Central Business District The CBD or Central Business District is the focal point of a city. It is the commercial, office, retail, and cultural center of the city and usually is the center point for transportation networks. There are no boundaries to the CBD. The CBD is essentially about perception. It is usually the "postcard image" one has of a particular city. There have been various attempts at delineating the boundaries of the CBD but, for the most part, one can visually or instinctively know when the CBD starts and ends as it is the core and contains a plethora of tall buildings, high density, a lack of parking, transportation nodes, a large number of pedestrians on the streets and generally just a lot of activity during the daytime. The "CBD" is the central district of a city, usually typified by a concentration of retail and commercial buildings. City centre differs from downtown in that the latter can be geographically located anywhere in a city, while a city centre is generally located near the geographic heart of the city. Source: http://en.wikipedia.org/wiki/Central_business_district
The shape and type of a CBD or downtown almost always closely reflects the city's history. Cities with maximum building height restrictions often have a separate historic section quite apart from the financial and administrative district. Central business districts usually have very small residential population. Goals and Concepts of a C.B.D. • The ultimate goal to which nearly every major city aspires is to create an environment conducive to a lively atmosphere and satisfying day/night variety of “People Activities”. • The building of a balanced mix of new office, shopping and recreational facilities which must include the extension of facilities to attract people in the after business hours, e.g, theater, sports, music and special events; the diversification of jobs and an increase in the employment opportunities. The provision for multilevel parking for private and public sectors, the preservation and restoration of buildings of historical heritage add a character to the city and creates an interest for the citizens. • The provision for protected pedestrian walkways (whether elevated, at ground level, or underground) linking the major shopping, office and the municipal buildings. Source: Redstone, Louis G., The New Downtowns (Rebuilding Business Districts), 1976, Pg: 19
Historical Background The CBD developed as the market square in ancient cities. On market days, farmers, merchants and consumers would gather in the center of the city to exchange, buy, and sell goods. This ancient market is the forerunner to the CBD. As cities grew and developed, CBDs became fixed location where retail and commerce took place. The CBD is typically at or near the oldest part of the city and is often near a major transportation route that provided the site for the city's location, such as a river, railroad, or highway. Over time, the CBD developed into a center of finance and control or government as well as office space. In the early 1900s, European and American cities had CBDs that featured primarily retail and commercial cores. In the mid-20th century, the CBD expanded to include office space and commercial businesses while retail took a back seat. The growth of the skyscraper occurred in CBDs, making them more and more dense. Source: http://en.wikipedia.org/wiki/Central_business_district
Agora The Roman Agora served as a marketplace where merchants kept stalls or shops to sell their goods amid colonnades. Actually Agora served as a twin function of being a centre for political and commercial space activity. Forum A forum was the public space in the middle of a Roman city.In addition to its standard function as a marketplace, Forum was a gathering place of great social significance, and often the scene of diverse activities, including political discussions and debates, meetings, et cetera. Bazaar A bazaar was a permanent merchandising area, marketplace, or street of shops where goods and services are exchanged or sold. The word derives from the Persian word bāzār, meaning "the place of prices". Although the current meaning of the word is believed to have originated in Persia, its use has spread and now has been accepted into the vernacular in countries around the world. Source: http://en.wikipedia.org/wiki/agora http://en.wikipedia.org/wiki/forum http://en.wikipedia.org/wiki/bazaar
Souq A souq is a commercial quarter in an Arab or Berber city. The term is often used to designate the market in any Arabized or Muslim city. In Modern Standard Arabic the term refers to markets in both the physical sense and the abstract economic sense. Mercado Mercado in Mexico and throughout Latin America combines the elements of open-air street markets, and the more formal structures that house the bigger vendors in the major cities. Many of the Mercado have the qualities of the Mexico city’s tiangus, street markets selling a variety of goods from produce to small appliances, clothing and handicrafts that setup in different neighbourhoods each day of the week, providing variety and stability at the same time. Source: http://en.wikipedia.org/wiki/souq http://en.wikipedia.org/wiki/mercado
