Phil Jones Associates - Frequently asked questions
On this page
we give the answers to some technical questions we are often asked by clients.
If you have any suggestions of topics that you would like to see covered on
this page, please email us at admin@philjonesassociates.co.uk
What is a Home Zone?
A Home Zone
is a residential street or group of streets, designed primarily to meet the
interests of the local community, whether on foot, cycling, or in a car, enabling
the street to operate primarily as a space for social use. Encouraging children's
play is an important aim of many home zone schemes. Home Zones have a very
good safety record, but are not primarily designed as road safety schemes.
When Home Zones are created from existing streets, community involvement is vital to ensure that the scheme meets local needs. The process of designing the home zone with the participation of local people in itself strengthens the community. Home Zones are also encouraged by the UK Government as part of new residential areas.
Although it is not possible for prospective residents in new developments to be involved in the design of new streets, steps can be taken to involve them in their maintenance and management. Residents will also need to be consulted by the local Traffic Authority on the precise uses that can take place on the street (specified through a 'Use Order') and the appropriate speed of traffic on the street (specified through a 'Speed Order') before the Home Zone can be legally designated and signed.
Home Zones often
involved the use of shared surfaces, where the street is not strongly divided
into exclusive pedestrian and traffic areas. Concerns have been expressed
over the inability of blind and partially sighted people to use shared space
streets. Providing a clear route for pedestrians that is kept free of traffic,
by using street furniture for example, is one way of meeting the needs of
the visually-impaired.
Home Zones often include features such as benches, tables and play equipment
to encourage social interaction. Street trees and areas of planting, ideally
maintained by residents, will often feature. On-street parking also forms
part of the layout in most schemes.
The
Home Zone sign in use at South Lynn Millennium Village
Traffic speeds
are kept low - with a typical target speed being around 20 km/h (10-15 mph)
- through the overall design of the street and features such as sharp changes
of direction for traffic and narrowings where only one motor vehicle can pass
at a time. Traditional traffic calming features such as road humps can also
be used, but should be integrated into the design rather than being added
as an engineered afterthought.
PJA has worked on home zone schemes in both existing streets – such
as at Morice Town, Plymouth – and on many new build schemes including
projects at Kings Lynn, Croydon, Crawley, Telford, Redditch and Ashford.
Planted
areas at South Lynn Millennium Village
Where are the reduced visibility requirements, as set out in Manual for Streets, applicable?
Manual for Streets, published by Department for Transport in May 2007, set
revised visibility requirements for urban streets and junctions, well below
those given in previous advice contained in the now-withdrawn Design Bulletin
32.
Some highway authorities are concerned that adopting these revised values
will have adverse implications for road safety.
The recommendations given in Manual for Streets are based on research
carried out by Transport Research Laboratory, as reported in research
report TRL661. [Click to download]. An important
principle established by the research is that reduced forward visibility
typically leads to lower vehicle speeds. Reducing sight lines from 120
metres to just 20 metres was shown to reduce speeds by around 20 mph.
No positive relationship was found between increased visibility and
road safety. The analysis of accident data confirmed the fact that higher
speeds increases the likelihood of injury and its severity.
This research turns on its head the notion of a ‘design speed’, whereby street geometry is based on the idea that drivers are mere robots who will choose to travel at a particular speed regardless of the environment; and that geometry must be provided that enables them to behave in this way.
Previous advice on stopping distances/visibility in DB32 made generous assumptions for the time required for drivers to react to a hazard (2 seconds) and the safe deceleration rate for the vehicle (0.25g). The TRL research revealed that the apparent safety benefit of the long vision splays that resulted from applying these values is eroded by drivers choosing to travel above the design speed.
MfS recommends lower visibility requirements, based on a driver reaction time of 1.5 seconds and a deceleration rate of 0.45g, both of which are in line with values used in other countries. The shorter reaction time is recommended for urban areas in general, where drivers are likely to be more alert to the presence other road users and to hazards. The deceleration value of 0.45g is consistent with firm but not emergency braking.
Notwithstanding the fact that the main thrust
of MfS deals with residential areas, these values are recommended throughout
urban areas. Inspectors at planning appeals appear to be upholding this
important principle. (See Appeal Ref: APP/P4225/A/07/2040756/NWF Site of
Coral Mill, Shaw Road, Newhey, Rochdale, OL16 4SQ – Decision published
27 September 2007).
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