§ Motion made, and Question proposed, That this House do now adjourn.—[Mr. Nicholas Baker.]
2.30 pm§ Mr. Tim Smith (Beaconsfield)I am delighted to have the opportunity to raise the subject of the noise and spray benefit of porous asphalt in motorway and road construction. I congratulate my hon. Friend the Minister for Roads and Traffic on his appointment to that important post, and thank him for staying so late in the afternoon, having already initiated and replied to an important debate on road safety.
The starting point for my remarks is the problem in my constituency of increasing noise from motorways. I believe that there are more motorways running through my constituency than through that of any other right hon. or hon. Member—the M4, M25 and M40. Each section is among the busiest on those respective motorways. The stretch of M4 is that between Heathrow and Maidenhead; the stretch of the M25 is that between two other motorways, where the traffic volume is already double the original estimate; and the stretch of the M40 is that between the M25 and High Wycombe.
It is hardly surprising that the Department now proposes to widen all three motorways to four lanes in each direction. I cannot see that it would be sensible to object, although that will cause my constituents considerable disruption, especially in respect of the M40.
I am concerned about the Department's further proposal for collector and distributor roads to run alongside the M25. That would add a further eight lanes—some have suggested that the number might even be 16—to the eight that already exist. The intrusion into the green belt and the damage to my constituents' interests thus caused would be wholly unacceptable.
§ Mr. Ian Taylor (Esher)I entirely endorse my hon. Friend's remarks about the M25. Collector and distributor roads are of great concern in my constituency also.
§ Mr. SmithI know that exactly the same damaging effects would be suffered by my hon. Friend's constituents.
Perhaps the most extreme example of the growing noise problem in my constituency is provided by the M40. When it opened 20 years ago, it was relatively quiet and perhaps even underused. With the extension of the M40 to Birmingham—which was not originally envisaged—traffic volumes have grown rapidly, as has the traffic mix. We now have many more heavy goods vehicles than we had only a few years ago and the noise is becoming intolerable.
The widening of the motorway offers my hon. Friend's Department an opportunity to examine further measures that can be introduced to deal with the noise, and I am grateful to my hon. Friend's predecessors for seeing representatives of the villages in my constituency and hearing at first hand their concerns and their ideas for tackling the problem.
How should we tackle noise from motorways and other roads? Basically, there can only be two possibilities; one can either treat the symptoms or remove the cause of any given problem. If there is a genuine choice between the two, I favour trying to eliminate the cause of a problem. That is the difficulty with measures such as earth bunds, special fences and tunnels. We have many of those. I am certainly not suggesting that I do not favour them. They 913 are absolutely essential and we shall need more of them in my constituency. But they do no more than treat the symptoms, and some of them are quite ineffective at surprisingly short distances from the carriageway. That is certainly true of fences. The sound hops over the top of the barrier and comes down within a relatively short distance on the other side. If one lives on the other side of a valley, a mile away from the motorway, the noise can come straight across and hit one in the face as it would if one were living only a few yards from the road.
I repeat that I am in favour of tacking the causes, and the main cause of noise on motorways is the interaction of tyres and road surface—although I dare say that there is some noise from engines. Anyone who has ever driven along a motorway and made the transition from a ribbed concrete surface to a black-top surface will know what I am talking about: there is an immediate reduction in the amount of noise thrown up from the road.
There is no doubt that some road surfaces are much noisier than others. The most noisy of all is concrete. I know that the Department does not accept that, but everyone I know believes it to be the case and common sense suggests to me that it is so. Ribbed concrete makes an awful lot of noise; black top makes less noise; and porous asphalt, which is the subject of the debate, makes considerably less noise than a conventional black-top surface.
Let me explain the advantages of porous asphalt, which I believe to be the answer to some of our noise problems. One advantage, which has nothing to do with noise, is that it would make an important contribution to improving road safety. The surface contains small holes so that, if it is raining hard, the water can go straight through, virtually eliminating spray. The Department has installed the two surfaces on opposite sides of a dual carriageway on the A38 in Derbyshire. I have seen a photograph of traffic travelling on both sides of that road in heavy rain. It is obvious that, on one side, the drivers can see practically nothing because of the amount of water that is being thrown up, while on the side with the porous asphalt surface the conditions are not too bad. That is an important fact. Surface water drains rapidly through the porous asphalt road surface.
From my point of view, the most important advantage of porous asphalt is that it significantly reduces noise, but it also has the important advantage of increasing skid resistance and reducing oncoming headlight dazzle in wet weather. I am sure that you, Madam Deputy Speaker, have driven along a motorway at night when it is raining hard and you will know that, after a time, one's eyes get very tired indeed. The porous asphalt surface reduces that damaging effect—another way in which it can contribute to improving road safety.