CBD Factory zone Zone of transition Working class zone Residential zone Commuter zone Urban Structure Urban structure is the arrangement of land use in urban areas. Sociologists, economists, and geographers have developed several models, explaining where different types of people and businesses tend to exist within the urban setting. Urban structure can also refer to the urban spatial structure, which concerns the arrangement of public and private space in cities and the degree of connectivity and accessibility. Concentric Ring Model The Concentric ring model also known as the Burgess model is one of the earliest theoretical models to explain urban social structures. It was created by sociologist Ernest Burgess in 1925. • The zones identified are: • The center was the CBD • The transition zone of mixed residential and commercial uses • Low-class residential homes (inner suburbs), in later decades called inner city • Better quality middle-class homes (Outer Suburbs) • Commuters zone Source: http://en.wikipedia.org/wiki/urban_structure http://en.wikipedia.org/wiki/concentric_ring_model
Sector Model The sector model, also known as the Hoyt model, is a model of urban land use proposed in 1939 by economist Homer Hoyt. It is a modification of the concentric zone model of city development. The benefits of the application of this model include the fact it allows for an outward progression of growth. As with all simple models of complex phenomena its validity is limited. Source: http://en.wikipedia.org/wiki/sector_model
Multiple Nuclei Model The multiple nuclei model is an ecological model put forth by Chauncy Harris and Edward Ullman in the 1945 article "The Nature of Cities." The model describes the layout of a city. It notes that while a city may have started with a central business district, similar industries with common land-use and financial requirements are established near each other. These groupings influence their immediate neighborhood. Hotels and restaurants spring up around airports, for example. The number and kinds of nuclei mark a city's growth. The theory was formed based on the idea that people have greater movement due to increased car ownership. This increase of movement allows for the specialization of regional centers (eg. heavy industry, business park). There is no clear CBD (Central Business District) in this type of model. Source: http://en.wikipedia.org/wiki/multiple_nuclei_model
The Core - Frame Model of a C.B.D. The Core frame model is a model showing the urban structure of the Central Business District of a town or city. The model includes an inner core where land is expensive and used intensively, resulting in vertical development. This area is the focus of the transport system and has a concentrated daytime population. The outer core and frame have lower land values and are less intensively developed. The various land uses are linked to the bid rent theory. The zone of assimilation and zone of discard are together called the zone of transition. Source: http://en.wikipedia.org/wiki/zone_of_transition
Basic Layouts of the CBD Layout I • It introduces separate area for pedestrians in the form of a pedestrian mall. • Service traffic is not separate from customer traffic. • Long walk from parking to access. Layout II • It shows a similar layout but end placed structures are activity notes like a museum or library. • Access to parking is provided by a circulatory road within the site itself. • Introduction of basement delivery road. Layout III • It shows an arrangement with three different blocks enclosing a common space. • Pedestrian flow would tend to flow from one of the main magnet to another. • Produces a variety of spaces.
Layout IV • In this layout a centralized parking is provided with a peripheral service road, which leads to segregation of customer and service traffic. • Store fronts and signs can be viewed both from public road and parking lot. • One major disadvantage of this layout is that it faces rush and traffic jams during peak hours when offices open and close for work. Layout V • It represents an approach with one court & two magnets placed in diagonal manner. • Complex is widened by court. This court can be used for public events, kiosks etc. • Provides equal opportunities to the stores. • Even distribution of pedestrian flow. Layout IV • This shows approach to the centre with two magnets. • This is simplest and most often used solution.
