Assignment II
(1a.)
Discuss the control of road hierarchy in the design of a low-income residential area.
(1b.)
What role does the road hierarchy play in terms of traffic movement within the sited area?
Introduction
This assignment explains the road
classifications and hierarchies. The road categories try to define their
design, adoption and management standards, regardless of which local authority
is responsible for any particular road. Basically a road or route hierarchy
describes a ranking of some or all public roads and routes in a chosen area to
manage route space for appropriate traffic uses - reflecting economic, social
and environmental needs. The hierarchy differs from ordinary
road-classification as it defines road and route purposes rather then
pre-existing route standards. Routes are then managed and developed to suite
their "route-purpose"
There are a number of reasons why consider a
road hierarchy. These include
•to obtain the best use of the existing network
•to ensure each type of traffic is using the
most appropriate route
•to minimise risk to users and to the natural
and built environment
•to ensure better management, maintenance
regimes and design policies
•to ensure funding for routes is targeted
appropriately
•to offer network users a choice for how they
travel
Body
Hierarchy development encompasses many elements
of work associated with route planning and development including signage,
maintenance, route surfacing, number of users, and potential destination of the
route. You must consider these factors when establishing your hierarchy.
A hierarchy is established by:
Developing different categories of route - these
categories will be determined by the primary journey purposes untaken, the
standard of the route surface, the potential destinations on the route and the
size of the route
•developing detailed criteria in order to assign
routes to the hierarchy - as well as determining the types of traffic to use
the route this should also include details about management and maintenance of
the routes
•assigning routes to the hierarchy
•assessing "problem" areas - it must
be recognised that not all routes will fit exactly into each category and in
some cases you may have to consider adding physical measures to a route in
order to address user safety.
One should ensure that an after monitoring
programme is included within your business plan for developing a hierarchy and
that the hierarchy is reviewed regularly
The Principles used in Creating the Road
Hierarchy are that road hierarchy creates the basis for a single road
management system. Provides roads that perform a similar function with
comparable target standards throughout the low-income residential area.
It also
facilities the strategic allocation of road funding, Maximises transport
efficiency, provides appropriate road safety design for the numbers and mix of
vehicles; and Provides consistency of road travel.
Demand assessment information in route hierarchy
development
Element of Demand
Vehicle and user flows on each route
Assessment Reasons for considering within a
route hierarchy
As a practitioner you need to know how many
users are using your network and which routes in particular they are using.
This will enable you to determine how to allocate routes in the hierarchy and
also for considering maintenance and management regimes.
Origin and destination of users
Here you need to consider the information above
but in addition consider where routes lead to and where people actually want to
go. This should also help with allocating routes to the hierarchy.
The mode or means of travel - walker, cyclist,
horse rider
Different users have different requirements and
your routes may need to be adapted or classified in the hierarchy to reflect
the types of users on each route. e.g. if you have one route primarily used by
equestrians you may need different surfacing.
Purpose of the journey
Linked to origin/destination as above it is
essential that you categorise routes to ensure that they lead where people want
to go. As with on road routes there maybe a choice of routes to use but
ultimately it will be the purpose of the journey, which will determine route
choice.
Problems on the network
All route networks will have areas where there
are problems of hotspots. Within your hierarchy you need to consider
maintenance and upgrade issues, information about problem areas in connection
with user flows and origin/destination information will enable you to
prioritise work within the hierarchy.
A future forecast for overall development of
your hierarchy and your Greenways project is starting for the resources and
network available today.
In order to ensure continued use of the network
you must consider changes or additions to the route and the hierarchy. Future
forecasts will enable you to predict trends and issues, which will need to be
included within your hierarchy and project plan
The classification of roads is dependent on
their function that they are expected to perform within the residential area
and in order to ensure that the function is
performed efficiently, certain traffic
management measures may be taken.
The main characteristics of these roads are as
follows: -
The hierarchy of roads adopted by the Council,
the primary journey purposes and functions which they should fulfill, and the
type of standards, improvements and character appropriate for them are
summarised below:
Primary Routes
These are roads, which form the links between
the most important traffic origins and destinations. Primary routes consist of
motorways, trunk roads and the most important County 'A' roads. It would not be
normal for existing or new developments to have direct access on to a primary
route and such limitations will be rigorously applied. The Urban Council will
encourage through traffic to use Primary Routes; Improvements to Primary Routes
will be appropriate where they bring about environmental benefits to
communities by the removal of through traffic or rat running. Capacity
improvements to reduce congestion may be appropriate in some cases.