It is not as if the Department has not considered all those factors; it has. What concerns me, however, is the slow progress that it has made. As long ago as 1981—11 years ago—the Transport and Road Research Laboratory produced a report which said:
the noise from vehicles running on porous asphalt is less than that generated on conventional bituminous surfacings or on textured concrete surfacings. The average reductions in average vehicle noise were approximately 4 db(A) for light vehicles and 3 db(A) for heavy vehicles.That may not sound very much, but the amount of noise at any particular moment is significant. That is confirmed by what was stated later in this report. It says: 914These effects were approximately similar to halving the traffic flow or doubling the distance of the observer position from the traffic source. The noise benefits were not found to be dependent on the age of the surfacing. The low noise characteristics of the porous asphalt appeared related to the high acoustic absorption of the surfacing. Porous asphalt will lessen the incidence of 'splash' noise generated at the tyre-surface interface.All those Transport and Road Research Laboratory conclusions confirm what I have said. It will come as no surprise to you, Madam Deputy Speaker, to hear that this surface is now widely used in Europe and elsewhere. France, Netherlands and Belgium lay over 1 million tonnes of asphalt a year. Substantial quantities are also being laid in Hong Kong. As one would expect, they have been laid in areas near to large conurbations.Most regrettably, however, the position in the United Kingdom is different. No porous asphalt has been laid on a major trunk road or motorway for the past 20 years, apart from a trial section of 1.5 km laid on the A38 near Burton on Trent in 1984. The Department says that this material does not last, but the A38 road surface has lasted for eight years and I understand that it is still going strong. The cost is disputed. The Department says that this material costs more; the manufacturers say that it costs less. That may have something to do with cost benefit and value for money, but when it comes to value for money we need to take into account, on the benefits side of that equation, the massive noise advantages of laying this road surface.
I understand that the Department is also concerned about the overall strength of the surface. It may be that, due to the way that it is laid it is less strong at the surface, but we are talking only about a very thin layer at the top of a very deep section. If one cut a section through a motorway, one would find that its strength is to be found much lower down. The strength to take 38-tonne lorries is not found in the top three inches. We are debating only a very thin layer at the top of the section.
The Department also says that there are not sufficient quantities of the right kind of aggregate. I am advised, however, that that problem can be overcome. The Department also says that snow is a problem on this surface. That may be so, but we do not have snow all that frequently and, if we do, it should be dealt with quickly and not allowed to lie on the surface of the motorway. Normally it is cleared away quickly.
I have put forward my case as strongly as I can. I have seen a paper that was given as recently as 31 October 1991 to a BACMI seminar on this subject. The Department's representative, Mr. G. J. Bowskill, talked about pervious macadam and said:
This material offers great potential for locations where traffic noise or spray is likely to be a problem, but it does have drawbacks over its long term performance as identified by the research.The time has come to have a few more trials with this material. There ought to be a few more trial areas, and I should like one to be located in my constituency.The environmental consequences of road surfaces need to be taken more into account than they have in the past. I understand that we want to achieve the most cost-effective road construction. That must be the Department's primary objective and there must be good opportunities for achieving it at the moment, because tenders must be coming in well below previous estimates.
There is no reason why we should not have a road surface that will be acceptable to my constituents. I 915 understand that the TRRL has now reported to the Department the successful results of the major trial of porous asphalt on the A38 Burton bypass in Staffordshire. BACMI suggests that there is
little reason for the DTp not to adopt Porous Asphalt and issue the guidance note"—which has been promised—allowing greater use of the material.That is what I want to see—greater use of the material, because the way to tackle motorway noise is through its cause. I am sure that we shall have to put up with noise and will never eliminate it. The problem will grow, so we need to tackle its cause and the symptoms. This would be a cost-effective way of doing so.
§ The Minister for Roads and Traffic (Mr. Kenneth Carlisle)I congratulate my hon. Friend the Member for Beaconsfield (Mr. Smith) on securing this debate and on his interesting choice of topic. I shall deal with its wider applications and implications later.
We are all concerned about reducing the adverse effects of road traffic on local residents. At the same time, we can agree that we all want to keep traffic moving smoothly on the road network. It is worth recording that although the trunk road and motorway network represents only 4 per cent. of the overall network, it still carries about 32 per cent. of all traffic and more than half of all commercial traffic. The reduction of noise and spray is therefore a valuable goal which I wish to pursue. I respect the aims of my hon. Friend in wishing to protect his constituents from the noise that those major roads around and through his constituency create.
Porous asphalt is an open textured road surfacing material that permits surface water to drain through it rather than to remain on the surface. It was originally developed to reduce spray in wet weather, to improve visibility. As we discussed in the previous debate, the cause of accidents is often complex and there is little evidence to show that accidents are directly related to spray. Any spray reduction in marginal and wet weather improves drivers' visibility. Although that may appear to contribute to safety, we are not certain whether it does, because poor visibility in heavy rain also reduces vehicle speeds on conventional surfaces. In contrast, on porous asphalt drivers may travel faster.
Although initially spray is dramatically reduced by the use of porous asphalt, that benefit is reduced as the structure of the asphalt becomes clogged, preventing the rain from seeping through it. Consequently, any accident benefits from the use of porous asphalt are likely to be short lived.