Essential Features of a Central Business District: • If an area meets many or all of the following criteria, it would probably be considered a CBD: • Houses large public buildings such as libraries, churches, stations and town halls. • Contains specialist shops and branches of major department stores. • Contains social amenities such as cinema halls, clubs and theatres. • Contains little housing, but often hotels. • Contains little or no industry. • Contains offices and other professional buildings. • Contains buildings that tend to be taller than other buildings in the city (because land prices tend to be at a premium, making high-rise buildings economically favorable) • Has high pedestrian levels and the greatest parking restrictions. • Often is the geographical centre of the settlement. • Often is the area with the highest land value. • Is well connected by public transport, with large numbers of passengers. • Has a high traffic level. Source: http://en.wikipedia.org/wiki/Central_business_district
The Modern CBD By the beginning of the 21st century, the CBD had become a diverse region of the metropolitan area and included residential, retail, commercial, universities, entertainment, government, financial institutions, medical centers, and culture. The experts of the city are often located at workplaces or institutions in the CBD – lawyers, doctors, academics, government officials and bureaucrats, entertainers, directors and financiers. In recent decades, the combination of residential expansion and development of shopping malls as entertainment centers have given the CBD new life. One can now find, in addition to housing, mega-malls, theaters, museums, and stadiums. Pedestrian Malls Pedestrian malls are also common today in CBDs in an effort to make the CBD a 24 hour a day destination for not only those who work in the CBD but also to bring in people to live and to play in the CBD, keeping the vehicular movement restricted to the outskirts and to a minimum. Without entertainment and cultural opportunities, the CBD is often far more populated during the day than at night as relatively few workers live in the CBD and most do commute to their jobs in the CBD. Source: http://en.wikipedia.org/wiki/Central_business_district
Land Value and the Bid Rent Theory Land users, whether they be retail; office; or residential, all compete for the most accessible land within the CBD. The amount they are willing to pay is called bid rent. This can generally be shown in a ‘bid rent curve’. Based upon the reasoning that the more accessible the land, generally in the centre, is the more expensive land. • Commerce (in particular large department stores/chain stores) is willing to pay the greatest rent to be located in the inner core. The inner core is very valuable for them because it is traditionally the most accessible location for a large population. As a result, they are willing and able to pay a very high land rent value. • As you move from the inner core, the amount commerce is willing to pay declines rapidly. Industry, however, is willing to pay to be in the outer core. • As you move further out, so the land is less attractive to industry due to the reducing communication links and a decreasing market place. Because the householder does not rely heavily on these and can now afford the reduced costs (when compared with the inner and outer core) is able to purchase land. • The further you go from the inner core and outer core, the cheaper the land. This is why inner city areas are very densely populated (terraces, flats and high rises), whilst the suburbs and rural areas are sparsely populated (semi and detached houses with gardens). Source: http://en.wikipedia.org/wiki/Central_business_district
Central Business District- Components GENERAL APPEARANCE • The study of various aspects like urban and open spaces , enclosure and relation of buildings is important at planning stage. Design harmony among buildings is attained by describing a predominant character to urban spaces. • An interesting skyline is maintained along with landscaped green open spaces and plantings to create a unifying design concept among the buildings. • Variety of vistas, visual focal points and views are created along with interesting architectural details. • Unnecessary signs, poles and wires add visual chaos to the surroundings so they need to be avoided and vacancies are to created that allow space for expansion. • A urban space must be distinguished by a predominant character: • Quality of enclosure • Quality of its detailed treatment • Activity that takes place in it • The scale of open spaces is determined by trees, rocks, shrubs and group surface rather than their gross width and length. • Assuming that the CBD will be served by accessible transport, we need to introduce the universal design elements in the physical design of CBD. The proposed design for the CDB has been modified for the following components. Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-6.6-9,10
THE GRAND PUBLIC SPACE A public space is a social space such as a town square that is open and accessible to all, regardless of gender, race, ethnicity, age or socio-economic level. Located near a diversity of land uses( office, retail, warehouses) it tends to attract the users from a greater distances and in a great variety. Such a plaza is often big and and flexible enough to host the brown-bag lunch crowds, outdoor cafes; passers through; and the occasional concerts, art shows, exhibits, and rallies. • The street plaza: an area predominately hard surfaced, centrally located, and highly visible. It is often the setting for programmed events such as concerts, performances etc. • The city square: a centrally located, often historic place where major thorough fares intersect. It is usually bounded by streets. Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-6.-1
