving construction or a mix of one of these plus paving slabs.  There are also a very few tarmac crossovers.

Where trees occur the paving is extended upto the tree or there is a resin gravel type infill upto the tree, or occasionally tarmac or nothing with the soil visible. Whatever has been installed next to the tree has usually failed in some way and is uneven.  These areas have the most trip hazards.

Concrete and concrete block vehicle crossovers have performed best and are often in good serviceable order. Any area of crossovers that is surfaced with paving slabs is in poor condition with on average over 1 / 3 of the paving slabs cracked.

Good condition slabs .			Cracked slabs .
Between crossovers	At vehicle crossovers	Total	Between crossovers	At crossovers	Total
1540	243	1783	129	72	201
			% of total 129/1540= 8.3 %	% of total 72 / 243= 29.6%
Whole length of Dartmouth Road pro-rata  (i.e. x 132 / 32 )
6350	1000	7350

It can be seen that paved crossovers contribute nearly 4 times the rate of cracking that occurs  in areas between crossovers.

It can also be seen that within crossovers there are 243 – 72 = 171 uncracked slabs which is comfortably more than the 129 cracked slabs within the paved areas between crossovers. So when the defective crossovers are replaced there will be sufficient uncracked slabs recovered to replace all the cracked slabs between the crossovers.

We can extrapolate this detailed survey to the whole of Dartmouth Road because a visual inspection indicates that the area surveyed in detail here is of the same configuration as the whole of Dartmouth Road and the total figures for the whole road are shown in the table. 

The plan proposed by Brent Council is to remove all the paving and replace the crossovers with block paving and to infill between the crossovers using asphalt.

Therefore the number of paving slabs to be removed from between crossovers and dumped is 6350 slabs.  The slabs are 50mm thick

The average weight of a slab is (.6m x .675m x .05m) x 2000 kg / m cube = 40.5 kg

Therefore the weight of slabs to be removed = 6350 x 40.5 / 1000 = 257 tons. These slabs have to be lifted, piled up and then grab loaded onto a lorry and taken to a dump. Such loading will achieve about 10 tons per typical 8 wheel lorry giving rise to 26 lorry movements. And the dumping will attract landfill tax. More seriously, these slabs will remain in landfill unchanged for centuries.

Asphalt requires a well compacted base layer of stone which will have to be imported because the sand / soil / clay found under the existing slabs when lifted will need improvement. 

The area of new asphalt will be the same as the paving removed = 6350 x 0.6 x 0.675 = 2570 m square. 

Allow for a restored formation thickness of 75mm, this will require the removal of 75mm of existing soft material ( to maintain existing levels) and reinstatement using 75 mm of stone material. So the volume of material removed and replaced will be 2 (1 removal and one replacement) x 2570 x 0.075 = 385 m cube = 770 tons. Which at 15 tons per lorry for this type of material gives rise to 51 lorry movements.

The amount of asphalt required if 20mm thick will be 2570 x .02 = 51 m cube = 100 tons at least, requiring another 10 lorry movements.

So the total weight of materials being lifted and moved is 257 + 770 + 100 = 1,127 tons requiring 26 +5 1 + 10 = 87  lorry movements. 

The lorries will have to travel to a dump outside London and the asphalte and stone will have to be brought in from a quarry, also well outside London.  This represents a lot of diesel at 10 mpg! And this is just Dartmouth Road. For the whole of Mapesbury Estate there will be at least 6 x these quantities, i.e nearly 7,000 tons of materials dumped or imported, involving 500 plus lorry movements. 

Furthermore, since Brent plans to change all the pavements in the Borough for asphalt, the quantities will become huge.

It is obvious that the proposed use of asphalt to replace existing slab paving is totally unacceptable on carbon foot print grounds for material handling and transport and the energy intensive manufacture of the asphalt itself, which is a heavy crude oil hydrocarbon based product. Levelling the slabs in situ would have minimal carbon foot print and lead to a pleasing durable solution appropriate for a Conservation Area. 

Appendix:  P

Appendix:

The section of Dartmouth Road between Mapesbury Road and Exeter Road has also been surveyed in detail as follows. This section was re-laid using slabs 5 years ago and is in very good condition and shows how successful slab paving can be when well laid.

Survey on Dartmouth Road between numbers 2 and 14 and the opposite odd numbers side which is in equally good condition
Good condition slabs .			Cracked slabs .
Between crossovers	At crossovers	Total	Between crossovers	At crossovers	Total
1043	No paved crossovers, all are conc. or blocks or tarmac	1043	19 *	No paved crossovers, all are conc. or blocks or tarmac	19
			% of total 19/1043 = 1.8 %		% of total 19/1043 = 1.8 %

About half of these cracked slabs are so finely cracked it is difficult to see the crack because they have not moved having been very well laid.

This table applies to only 15 % of Dartmouth Road and so would not affect the pro-rata totals used above very much and in fact further support the case for retaining all the existing paving in Dartmouth Road.

Asphalt wars break out again as Mapesbury residents challenge Brent Council

Residents in Dartmouth Road have taken on Brent Council over the proposed asphalting of their footway LINK. They claim that while there are strict rules involving the protection of their Conservation Area regarding changes to their properties, Brent Council is ignoring the spirit of such legislation in its plans to replace paving with asphalt.

