愛爾蘭喺呢方面都一樣幾先進下
https://www.housing.gov.ie/sites/default/files/migrated-files/en/Publications/DevelopmentandHousing/Planning/FileDownLoad,32669,en.pdf#page=62
There are a number of advantages to
more permeable networks in regard to the
management of traffi c and vehicle speeds
such as:
• Drivers are more likely to maintain lower
speeds over shorter distances than over
longer ones. As drivers are able to access
individual properties more directly from
Access/Link streets (where speeds are
more moderate) they are more likely to
comply with lower speed limits on Local
streets (see Figure 3.21).
• Permeable layouts provide more frequent
junctions which have a traffi c-calming
effect as drivers slow and show greater
levels of caution.7
• Increasing access to neighbourhood cells
can result in the more equitable distribution
of traffi c and the impacts of congestion
as it is no longer concentrated on a few
select junctions or local access streets (see
Section 3.4.2 Traffi c Congestion) and noise
and air pollution (see Section 3.4.5 Noise
and Air Pollution).
• The value of place can also be improved
as slower moving traffi c has less impact on
the surrounding environment (see Section
3.4.5 Noise and Air Pollution).
• Frequent entrances to a neighbourhood
cell can reduce the size of individual
junctions and streets. This will reduce
the potential for severance between
communities and increase pedestrian/
cyclist mobility as streets/junctions are
more compact and easier to navigate.
Designers may be concerned that more
permeable street layouts will result in a
higher rate of collisions. However, research
has shown that there is no signifi cant
difference in the collision risk attributable
to more permeable street layouts in urban
areas and that more frequent and less busy
junctions need not lead to higher numbers of
accidents.
[...]
Filtered Permeability Networks, which restrict
universal permeability, may be applied
where designers are seeking to prioritise the
movement of more sustainable modes (i.e.
pedestrians, cyclists and public transport) over
private vehicles. For example bus gates and
other measures, may also be used to prioritise
bus movements, particularly in Centres (see
Section 3.4.3 Bus Services).
The limited use of
vehicular cul-de-sacs may be considered in
Neighbourhoods and Suburbs where there is a
particular concern regarding through traffic.
The use of vehicular cul-de-sacs to enforce
Filtered Permeability networks should be
approached with caution. Their overuse can
result in many of the negatives associated
with Dendritic networks being replicated.
Additional design measures should be applied
to ensure that pedestrian and cycle links are
not perceived as ‘anti social spaces’. Links
should maintain clear sight lines and be
overlooked by development (see Figure 3.23).
Within existing networks, pressure is often
applied from local communities to create
vehicular cul-de-sacs. Designers should
approach such requests with caution, as street
closures will often simply shift the problem
elsewhere.
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