WALKWAY SYSTEMS AND SKYWAY BRIDGES • Elevated walkway systems are a comparatively recent development in the provision of a pedestrian linkage to the major buildings in the most effective area of the central business district. • These second level passages not only offers protection from bad weather but also afford the pedestrians a safe and pleasant means of circulation within the CBD, completely separated from the motor vehicles and their pollutants. • The space in the buildings connected by skyways is often devoted to retail business, so areas around the skyway may operate as a shopping mall. • Primarily, the skyway plan consists of - • Mid-block crossings which connect the interior arcades through the buildings to form one continuous system. • . • They also connect with a series of strategically located enclosed courts which provide comfort and beauty and provide for year-round activities. Source: Redstone, Louis G., The New Downtowns (Rebuilding Business Districts), 1976, Pg: 29
INFORMATIONS AND SIGNS • Signage serves two functions— • Provide direction of flow to occasional visitors and new employees in cbd • to convey information and to attract attention. The overall facade composition, including ornamental details, color and materials, should be considered when determining the location, size and character of signage. • Points of consideration: • SIGN DESIGN. • Consider both pedestrian and vehicular traffic in • selecting and designing signage. • 2.SIGNAGE AND THE BUILDING Signage should be low-key in order to avoid competition with the architecture of the structure. Materials and design should be compatible with the building’s materials and style. Locate signs so that they emphasize design elements of the facade, but do not obscure architectural details, windows or other significant features. Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-6.8-11
Signs can also reinforce the horizontal lines of moldings and transoms, and accent architectural details when placed appropriately. • The design and style of both the lettering and sign should complement the style of the building. • Signs for multiple businesses in a single building should be designed with similar materials, backs and lettering styles. 3.MATERIALS Glass, painted wood, painted metal or architectural decorative metals such as copper, bronze, brass, aluminum or stainless steel are appropriate sign materials. Unfinished, non-decorative materials, including unpainted wood and highly reflective materials are discouraged. Plastic is only allowed as individual three dimensional letters applied to a sign or building, or where the face of an existing sign is to be replaced with like materials. 4.SIGN LIGHTING. Sign lighting should be indirect, not bright and glaring. Internal illumination of signs is prohibited. Neon lighting should be used only in small amounts and where appropriate to the building design. 5.The signs should be such that they direct the visitors to the elevators, restrooms, telephones and cafeterias or coffee shops.
6.On leaving the building, clear signs indicating the way to the transit stop, taxi stands, and the nearby streets. 7.For larger developments and parking lots, directional signs can be incorporated that are designed to be an attractive addition to the streetscape. Public Seating Points of consideration: • 1.The design must recognize that the seating is the most important element in encouraging the plaza use. • 2.The seating meets the needs of the various types of sitters commonly found in most of the plazas. • 3.These seating must be placed in those locations that are not sunny during the lunch hours; in the shade. • 4.Secondary seating (mounts of grass, steps with a view, seating walls, retaining walls that allow sitting) must be incorporated in the plaza design, to increase the overall seating capacity without creating a “sea of benches” . • 5.A sense of privacy must be created for some of the seating, through the placement of the planters and the other design elements. Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-6.8-7
VENDORS In addition to traditional brick-and-mortar businesses, street vendors also contribute to the urban landscape and can be found throughout downtown’s Central Business District (CBD). • Vending is restricted to specific locations, but in general, vending is allowed on public streets and sidewalks within the CBD and within 300 feet of the CBD. Types of merchandise that can be sold by a street vendor include food, beverages, flowers, cards, pens and regional souvenirs. The sale of clothing items other than T-shirts or caps is not permitted. Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-6.8-10
Street vendors and informal trade, provides employment and incomes to a significant percentage of people, in particular within the urban areas. • The trade takes place at strategic points with heavy human traffic - along main roads, streets, parks, pavements, within shopping centers, and at prominent corners of streets and roads where traders are visible to pedestrians and motorists. • Vending certain types of goods in particular locations increases the popularity of retail areas, enliven the environment of a plaza or a sidewalk, and provides security. • Points of consideration: • The plaza should be designed to accommodate the vendors, whose presence will add to the vitality of that place, provides a measure of security, and often increases the popularity of the surrounding retail outlets. • Providing vendors should be colorful, fabric ”roof” be provided for that area, to draw the attention to the facility, provide the shelter and shade, the contrast with the scale of the CBD buildings. • The area for the vendors or market should be situated so as to be easily accessible and highly visible.