The policy was challenged three years ago over the asphalting of Chandos Road with a petition launched on 38 degrees. LINK

There are, I understand, now getting on for 150 signatories on the Dartmouth Road petition to the council opposing the action and the operation which was due to start today has been suspended for a week.

Meanwhile the image above shows Grendon Gardens in the Barn Hill Conservation Area which was re-paved with brick blocks and paving stones after the asphalting policy was introduced.  When I tweeted a photograph of the work at the time someone suggested a Brent councillor must live in the street - I am sure that is not true but residents are looking for consistency in Council policy.

Is your road surface/footway due for resurfacing/reconstruction by Brent in 2018-19?

The last meeting of this administration's Cabinet on April 9th will approve spending on the borough's highways maintenance of £3.5 million. Normally TfL would contribute an additional capital sum for spending on the borough's principal roads but this has been 'paused' under their 5 Year Plan, representing a loss to the borough of £882,000. However, each London borough has been asked to submit two principal roads for consideration for maintenance work and Brent Council has submitted Wembley High Road and Kilburn High Road. A decision is likely by the end of April.

The report to Cabinet points out that Highway infrastructure is the most visible, well-used and valuable physical asset owned by Brent Council. Highway assets include:

• 505 km (315 miles) of roads; 

• 847 km (529 miles) of pavements; 

• 53 bridges and structures; 

• 24,500 road gullies; 

• 10,000 street trees; and 

• 22,848 street lights and other illuminated street furniture. 
 

The value of this asset is estimated at around £3.8 billion 

 

The £3.5 million to be spent on this infrastructure is dwarfed by the £18 million of Community Infrastructure Levy the Cabinet allocated to replacing the Wembley Stadium Pedway with steps. 

Spending will be on:

• Major and minor pavement reconstruction; 

• Major Road resurfacing; 

• Preventative maintenance; 

• Improvements to the public realm, and 

• Renewal of Road Markings

 

Previous road works in Engineer's Way

These are the Highway Maintenance plans for 2018-19. 

The 'Rhino Imprint' earmarked for Harlesden High Street and Engineer's Way, Wembley is a synthetic material. Details HERE. The Civic Centre is on Engineer's Way.

Asphalt/Brick on footways refers to asphalt replacing paving stones for the main footway and brick for dropped kerbs at driveways and junctions.

Brent Council challenged on pavements policy

 

Extract from Brent Council document

Following the 'pavement' meeting of Council officres, councillors and residents LINK to discuss the repaving of Brent streets with asphalt rather than paving slabs, local resident Simon Campbell has written to councillors:

Thank you for taking the time last week to meet with residents regarding Brent Councils new tarmac policy.

When the meeting had finished, rather than being left re-assured as was promised by Chris Whyte, I (along with many other residents) was left with the distinct impression that this policy seems to have been adopted with little or no consideration to either the planning or environmental impact and Transport seems to operate in isolation from the rest of the Council.

I found it quite incredible that Chris Whyte would attempt to portray Geary Road as a positive example to the residents of Chandos and Cranhurst, given that Dawn Butler MP has already been involved because of the anger many residents there have expressed with what has been done by the Transport Department and their contractors.

I am still waiting to hear what precisely this new lighter material is that Brent Council are supposed to be using on Geary Road, perhaps you will have more success in getting this specific information?

As councillors, you are supposed to represent constituency representatives and it was very apparent how disconnected your standpoint on this issue was, when compared to the views expressed by the majority of residents in both of the streets that were consulted. Please find attached the stats for both Chandos and Cranhurst.

Instead of Tony Kennedy repeating his obviously biased views, I would like to hear from the department heads of both Planning and the Environment about the basis on which this policy was decided and approved.

I have noted that Brent Council likes to portray itself as a “green” Council, but I along with many other residents found it impossible to reconcile quotes from Brent Councils own website regarding its supposed green credentials and its responsibility to protect and enhance the local character of Brent.

Unfortunately, Brent Council have proven form on this subject, the original plan to demolish the old Library and destroy the adjacent Plane tree touted by the Council made all the more outrageous by the fact that it is supposed to be at the centre of a conservation area.

Many locals actually do care about their area, their history and local character – something the Council soon found out. It should have been promoting and enhancing – not undermining this important aspect. This casual disregard for the areas architectural heritage seems to have surfaced again with this policy.

Both Local and Central government are supposed to be working together to reducing the amount of rain water being channelled into the sewers and maximising the amount of runoff absorbed at a local level.

This important responsibility is not going to be answered by applying a huge amount of water impermeable, petroleum based product (that continually leaches solvent and oils into the earth and onto people and animal’s feet) and decreasing further the amount of moisture onto the clay subsoil on which most of London is built - thereby increasing issues of subsidence as the clay is further isolated from moisture.

You may wish to reflect on one of Brent Councils own policies as regards water impermeable surfaces and the negative impact they have and the reason this measure has been put in place by virtually every local authority in the UK.

I have also noted that there will be a substantial increase in solar gain by installing a huge amount of matt black surface that will attract the heat, whereas the concrete pavers because of their colour/finish, help to reflect much of this solar energy and that this important negative aspect seems to have been ignored.

I look forward to your detailed responses to the above.

Regards,

Simon Campbell.