Each situation will be assessed on its merits
The Trunk Roads are major highways that are
crucial to the functioning of industry, commerce and society. They are the key
links supporting the future economic development. They carry large numbers of
heavy freight vehicles and passenger vehicles. These roads facilitate
inter-regional freight movement, inter-regional passenger vehicle movement and
commercial interaction.
The Trunk Roads connect major population
centres, major seaports, major airports and major industrial locations.
Management of Trunk Roads is usually by the
government through the ministry of roads.
The Trunk Road Targets
•Sealed surface
• Wide lanes, sealed shoulder and at least a
1.0m sealed shoulder and a 1.0m unsealed shoulder, Overtaking lanes. Dual
carriageways where warranted •Town bypasses where economically justified
•High performance road markings including raised
reflective markings. Road standard and geometry permitting high speed.
Where appropriate, junctions designed for high
productivity vehicles and truck parking areas along the road. Limited property access directly onto the
road
However, it will still be appropriate for a
hierarchy of the roads to be developed in urban areas so that roads can be
developed to best fulfill their most appropriate function. As the Urban Council
does not wish to encourage car use in urban areas it will not improve urban
roads solely for capacity reasons. Any urban road improvement will need to
satisfy one or more of the following:
Have substantial environmental benefits such as
enabling traffic to be taken out of a town centre, which far outweighed any
environmental non-benefit;
Have the primary aim of reducing road accidents;
Be necessary to enable urban redevelopment or
urban regeneration proposals to proceed.
Urban Main Distributor Roads
These are the main roads, which distribute
traffic within towns, around towns’ centres and link town centres and main
industrial areas to the Primary Route Network. Urban Main Distributor roads
will be designated 'A' roads with white backed signs. New access onto these
routes would not normally be allowed.
The Council will: manage traffic arrangements to
encourage main flows onto the main distributor roads; restrict parking along
them; develop bus priority measures along them where appropriate; make adequate
provision for the safe crossing of pedestrians and cyclists.
Urban Secondary Distributor Roads
These roads will connect important urban
neighbourhoods to each other and to the Main Distributor roads, and form the
distributor routes through large residential areas. Secondary Distributor roads
will normally be designated 'B' roads and it is appropriate for these to be bus
routes.
The Council will: only carry out improvements to
these roads specifically aimed at making them safer; improve conditions along
them for cyclists and pedestrians;
where appropriate implement bus priority
measures.
Primary Distributors carry longer distance
traffic to, from and across the urban area with some connections with the state
or national road network running between urban areas. Vehicle volumes on these
roads are high and these roads operate as truck routes and carry heavy goods
vehicles. The level of service for traffic flow in these streets should
encourage rather than discourage traffic
from using them.
Characteristics of primary distributors include
the following
No frontage access for residential uses and
access limited for commercial
developments.
Provision of adequate road reserve for any future expansions.
No right
turns unless at controlled junction or grade separated intersections.
Pedestrian access ways/crossings to and across roads should be
grade-separated
or
controlled.
Provision of separate cycles routes with crossings at designated
traffic light
intersections.
Consideration should be made for bus routes and separate bus bays
to be allocated.
No
parking allowed on road.
District Distributors (A & B)
The function of these roads is to carry traffic
between industrial, commercial and
residential areas within the City. These roads
run between land-use cells and
generally not through them, forming a grid,
which would ideally be spaced around 1.5 kilometres apart. There are two types
of district distributors that are type A and Type B. Heavy goods vehicles would
be likely to use these roads. The determination as to whether these streets are
Type A or Type B would depend on the existence of a Primary Distributor within
two to three kilometres generally in a
parallel direction. The road is likely to
perform a Type A function if there are no
Primary Distributors within the above spacing
and a Type B function if such a road does exist. This type of distributor
should meet certain standards or expectations some of which are for district
Distributor A
Residential frontage access is generally not
supported.
Commercial/Industrial access to be limited and
access through service
roads/ROW and combined access ways to be
encouraged.
Pedestrian crossing to be considered on safety
and functional aspect of
carriageway at controlled crossings and at bus
stops.
Carriageway to be either divided or undivided
with at least 4 lanes being
provided.
Desirable speed limits to be 60-70 kmh.
Consideration should be made for bus routes and
separate bus bays to be allocated.
Generally no parking with clearways as
necessary.
Bicycle lanes to be provided parallel to street
with wider kerbside lanes.
Right Turns into District Distributor A roads
limited at controlled junctions.
District Distributor B
Frontage access for residential and commercial
purposes to b limited.