ART IN THE CBD environment In planning the central business district environment, art, in its various forms must become an element that will bring spiritual and aesthetic satisfaction-as important as the part of man’s existence as the satisfaction of purely material needs. Art to be used in the public places such as plazas, playgrounds, lobbies of the government buildings and parks- wherever people congregate . Art in all forms like- sculpture, fountains, special landscaping, well designed lighting, good graphics, outdoor furniture, and interesting sidewalk patterns-can create an exciting atmosphere. Source: Redstone, Louis G., The New Downtowns (Rebuilding Business Districts), 1976, Pg: 55
LANDSCAPING Landscaping helps to soften the harshness of development, and creates attractive areas to view, visit and use.Trees and shrubs help to reduce the amount of wind and dust in an area. Landscaping is especially important for patios,sidewalks and parking areas. • Trees shall be provided along major pedestrian corridors. • Full growth size of tree shall be considered when planting, so there is space between the tree canopy, the building façade, and other architectural elements. • •Trees shall not be placed closer than 30 feet from intersections. They shall remain out of the clear vision triangle. • •Branch height of mature trees on traffic side shall be no less than 13’-6” above the street. • Branch height on pedestrian side shall be no less than 8’above the sidewalk. • •Proper irrigation systems shall be installed to establish and maintain healthy • growth. • •Tree species shall be selected that can withstand the harsh conditions of the urban environment. When an area is to be unified, plant only one species. • •Mature tree height and canopy fullness shall not obscure important building features or business identification. Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-6.8-8
Major Functions of Plant Materials • Aesthetics • Environmental Modification • Screening • Circulation Control • Plants can act as barriers or screens, providing privacy and eliminating trash areas. • To provide visual control planting should be at least 6 feet high. • Depending upon the thickness of the foliage, the size of the branches and the loudness of the sound, noise and sound can be controlled by plants. Mature street trees shall be maintained for clear head clearance.
Plant materials are grouped into general categories relative to their size and habitat .These categories include: • Overstory -- tall plants (typically trees) that form overhead canopies • Understory -- shorter plants (shrubs and small trees) • Ground cover -- plants that grow close to the ground (typically less than 12" tall). May be used to stabilize soil or slopes. • Vines -- plants that attach themselves to other objects for support. • On the basis of texture: fine , medium and coarse
LANDSCAPED TREE NAMES TYPE SIZE AREA Street Trees Thornless Honey Locust 3” caliper Callery Pear Red Oak Littleleaf Linden . Trees for internal White Fir 5 foot for evergreens and screening areas Norway Maple with a 30” spread and Tulip Tree 3” caliper for deciduous Austrian and Red Pine Shrubs for No less than 30” in internal and screening Deciduous and height and 2’ spread areas Evergreen trees Lilac Dogwood Juniper Winterberry Bearberry •
STREETS • A street is a paved public thoroughfare in a built environment. It is a public parcel of land adjoining buildings in an urban context, on which people may freely assemble, interact, and move about. A street can be as simple as a level patch of dirt , but is more often paved with a hard, durable surface such as concrete, cobblestone or brick . • Originally the word "street" simply meant a paved road .The word "street" is still sometimes used colloquially as a synonym for "road", but a crucial modern distinction is that: a road's main function is transportation, while streets facilitate public interaction. • Examples of streets include pedestrian streets, and city-centre streets too crowded for road vehicles to pass. Source: http://en.wikipedia.org/wiki/Streets
ALLEYS An alley or alleyway is a narrow, pedestrian lane found in urban areas which usually runs between or behind buildings. In older cities and towns in Europe, alleys are often what is left of a medieval street network, or a right of way or ancient footpath in an urban setting. In older urban development, alleys were built to allow for deliveries such as coal to the rear of houses. "Alley" is of French origin, meaning "a way to go", and has been adapted in English as a name for avenue or a parkway i.e. any type of road lined with trees. Source: http://en.wikipedia.org/wiki/Alleys
PEDESTRIANS WALKING DISTANCES Walking distances, are important because they are a factor in plan configuration, and a measure of design serviceability. The practical limit of human walking distances appears to be related more to the context and the situation than the human energy. For most persons the maximum tolerable distance is in the range of a normal 5-10 minute walk. • WALKING SPEEDS • The pedestrians vary their walking speeds over a wide range. The average free flow walking speed of the non baggage carrying pedestrians in the surveys, for • all males: 270ft(88m) /min • females: 254ft(77m) /min • and the combination of all the pedestrians: 265ft(80m) /min PEDESTRIAN VOLUME The equation for pedestrians flow volume,(P), in pedestrians per foot width of the pedway section, per minute,(PFM)is expressed as follows: Ped volume= Average Ped Speed,feet/min Average Ped Area, sq.ft/ped Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-6.5-5
HUMAN BODY DIMENSIONS: the body ellipse Body depth and the shoulder breadth are the primary human measurements used by designers of pedestrian spaces and facilities. Shoulder breadth is a factor affecting the practical capacity of the doorways ,passageways, stairways and mechanical devices such as escalators and the moving walks. In a plan view, the average adult human body occupies an area of about 1-1.5 sq.ft(1.4 sqmts). Body depth 18” 24” Shoulder breadth A large ellipse of 18inch by 24inch, equivalent to an area of 2.3 sqft(2 sq.mts), allow for the fact that many pedestrians are carrying personal articles, natural psychological preferences to avoid bodily contact with the others. This determines the practical standard for pedestrian design as an ellipse of 24inch by 18inch.
