Impermeability
When it rains, the impermeability of hard surfacing causes more rain water to run-off. This causes greater fluctuations in amount of water going into the roadside storm drains and from there to local streams and rivers. This in turn leads to:
1. An increased risk of flooding, especially flash flooding.
2. Erosion and damage to riverbanks and hence to their habitats.
3. Increased pressure on roadside storm drains and the drains system.
4. In some areas, particularly London, this leads to increased pressure on sewers, even leading to forced release of sewerage into rivers, as occurred in the River Thames in August 2004.
5. Localised flooding of streets, pavements and nearby properties.
Pollution
As it runs off, rain water picks up oil and heavy metals from the hard surfaces beside and close to roads, plus pesticides, herbicides and other chemicals used in gardens. This leads to:
6. More pollution of local watercourses, which has a range of detrimental effects on water quality and on wildlife.
7. Polluted rivers and streams, which are unattractive and therefore less used by people for leisure activities, leading in turn to neglected areas which are more prone to vandalism - a downward spiral of deterioration, vandalism and hostility sets in.
Rainwater
More run-off means less rainwater percolating through the soil.
8. This means less water purification and removal of pollutants from ground water by soil percolation processes.
9. It also means soil drying out, leading to greater risk of building subsidence.
Heat, Noise and Dust
Hard surfaces have several other characteristics which create problems.
10. They absorb more solar heat, so contributing to making built up areas hotter (the 'heat island' effect). Hotter towns and cities affect people's health, as demonstrated in Paris in Summer 2004.
11. To keep cool, people use more air conditioning, which uses more energy, often derived from fossil fuels.
12. Both the heat island effect and the increased use of fossil fuels contribute to global warming, a very serious concern.
13. Hard surfaces absorb less noise, which means more noise from traffic and other sources, especially for people living at ground floor level.
14. Hard surfaces don't absorb dust. This means more dust in the atmosphere, leading to increased air pollution (particulates).
15. Hard surfaces don't absorb dirt and spills, leading to a dirtier, less appealing environment for people to live in.
Parking
Hard surfacing front gardens for parking leads to a further set of problems.
16. More pavement crossovers (kerb drops) make pavements uneven and corrugated, and walking becomes more difficult, especially for people who have difficulty walking, for small children and for people pushing buggies or driving mobility scooters. It is also more difficult for two people to walk and talk together side by side.
17. Vehicles being driven across and reversed across the pavement creates risks to pedestrians, especially children.
18. Parked vehicles overhanging the pavement means less space on the pavement for pedestrians.
19. Vehicles parked in front gardens are higher and more solid than garden vegetation, which means pedestrians are less able to see around them. This makes for a more dangerous pedestrian environment, especially for children, when we are all being encouraged to walk more.
20. Using front gardens for parking often creates a net gain in car parking spaces, which therefore contributes to generating greater volumes of traffic - contrary to Government policies to reduce traffic.
Crossovers
Increased numbers of pavement crossovers (dropped kerbs) to allow front garden parking causes a corresponding reduction in the number of on-street parking spaces available. That's because people generally don't park in front of a pavement crossover, thus effectively reserving that section of the road for the sole use of the dwelling with the crossover.
21. This leads to more pressure for parking spaces, so more people apply for pavement crossovers to enable them to park in their front gardens, and so on, leading to a domino effect as more front gardens converted to parking.
22. 'Parking wars' cause rows between neighbours and damage neighbourhood relations.
23. Less on street parking reduces the control that the highways authorities have over parking.
24. Fewer cars parked on the road creates a wider road with improved visibility, which encourages traffic to speed, thereby creating a more dangerous environment for residents, especially children, and pedestrians.
Plants, Trees & Wildlife
Hard surfacing of front gardens often means that most or all of the garden's vegetation is removed. This creates yet a further set of problems.
25. Fewer plants means less carbon dioxide absorption, therefore more contribution to global warming, the effects of which are becoming increasingly evident and alarming.
26. Loss of shade created by plants and the cooling effect of plants' evapo-transpiration leads to a hotter local environment and so contributes to 'heat islands' (see numbers 10-12 above). Under the latest climate change forecasts, our cities may become dangerously hot in summer. Vegetation will help to counter this.
27. There are fewer habitats for wildlife (both above and below ground level): front gardens, though often small compared with back gardens, can nevertheless make a difference to the amount of wildlife an area can support. The decline in sparrows has been linked to paving front gardens.
28. Fewer plants and less animal life leads to less biodiversity.
29. Removing or reducing the garden also means less or no gardening activity. Gardening at the front of the dwelling provides opportunities to chat to and get to know neighbours and passers by informally. Hard surfacing is a significant factor in reducing 'community cohesion'.
30. The removal of grass verges to accommodate pavement crossovers also has an adverse effect on plant and animal life, contributes to global warming and increases run-off etc. by replacing with hard surfacing, in the same way as described above.
31. Replacing grass verges with hard surfacing also changes the character of a road and leads to loss of aesthetic appeal (see below).
32. When street trees are removed to accommodate pavement crossovers, there are fewer trees to absorb pollutants, leading to more air pollution and a range of damaging effects on people's health.
33. Fewer trees also means loss of habitat for birds, insects etc., so there are fewer birds in the vicinity.
34. Fewer trees also means a more stressful, tense neighbourhood. It is well established that trees have a calming effect on neighbourhoods.
Character
Hard surfacing of front gardens changes the aesthetics and character of roads and neighbourhoods.
35. Many people are upset by the changed appearance and aesthetic appeal of their neighbourhood once front gardens are hard surfaced, and soft green areas and trees are replaced by cars and hard, often unattractive surfaces.
36. The visual appearance, attractiveness and entire character of a neighbourhood are altered when front gardens are hard surfaced, and the sense of balance and values that derive from front gardens being in keeping with the houses that they front, is lost. Instead, the hard surfaced jars with the traditional architecture.
37. This in turn leads to changing street characteristics, unhappy residents and a reduction in community cohesion.
38. In addition, it is clear that, when most or all of the front gardens in the street have been hard surfaced., house prices fall, reflecting the less attractive environment.
Hedges and Fencing
The removal of boundary structures (hedges, fencing etc.), common when front gardens are hard surfaced for parking, is also problematic.
39. There are fewer barriers to wind, leading to higher levels of dust and hence particulate air pollution.
40. The loss of boundaries and demarcation can cause tensions between neighbours.
41. Removing the barrier between the pavement and the dwelling increases the risk of trespass, graffiti and vandalism.
Sources
Finally, the sourcing of hard surfacing materials used can cause problems.