09.1 Natural traffic calming
The principle of traffic calming is to
require drivers to drive slowly and respect other road users,
notably pedestrians. This can be done by legally enforced
regulation often involving signs and lines. Natural traffic
calming uses physical restrictions to reduce forward visibility
or cause drivers to reduce speed in order to turn sharply
or negotiate a stretch of narrow road. Parked
cars at right angles to the road, or trees in the road all help
reduce speed and can be incorporated seamlessly into the surrounding
built form to appear to be a natural part of the street scene.
09.2 Parking techniques: Yellow
lines
Width of yellow lines
Yellow lines may be
100 mm wide (4 inches) or 50 mm wide (2 inches). 
Even though chapter 5 of the Traffic Signs Manual
states that 50 mm wide lines may be used in environmentally sensitive
areas, this is only partially true. The Manual is advisory and
it is for the local Traffic Authority to decide which width is
appropriate.
Under the statutory Traffic Signs Regulations and
General Directions (TSRGD), 50 mm wide lines may be used anywhere.Therefore
the Traffic Authority can lawfully apply the narrower 50 mm yellow
lines, rather than the 100 mm wide lines, where ever it wishes.
Precise colour of yellow lines
A paler yellow,
known as primrose, is less garish than the normal yellow colour.
Although the Traffic Sign Manual recommends its use only in environmentally
sensitive areas, it is acceptable as yellow under the TSRGD.
The Traffic Authority can lawfully apply the subtle primrose
colour rather than the more vivid yellow, where ever it wishes.
Alternative to yellow lines
Where a restrictive parking zone
is designated, yellow lines may be omitted and replaced with
signs. In these zones parking is only permitted where bays are
marked.