In this formulation, the designer has a clearer concept of relative design quality, since the units are easier to understand and manipulate. For e.g. a normal average walking speed of 250sq.ft per minute is attained with an approximate average pedestrian area of 25sq.ft.person. the simple division of area occupancy into average speed gives an equivalent design volume of 10 pedestrians per foot(density) width of walkway per minute. • PRINCIPLES OF SAFETY AND SECURITY IN PUBLIC PLACES • Design for the pedestrians to move about in the well-lit, wide circulation routes that reflect the existing patterns of movement • the principle asserts the well-used and the vibrant streets are essential for the safety. Measures that detract from the street life nay increase the risks, such as overhead walkways and underground malls. • Consider safety of people and property together rather than separately • In the traditional Neighbourhood Watch approaches and the Business Watch approaches, it is sometimes assumed that the concern is about robbery rather than the personal safety. Street crime, assault and harassment-less visible than the broken windows and stolen property-have higher economic and social costs. • Use opportunities for enhancing natural surveillance. • Responsible business owners, neighbours and strangers are the best defenses against crime. Urban plazas, parks, pathways and parking lots should be
designed not only to allow people to see and be see and be seen but also be provided with call boxes and graphics clearly indicating ways of helping yourself or getting help. • Provide good maintenance • Good maintenance is crucial for lasting design improvements. Adding lighting does no good if not frequently cleaned or if burned out bulbs are not immediately replaced. A broken fence no longer fulfills its function. Critical maintenance items should be designed for easy access for easy access for cleaning, replacements and repair. • Make sure solutions to one problem don’t cause another • Safety is part of the integrated design objectives to improve urban quality and public amenity. • Active, carefully designed, well lit and well maintained urban places help address all such concerns. • Involve neighborhoods in public safety planning • Local business owners, residents, and community leaders will know local and nuisance patterns that pose safety risks and should be invited to serve a significant role in creating a comprehensive urban design plan for safety and security.
TRAFFIC CALMING • Traffic calming is becoming an increasingly important part of the effort for cities, towns, and villages to become safer and increasingly livable, economically successful and sustainable. • Traffic calming involves physical measures that: • Reduce the negative effects of motor vehicle use, • Alter driver behavior, • Improve the condition for non motorized street users. • Traffic calming slows motorized to a “desired speed” (i-e, the speeds that the community wants);typically 20mhp(32kph) or less for residential streets, and 25-30mhp (40 to 48 kph) on commercial streets, collector streets, and the arterial streets. Traffic calming can be accomplished by: • Retrofitting the existing streets with regularly spaced measures, and/or, • Rebuilding the streets to include the new cross-sections. Source: Watson Donald, Plattus Alan and Shibley Robbert, Time savers standards for urban design, Pg-7.2-1
ROUNDABOUTS • Roundabouts are both traffic calming measure and a highly efficient intersection design. They calm the traffic by introducing the three successive reverse curves of short radius; to the right to enter the circle, and to the right to exit the circle. • Many roundabouts further calm the traffic by reducing the sight distance for oncoming the motorists, with the trees or man-made features in the centre of the roundabout. The size of the central island largely determines the operating speed of the vehicles. Small islands cause little deflection, and therefore provide little speed reduction
Splitter islands are typically used at roundabouts that would otherwise be signalized intersections, because: • They reduce the disparity in speed between circulating and incoming vehicles. • They eliminate the possibility of right-angles collisions.