Pedestrian crossing to be located at sites where
safety and function of the
roads is not in any way compromised e.g. bus
stops and traffic light
intersections.
Carriageway to be undivided with at least 4
lanes being provided.
Speed limited to be 60 kmh.
Consideration should be made for bus routes and
separate bus bays to be allocated.
Preferable no parking with clearway if
necessary.
Minimum carriageway width to be 7.4m.
Bicycle lanes to be provided parallel to street
with wider kerbside lanes.
Access points to Primary Distributor B to be
considered in any Local Area
Traffic Management Schemes.
Combined access ways and access through service
roads ROW to be
encouraged. Right turns into District
Distributors B roads limited at controlled junctions.
Local Distributors carry traffic within a cell
and link district distributors at the
boundary to access roads. The route of the local
distributor discourages through
traffic so that the cell formed by the grid of
district only carried traffic belonging to or serving the area.
In these local distributors frontage access to
all lots permitted. For corner lots, access off Secondary Street to be
encouraged. Maximum desirable speed limit between 40-60 kmh. Road closures or
diversions not encouraged. Traffic calming devices seen as a last resort.
Street parking allowed, unless stated. Probable bus routes.
Access Roads only give access to abutting
properties. As the lowest order road, the access streets usually carries no
through traffic. Their design requirements are controlled by the land uses of
the area. With properly designed access streets without through traffic, travel
distances from residences to collector streets are short, traffic speeds are
low, lane capacity and design speed are not controlling design factors, and
minor delays are inconsequential considerations. Drivers and residents expect and accept both brief delays and the
need to decrease speed. It is customary
for the individual to drive carefully to avoid children and pets. Generally it
can be said that in residential areas the amenity, safety and aesthetic aspects
of access road design takes priority over speed of vehicles movement.
Frontage access is permitted for all lots within
the access roads. Ensure roads connected to District Distributors at suitable
locations. Maximum desirable speed limit desirable should be 40 kmh. Street
parking allowed. Road closures if justified. Bus routes not supported.
Undivided carriageway.
The dominance of traffic as a problem on all
street types is the most salient and counterintuitive threat. A distinction
must be made at this point between the priorities and concerns of people when
deciding residential streets. There are a number of needs for a low income Road
Hierarchy and Targets. The community needs to gain maximum value for its
investments in roads. Competing demands for public funds have resulted in
decreasing money being available for road works. This road hierarchy will help
the Government to strategically prioritise new road construction, road
re-instatement and maintenance of the State Roads, which in this instance
include those owned and maintained by its local authority branch. It will also
assist in determining their standards.
Most residents are pedestrians for some of their
journeys. They therefore require the opportunity to use safe, direct, secure
and visually attractive routes to destinations such as local bus stops, shops,
schools, parks and other community facilities, as well as the surrounding
countryside. Over the past decade initiatives have resulted in a significant
growth in pedestrian activity as people walk to work and to schools. This
encouraging increase is due in part to the creation of a Pedestrian Strategy, which
includes an awareness of the benefits of walking and the development of a
citywide network of priority pedestrian routes, which are safe, convenient and
easy to use. The key to accommodating the pedestrian is the creation of a walk
able neighbourhood. This can be achieved through the detailed design of
footpaths and pedestrian areas, which reduce the dominance of the car.
Consideration should also be given to children
play patterns, as it is common for residential roads to be crossed frequently
by children. Carriageways and parking areas may also be used as play areas
within the development.
Pedestrian footpaths should link up with traffic
calming schemes to provide a safer and more pleasant environment. The walking
network should be accessible for disabled people, ensuring greater mobility.
Unnecessary obstructions are controlled and surfaces are well maintained.
Personal security is given a high consideration when routes are designed and
high quality lighting is provided where appropriate. Where the walking network
has to cross roads, crossing facilities are provided appropriate to the
circumstances. Traffic signal controlled crossings are responsive to pedestrian
demand and do not impose excessive wait times. All such crossings are fully
accessible for disabled people. Walking should be regarded as the acceptable
norm for short distance trips. Access for the elderly and people with mobility
problems can be improved by providing dropped kerbs, tactile paving. Over half
of light street residents are troubled about the dangers for their children, if
not on their own street, then traveling in the neighbourhood. These are the
streets used as the short cuts when the heavier streets are congested, they are
the streets through which hot-rodders and motorcyclists can race. It is also
common to find out that there is lack of maintenance, noise, air pollution,
trucks, parking etc.