By far the most important benefit of porous asphalt—I agree with my hon. Friend about this—was discovered during testing trials, when its ability to reduce noise by 4dB in dry conditions, and even more in wet, became apparent. As my hon. Friend said, that is the equivalent of halving the traffic flow and is achieved by noise on heavily used fast roads being absorbed into the pores of the material. This absorption of noise is only slightly reduced by aging and salting, unlike the spray reduction characteristic.
On the surface, if my hon. Friend will forgive the pun, porous asphalt seems to be a wonder mix. Regrettably, it has some disadvantages that we should consider in a 916 balanced debate. It simply is not as durable as conventional surfaces and would therefore need more frequent maintenance. One particular problem is that once the surface starts to deteriorate, the rate of decline will be more rapid than with ordinary surfaces. That not only increases the cost of porous asphalt but results in more of those dreaded traffic cones, which are so hated by motorists and my hon. Friend's constituents. Porous asphalt has the disadvantage of being significantly more expensive and would force us to repair our motorways more frequently. The structural strength of the material is not quite as robust as conventional surfaces and, to compensate for that, the thickness of the material needs to be increased, pushing the costs up still further.
I am pleased to say, however, that our own research, together with that of the industry, is tackling this problem by trialling variations in the constituents and mix of materials. We hope that in a few years we shall have material which approaches the same life as conventional surfaces. Then things could be very different.
As part of our effort to improve road safety, we have had a policy since 1988 of maintaining a minimum level of skidding resistance for our roads. In simple terms, skidding resistance is the roughness of the road necessary to stop vehicles slipping. This is proving very successful and as a result we have seen a reduction in accidents of about 6 per cent. To achieve this level of skidding resistance, we roll into the surface a high-quality aggregate. It is not possible simply to roll aggregates into porous asphalt—they have to be bound into the whole structure, significantly increasing the amount used.
Aggregates with high skid resistance are in short supply in the United Kingdom and are therefore more expensive. Increased use of those aggregates would also mean more quarrying in environmentally sensitive areas and more haulage over greater distances. My hon. Friend disagrees with me about the availability of the material, but perhaps we can explore the issue. He also said today that this material is used in Europe and that we are being overcautious, but, equally, we must be cautious in making direct comparisons. European skidding resistance requirements are very much lower than in Britain and thus permit the use, on the continent, of cheaper and more plentiful aggregates. I am not prepared to compromise our safety requirements.
When weighing up the pros and cons of porous asphalt, two other aspects need to be considered. The first is winter maintenance. Because of its physical characteristics, ice tends to form earlier and clear later than with a conventional surface. I am told that that is because the cold is not conducted away so rapidly and when, as a result salt is applied, some will be lost in the open pores. That means that the amount of salt used and the frequency of spreading has to be increased, both of which cost more.
We also now know that salt can cause damage to bridges and structures as well as to adjacent vegetation. More salt used to de-ice the road means more saline solution running off into the surrounding areas, causing further environmental damage. Therefore, we all have an interest in reducing the total volume of salt which we put on our roads and which then spreads around the countryside.
Our trials have also shown that porous asphalt surfaces break up more easily where heavy braking and turning takes place and for the material to function effectively, the 917 integrity of the drainage paths through the material must be maintained. That cannot be guaranteed at present, especially in urban areas.
To sum up, we have in porous asphalt a material which provides significant noise reduction benefits as well as some spray reduction. At the same time, it does have some drawbacks—notably, its reduced strength and durability, greater cost initially and for future structural maintenance, and increased winter maintenance. There are also some environmental drawbacks which need to be balanced against the possible environmental benefits. It is a balance which I must strike when considering when it is sensible to use this product.
I am satisfied that we now have a specification for porous asphalt, which will allow its use for some trunk road and motorway applications, but only where conditions are regarded as suitable and its use is cost effective. It is technically not yet suitable for universal application—for instance, where heavy braking or turning occurs, in urban situations where statutory undertakers need to have frequent access to their equipment and where there are heavy concentrations of commercial vehicles.
Even where the conditions are acceptable, it may still not be cost effective to use. We must remember that the increased costs will have to be found from the Department's existing budget and it will mean less to be spent on new construction and maintenance elsewhere.
918 I am keen to use the material in the right place and I intend to allow a limited use of porous asphalt on trunk roads and motorways where the benefits can be shown to outweigh the drawbacks. My Department has produced a draft specification and advice note giving guidance on its use and I am asking it to proceed towards early notification to the European Commission for the necessary consultation in accordance with the notification directive. We will, at the same time, invite comments from the United Kingdom industry.
Once those procedures are cleared, we can proceed to introduce porous asphalt on to our roads. This will be limited but will be a step in the right direction.
I am grateful to my hon. Friend the Member for Beaconsfield for requesting a debate on this interesting subject. We all have a great interest in trying to reduce noise on our motorway system. In my three weeks in the Department I have come to the conclusion that we must try to do better in that regard, because noise is one of the great pollutants of people's lives. The problem can be seen not only in my hon. Friend's constituency but further up the M40 towards Birmingham, so he has raised a very useful subject.
I hope that we can press forward with our trials and find a way to make our motorways less noisy.
Question put and agreed to.
Adjourned accordingly at four minutes to Three o'clock.