ROAD INTERSECTIONS It reduce the severity of potential conflicts between motor vehicles, buses, trucks, bicycles, pedestrians, and facilities, while facilitating the convenience, ease, and comfort of people traversing the intersections. • As is the case with other aspects of the highway design process, designers can use a wide range of intersection design elements in combination to provide both operational quality and safety. These include: • Traffic islands to separate conflicting • vehicle movements • Street closures or realignments to simplify • the number and orientation of traffic • movements through an intersection • Separate left and right turn lanes to remove • slow moving or stopped vehicles from • through traffic lanes • Medians and channelized islands to • provide refuge for pedestrians and • bicyclists out of the vehicular traveled way.
Carriage-way Textured pavement raised 3”-5” Zebra crossing Lane Sidewalk corridor/ pedestrian path
DESIGN FEATURES FOR UNIVERSAL DESIGN FROM A MANUAL FOR A BARRIER FREE ENVIRONMENT. Height and design of sill and hanging hoarding for unobstructed shopping arcade. Tactile warning markingon the ground around the obstruction Street furniture at a uniform interval of 100-200m Extra 1.2m to accommodate wheel chair.
Provision of kerbstone along both sides to resist a slippage Seperate 1.5m side walkway for combined walkway traffic of wheelchair and the sightless person. Location of ramps: at parking lots Parking width of 3.6m instead of normal 2.5m width requirement
Parking width of 2.5m with a common aisle of 1.2m Provision of wheel stop to allow free passage of wheelchair • For free movement of wheelchair, the minimum width of walkway should • be 1.5m. • The minimum unobstructed width of walkway should be 0.9m. • The shopping arcade has 6m wide walkway. • The walkways along the open space and along the service road have • minimum width and that is 3m. Thus, the walkway widths conform to • universal design guidelines. • Ramps are introduced at the pedestrian crossing points to let the • wheelchair access the walkway from road. WALKWAY
The transition between walkway and the green landscaped area should be marked with edge stone, which would protrude from the floor of the walkway to alert the sightless persons and also to guide the movement of wheelchair. • None of these elements generate extra cost for implementation but • demands an eye for detail. • All pedestrian crossings will be provided with ramps. This element also does not generate any additional cost but demands designer's attention to detailing. • Proper signaling system should also be installed to allow wheel chair users and other mobility impaired individuals to cross safely. Moreover, the non-users of the facility should be considerate in this matter. CROSSINGS PARKING • A certain percentage of the parking will be transformed into parking for disabled people. Thus, the width of parking will be transformed into 3.6 m instead of 2.5m. Hence, the number of a part of the parking will be reduced to 0.70 (2.5/3.6) times. • The design elements are Kerb stone, Ramps, Tactile materials to be used for surface of walkway, Signaling, Fewer Parking Spaces.