Cycling is one of the most environmentally
friendly forms of transport, but unfortunately despite the health benefits
cyclists are one of the most vulnerable groups of road user. Children are
particularly at risk when out at plays around the home or when going to and
from school. Their safety is largely dependent on the flow and speed of motor
traffic, which can be regulated through the design process. It is therefore
paramount when designing a residential area that proper provision is made for
cyclists by the creation of safe, direct and secure routes and facilities. It
will be a requirement for all new development to encourage the use of cycling
by the creation of direct, low traffic flow and low traffic speed links to the
cycle network and to local shops, schools and other facilities.
It is estimated that a significant part of the
population does not have access to a private car. It is therefore essential
that a viable network of public transport services is available to these
people. Whilst it is acknowledged that a percentage of residential developments
will not be large enough or of such design that the penetration of buses will be
practical, it is nevertheless essential that good, direct and secure links are
provided to the public transport network for both pedestrians and cyclists.
Whilst the patronage of public transport may appear low compared with other
modes, the partnership between the City and public transport operators has led
to an increase since the partnership began. The development of
"metro" style services along major corridors of movement,
complemented by the Easylink Service, help to provide services in areas of lower
demand.
They also provide more accessible services with
good penetration of residential areas for those people for whom a good local
bus or minibus service is vital to their personal mobility, and should
encourage greater usage. In all new residential developments the potential for
improved public transport accessibility needs to be assessed, whether this is
through direct access or via links to the existing network. Pedestrian and
cycle links to bus stops with improved facilities for waiting passengers in a
safe, secure and well lit manner will be a requirement in new development.
Access for emergency vehicles goes without
saying, but dependent upon the nature and size of the development will depend
on the degree of access required, particularly for fire emergencies, and other
Rescue Service. Access for ambulances is often taken for granted in the road
hierarchy design.
Off-Street Parking, but parking provision should
be framed with good design in mind recognising that car ownership varies with
income, age, and the type of housing and its location. It is however, important
to state at this point, that proper and adequate car parking must be provided
in a safe and secure location, close to the home and in sight of their owners,
but must not dominate the street scene, as can happen with low income
residential area.
The Council will seek to minimise car parking
standards taking into consideration the location and the recommended maximum
car parking provision where good alternative forms of transport are available.
The judicious use of landscaping and screening can play an important role in
reducing the impact of the private car.
In a low income residential area problems are
fairly intractable if people cannot pay for the garbage collection some
residents said they could or would not unless the city were to provide these
streets with more frequent street sweepers and larger trash receptacles. It is
common to find abandoned cars in the streets. Thus there is need to control
parking in the streets and the removal of abandoned cars and planting trees
along roadsides.
Road design principles in the outer
neighborhood. There are also a number of facts that should be considered to
enhance traffic movement in the sited low-income residential area. One should
not just design a road hierarchy without taking due concern of the residents,
that is the layout as opposed to the living style of the locals. Examples of
New Traffic Management Schemes
Home Zones comprise residential streets designed
to give greater priority to people over cars and to encourage greater social
activity on the street. Vehicles should only be able to travel a little faster
than walking pace (less than 10 mph).
This means that the street layouts are
completely redesigned to slow traffic, but also to include, amongst other
things, children play areas, planting trees, cycle parking and seats for
residents to use. Home Zones should therefore make residential areas safer for
pedestrians and cyclists, and improve the quality of the
street environment. Home Zones aim to improve
the local quality of life in residential streets - by making them places
At this point one starts to talk about the site
design and its factors.
There should be a clear street hierarchy for
improved way finding. Smaller streets should have smaller lots. Opaque privacy
fences and sound walls should not separate housing from open space or roadways.
Houses and entries should have a street orientation. Every lot should have a
street tree as specified in the design guidelines.
From an architectural point of design. Housing should have simple roof forms with
roof ridges running parallel with the street. Houses should have street-facing
porches. Corner lot houses should have visual interest on each street frontage
(no blank walls).
The nature of road hierarchy has a lot of
bearing on the movement of traffic. It is also the main cause of congestion.
Although it is very hard to tell about the exact causes of congestion as it
does not follow any pattern. It is a common practice in low-income residential
areas to blame pushcarts as the only reason for creating traffic congestion.
But in reality there are several of reasons behind this problem.
Effective reasons include significant increase in population and
also all types of vehicles. Simultaneous presence of motorized and
non-motorized vehicles on the same street. Both motorized and non-motorized
vehicles occupy the same streets at the same time. Their speed is different and
that is why it creates chaos and congestion on the street. Most of the
pushcarts "pushers," or drivers, do not have any training and they
are not even aware of the traffic rules.
