18 July 2014
Phil Jones discusses why approaches have changed when planning for parking capacity
Car parking is one of the most difficult aspects of any development to get right. It touches on many critical issues: the layout and structure of sites and individual buildings, the overall density, its marketability, costs, revenues and viability. Development values can be reduced by providing either too little or too much car parking – what is the right approach?
Planning policies on car parking have swung backwards and forwards over recent years. Prior to the mid-1990s, most standards set out minimum levels on the basis that under-provision led to overspill on street causing road safety and congestion problems.
Car parking is one of the most difficult aspects of any development to get right. It touches on many critical issues
The move towards using planning policy as a means to reduce car use began in 1994 when PPG13: Transport set the bold objective of "reducing reliance on the private car". At that time, authorities were instructed to "set… a range of maximum and operational minimum amounts of parking for broad classes of development and location", although critically they should "not require developers to provide more spaces than they themselves wish".
In 2001, a revised version of PPG13 took this further by stating that authorities "should set maximum levels of parking for broad classes of development", and giving overall national non-residential maximum standards to prevent authorities competing for development by setting lax values. The maximum car parking ratios (in terms of gross floor area) in Annex D included:
- food retail: one space per 14sqm
- non-food retail: one space per 20sqm
- B1 including offices: one space per 30sqm.
Many authorities still use these figures in their standards.
At that time, residential car parking standards were set in the 2000 version of PPG3: Housing, which included the much-misunderstood phrase:
"Car parking standards that result, on average, in development with more than 1.5 off-street car parking spaces per dwelling are unlikely to reflect the government's emphasis on securing sustainable
This was widely interpreted as setting an upper limit of 1.5 spaces on any dwelling, even though this is far too little for some types of housing in some places.
Not surprisingly, when CABE carried out a series of housing quality audits in the mid-1990s, 'insufficient car parking' was one of the most common complaints of new occupiers. The reports also highlighted the over-use of rear parking courts, which blight the space between houses, and poorly-planned streets that resulted in on-footway parking.
The pendulum began to swing back in the late 2000s towards a more flexible approach to car parking standards, largely driven by concerns of under-provision and the potential adverse economic consequences of restricting parking.
Today, the National Planning Policy Framework puts the setting of standards entirely within the competence of local authorities, which should take the following into account (paragraph 39):
- the accessibility of the development
- the type, mix and use of development
- the availability of and opportunities for public transport
- local car ownership levels
- an overall need to reduce the use of high-emission vehicles.
This is all sensible advice, and clearly there is a need for authorities to develop evidence-based standards. But this is not always done.
Patterns of use
When considering car parking standards and the appropriate level of provision, it is important to distinguish between 'destination' (e.g. employment or retail development) and 'origin' (i.e. residential) car parking. Essentially, the former depends on car use, the latter on car ownership. Many authorities have now moved across to minimum car parking standards for residential development, while retaining maximum standards for other land uses.
For employment development, car parking has been shown to be the major determinant of travel mode choice – the biggest stick in most Travel Plans. Few people choose to drive into central London, or even Oxford, because car parking is limited and expensive. For employees, the journey to work is non-discretionary, and so restricting car parking helps to generate demand for non-car travel options, such as Park and Ride sites. Where alternatives are not available, however, parking at old PPG13 levels can lead to considerable excess demand – often seen at edge of town business parks.
For employment development, car parking has been shown to be the major determinant of travel mode choice
Retail and leisure developments generate mainly discretionary trips, and so if travel by car is made too difficult, people may simply go elsewhere. Retail and leisure developers set a high value on achieving acceptable levels of car parking and will generally be unwilling to see any restriction. As noted above, the government (not to mention retail consultant Mary Portas) believe that providing plentiful free or cheap car parking is the key to regenerating high streets – but is it that simple? Providing more destination car parking will result in higher volumes of traffic, which tends to make centres less attractive. Do people visit shopping malls only because of the free parking, or is the absence of traffic when they reach the shops also a factor?
Some developers may therefore wish to push for higher levels of car parking on commercial sites, but this would need to be taken into account in the Transport Assessment, which could then result in a greater requirement for off-site highway improvements. Extensive on-site car parking is also land hungry – 1 ha of land accommodates about 400 cars. As in all things, a balance has to be struck.
Simple car parking ratios, like those previously given in PPG13, are the norm, but in reality parking demand results from the interplay of a number of factors:
- overall travel demand
- car driver mode share
- duration of stay
- degree of allocation between different land uses/occupiers.
Where necessary, more detailed assessments of parking demand can be prepared to challenge local authority standards.
Ownership and use
Looking at residential development, research carried out by Phil Jones Associates (PJA) in the mid-2000s for the government, based on Census data, found that residential car parking demand varies considerably (see Table 1).
|Location||Rural areas higher demand than urban|
|Dwelling type||Houses higher demand than flats (of same size)|
|Dwelling size||More rooms/bedrooms, more cars|
|Tenure||Owner occupied higher than rented|
The research found that there is a strong desire to own cars if the household could afford it, and that under-provision of parking is ineffective in limiting car ownership, unless local on-street parking is limited or tightly controlled. This research partly led to the change to minimum standards.
Essex County Council was one of the first authorities to make this change in 2009, setting a simple 1 space/1 bed, 2 spaces/2+ beds, plus visitor spaces. Garages are not included, because research has shown they are seldom used for car parking.
Other authorities have taken a more evidence-based approach to the problem. In 2010, PJA undertook research for Dudley Metropolitan Borough Council which resulted in standards that reflected observed car ownership levels while allowing for growth. The UK is only mid-table when it comes to owning cars and so it is reasonable to assume that car ownership may rise, at least in relatively unconstrained areas.
In the Dudley research an annual growth rate in car ownership (for owner-occupied houses) of 1.2% was assumed, based on surveys carried out in 2010, and with a design horizon of 2025 an overall increase of 20% in parking demand formed the basis of the new standards.
Since that research was carried out, car ownership data from the 2011 Census allows initial assessments of growth over the past 10 years. This revealed that in fact, in Dudley the actual increase in car ownership for owner-occupied houses has been less than assumed, at 0.7% pa, but clearly growth is still occurring.
The equivalent figure for England is similar at 0.8% pa, but there are local variations. Birmingham has seen 1% growth, while Southwark in inner London has seen a decline of 0.5%.
As noted by Essex, however, it is not just the number of spaces but their design that is important. Rear parking courts, reviled by CABE, are not just inefficient in space terms; they are often underused by residents, who prefer to keep their car in sight at the front or side of the property.
The research also highlighted the value of shared parking areas, for use not only by visitors but by households with high numbers of cars. The most efficient way of providing these may be wider streets with clearly defined bays to prevent parking on footways.
However, just because most households aspire to own a car, increasing car ownership does not necessarily lead to increased car use. Traffic growth has generally been below Department for Transport forecasts over recent years, particularly in urban areas. Traffic in London peaked in the 1990s and has been declining since, mainly due to improved public transport and restrictions on destination car parking – although anecdotally there may be a concern that it may be impossible to find a place to park on the return to home.
In conclusion, getting parking right is complex. Changes in central policy may have left local authorities confused about whether to use parking as a tool to reduce car travel, or to prevent on-street congestion occuring. Developers need to understand the options, decide what is right for them and build a robust case, based on sound data.
Phil Jones is Managing Director at Phil Jones Associates
Related competencies include: Planning