Shops • In order to design satisfactory shops, the first requirement is an understanding of those portions of current merchandising theories which affect the design problem . Briefly, ''merchandising psychology" consists of, first, arousing interest ; second, satisfying it . • Large shop heights vary from 3.9m – 4.57m • Small shop has an optimum height of 3.04m • Basements 3m high permit economical stock storage • Ground floors are usually 4.2m high if no mezzanine is included. • Mezzanines should be at least 2.5m above the floor level. • Grids: • Large units between 7.3m x 10.9 on frontage and 9.14m on depth. • Small units between 5.18m x 5.8m on frontage Offices Shop Layouts
Vertical Circulation 1. Staircase : • Interior stairs shall be constructed of non-combustible material throughout. • Stairs shall be constructed as a self-contained unit with at least one side adjacent to an external wall and shall be completely enclosed. • A staircase shall not be arranged round a lift shaft for building 15.0 mt. and above height. • The stair-case & lifts shall be so located that it shall be within accessible distance of not more than 25 Mts. from any entrance of tenement or an office provided on each floor. • The minimum width of treads without nosing shall be 30 cm. for a commercial high-rise buildings. The treads shall be constructed and maintained in a manner to prevent slipping. No winders shall be allowed. • The maximum height of riser shall be 15 cm. in the case of office buildings and there shall not be more than 12 risers per flight. • Handrails shall be provided with a minimum height of 100 cm. from the center of the tread. • Minimum headroom shall be of 2.1m. 2. Ramp : • Inclined plane or surface connecting different levels; a stair without a risers, to enable a person to climb without interruption and to permit the use of wheeled carts, chair or vehicles. • A ramp when provided shall not have a slope greater than 1 : 12. Larger slopes shall be provided for special uses but in no case greater than 1 : 8. • Minimum clear width shall be 36” (3 feet).The minimum width of the ramps in the basement using car parking shall be 6.0 mt. • Handrails shall be provided on both sides of the ramp. • Ramps shall have level landings at bottom and top of each ramp and each ramp run. • If ramps change direction at landings, the minimum landing size shall be 60” x 60”. • Each ramp shall have at least 180 cm of straight clearance at the bottom. Source: Neufert, Ernst and Peter, Architects’ Data, Third Edition, Pg -444 National Building Code of India 2005, Pg – 113
3. Lifts or Elevators : • The upward and downward moment of people in newly erected multi-storey buildings is achieved by lifts. • In large multistory building it is usual to look at the lifts at a central pedestrian circulation point. • Lift position should be such that it does not obstruct the main entrance to the building and adjacent to the principle staircase. • Area allowed varies from 0.14- 0.28 sq m per person. • For a block of offices of not more than five stories the speed may be from 37 to 60 m per min. • For a multistory departmental store with a restaurant on the top floor, speed of 90 to 120 m per min. • A lift shall be provided in buildings as prescribed hereunder: • (i) In case of Building having height more than 13.0 Mts. lift shall be provided. • (ii) Lift shall be provided of one lift per 1000.00 sq.mts. or part thereof of built-up area for commercial buildings. Passenger Lift Source: National Building Code of India 2005, Pg – 971
Elevators for Disabled • In multi-storey building elevators are principal means of vertical circulation for those confined to wheelchairs and for others with difficulty in walking. • Minimum dims of elevator car to accommodate standard wheelchair:1100 internal depth, 900width , 700 clear door opening. • In public building there should be sufficient space for another person to accompany chair-bond:1400 min. width, 1100 width. • In special residential homes large wheelchairs are to be accommodated; dimensions:1800 depth ,1000width, 800 door opening. • Elevator cars must be accurate in leveling and at landings. • Photoelectric devices in doors to prevent premature closing desirable . • Control buttons should light to operate . • Mean height should be 1400, max 1600 • To position wheel chairs there should be clear space at least 1500 x 1500 before each lift door.
4. Escalators : • An escalator is a moving staircase conveyor transport device for carrying people between floors of a building. It consists of a motor-driven chain of individual, linked steps that move up or down on tracks, allowing the step treads to remain horizontal. • It continuously receives and discharges its live load at a constant speed with practically no waiting periods at any loading. Characteristics • Criss-Cross Escalators • Parallel Escalators • These are Installed at an angle of 300 but within 350 . • Installations are generally 2 speed-with the higher speed (120 fpm) utilized during rush hours and the lower (90 fpm) at off hours. • Moving stairways are generally available in widths of 32” and 48”, measured at hip level between the balustrades; 40” can carry 2 persons/tread. • 32” has a tread width of 24” and 48” width has 40” tread. • All treads have a rise of 8” and 16” depth. • 32” wide step-5, 000 passengers/hour, with a speed of 90 fpm, and 6,666 passengers/hour with a speed of 120 fpm. • 48” wide step-8, 000 passengers/hr with 90 fpm speed and 10,665 passengers/hr at a speed of 120 fpm. Source: National Building Code of India 2005, Pg – 996, 997
Specifications Source: KONE standards