Traffic mismanagement the violation of traffic
rules and regulations. Insufficient number of traffic police and traffic
signals, flaws in traffic markings, violation of traffic rules and regulations
etc can also be cited as some of the main reasons for traffic congestion in
high-density areas. There is a lack of education and consciousness among the
citizenry about the traffic rules. People who come to the city from villages
for employment, pushcarts pulling become the most easily available job for
them.
They do
not need any formal training to start this profession. In most of the cases,
they do not even take a legal license if there are any. Most of the time, the
pedestrians cross the busy streets even if there is no crosswalk.
An example is when people cross busy roads at
peak periods while going or coming from work in Mutare from Paulington
industrial area in Sakubva Suburb in Harare as they cross Mazorodze road to
Mbare. People do not usually use the over bridges or underpasses, which are
constructed in the important and busy intersections of the city as seen from
CBD to Mbare in Harare. The buses do not stop at the bus stops; they stop just
at the intersection points. As a result, the intersections of the busy roads
always remain crowded by the people and different types of vehicles.
Improper Implementation of Traffic Rules. People
usually do not want to follow the traffic rules, as there is no proper
implementation of these rules. Even though traffic police is usually present at
every nodes or intersections along major feeder roads, they do not do their
duties properly. Traffic rules are also very flexible. One can easily avoid the
fine by giving bribe to the police.
Encroachment of roads and sidewalks by street
vendors, hawkers and street front shop owners. Construction materials, garbage
or even temporary houses of homeless people or beggars mostly in new suburbs
also fill up the sidewalks. Very often pedestrians are forced to walk on the
main roads instead of using the sidewalks because of these reasons.
Poor transportation and infrastructure planning.
Traffic Signals
A
traffic signal is used to manage traffic and pedestrians at heavily used,
extremely hazardous, or complex intersection.
Installing a traffic signal is expensive, so
every available factor must be thoroughly analyzed the need for installation
must be appraised, and that need ranked in relation to others. Traffic signals
can serve either a single intersection or can be part of a coordinated traffic
control system designed to provide optimum flow along a route during periods of
varying demand. Since the thrust of neighbourhood plans is to divert more
traffic to the arterial collector system maintenance of optimum flow conditions
on that system since desirable.
The lack of protected left -turn phasing (and
left turn storage lanes) at many intersections along the designated circulation
system is sometimes a cause of through -traffic intrusion into neighbourhoods
where drivers can avoid the difficulty of making a left turn at a busy
intersection. However, providing left turn lanes at most intersections would
reduce arterial capacities.
traffic circles and islands
Traffic circles provide some reduction in speed,
especially close to the intersection, although success is directly related to
the usable approach width, where parking is heavy and provides a physical
barrier that narrows the approach, drivers tend to slow down at the intersection.
Where parking is spaced, artificial narrowing must be used to create a narrow
approach. One problem with traffic circles is that they change the relationship
between vehicles and bicycles, which is especially critical when vehicles are
forced close to curb in order to turn around the circle. Conflicts with
pedestrians also occur especially when there are no protected sidewalks or
pathways for pedestrian use.
Conclusion
The Dutch system contains 3
categories or Tiers of road
Roads with through function for
rapid movement of through traffic. Distributor for the distribution and
collection of traffic between different districts and residential areas. Roads
with an access function providing access to property whilst ensuring the safety
of the street as a meeting place.
The control of road hierarchy have
highlighted that there are certain principles which you will need to consider
when developing a hierarchy, these include:
•ensuring the vehicle/user is using
the most appropriate route
•setting criteria for developing
categories within the hierarchy
•assessing the types of route that
are currently available
•categorising routes in accordance
with their size, surface and location •acknowledging potential conflict between
different types of user
•the importance of signage for
directing users within the hierarchy
There are 3 categories or Tiers of
road, which can be summarised as roads with through function for rapid movement
of through traffic. Distributor for the distribution and collection of traffic
between different districts and residential areas. Roads with an access
function providing access to property whilst ensuring the safety of the street
as a meeting place.
Bibliography
(1) C A O'Flaherty, Traffic planning
and Engineering, Highways, 1986.
(2) Donald Appleyard, Livable
Streets, protected neighborhoods, 1981.
(3) HP White and ML Senior,
Transport Geography, 1991.
(4) Charcles E Pinkus and Disxson,
Solving Local Government Problems,
{Practical Applications of
Operations Research in Cities and Regions}, 1981.
(5) Internet.