Street elements

Street design elements are the various components of a street that accommodate or serve specific functions for various users, including pedestrians, cyclists, public transport riders, and car users. These elements require detailed planning and customisation to fit the local context. Achieving the right balance and placement of these elements can be challenging, as they all interact with one another.

Street elements play a crucial role in ensuring that all users can safely and efficiently travel through the street network. Therefore, it is essential to consider the interaction between all the street design elements to ensure that they work together seamlessly. The figure to the right shows the main street elements.

Footpaths

Good footpaths promote safe and comfortable pedestrian mobility. Comfort, continuity, and safety are the governing criteria for the design and construction of pedestrian facilities. For this reason, the footpaths are divided into three main zones:

  • Pedestrian zone: This zone provides continuous space for walking and should be clear of any obstructions. It should be at least 2 m wide.
  • Frontage zone: Provides a buffer between street-side activities and the pedestrian zone. Next to a compound wall, the frontage zone can become a plantation strip.
  • Furniture zone: This is a space for landscaping, furniture, lights, bus stops, signs, and private property access ramps. 

Crossings

Good crossings allow pedestrians and cyclists to cross busy streets safely and conveniently. A formal pedestrian crossing should be located wherever there is a concentrated need for people to cross the street (e.g., at a bus stop, at an entrance to a shopping mall, or where a path intersects the street). In busy commercial areas, crossings should be spaced at more frequent intervals.

At-grade crossings are superior to pedestrian footbridges or tunnels. Pedestrians dislike having to climb a stairway in order to cross the street, so they are likely to avoid it and cross at-grade as they please. This preference makes costly footbridges and tunnels an unwise use of limited resources.

Design standards

  • Located at pedestrian desire lines.
  • Signalised or raised to the level of the footpath to calm traffic. Footbridges and subways are to be avoided.
  • For tabletop crossings, a height of +150 mm above the carriageway and ramps for vehicles with a slope of 1:8 to reduce vehicle speeds to 15 km/h.
  • If a speed hump is used, the hump should be placed 5 m before the crossing.
  • Drainage inlets should be provided upstream of the tabletop crossing to prevent water logging.
  • Width of 5 m or equivalent to the adjacent footpath, whichever is larger. f Bulb-outs in parking lanes to reduce the crossing distance.
  • Where median fences are installed to prevent crossing, informal crossings in the form of breaks in the fencing should be provided wherever there is demand.
  • Refuge islands to provide spaces for pedestrians to wait before crossing the next stream of traffic.

Cycle tracks

On streets with faster speeds, cycle tracks can reduce conflicts between cycles and motor vehicles. Cycle tracks make it possible for even novice users to opt for cycling. Efficient cycle tracks are safe, convenient, continuous, and direct.

Design standards

  • Physically separated from the carriageway as distinguished from painted cycle lanes, which offer little protection to cyclists.
  • A minimum clear width of 2 m for one-way movement, and 3.0 m for two-way movement.
  • Elevated +150 mm above the carriageway.
  • Positioned between the footpath and carriageway. Provide a buffer of at least 0.5 m between the cycle track and carriageway. The buffer should be paved if it is adjacent to a parking lane. Increase the buffer to 0.75 m next to buildings, walls, etc.
  • The buffer should be at least 0.5 m wide and should be paved if it is adjacent to a parking lane.
  • Bollards to prevent encroachments by cars. One bollard placed in the middle of the cycle track, to allow for cyclists to pass on either side. Bollard spacing of 1.2 m.
  • A smooth surface material—asphalt or concrete. Paver blocks are to be avoided.

 

Bus rapid transit

As cities and urban centres grow, exclusive corridors for public transport can help increase the passenger carrying capacity of urban streets. Public transport lanes carry a large number of people with lower cost and time as compared to mixed traffic lanes. They also reduce expenditure on fuel, air pollution, and traffic congestion and are therefore more sustainable than wide roads devoted to personal motor vehicles. Bus rapid transit (BRT) can offer high-capacity and high-quality public transport service at a fraction of the cost of rail systems. BRT can anchor transit-oriented development, facilitating compact, inclusive urban growth.

Design standards

  • Exclusive BRT lanes with a width of 3.5 m must be provided in the centre of the street. The lanes should be separated from mixed traffic through a physical barrier
  • Centrally located BRT stations require a width of 4 m. Larger widths may be required if demand is high.
  • Having the bus-station platform level with the bus floor is one of the most important ways of reducing boarding and alighting times per passenger. Passengers climbing even relatively minor steps can mean significant delay and an increase in safety hazards, particularly for the elderly, disabled, or people with suitcases or strollers.
  • Safe pedestrian access should be provided via crosswalks elevated to the level of the footpath (e.g., +150 mm). At crossings, a 1 m pedestrian refuge between mixed traffic and a BRT lane is needed. At stations, the BRT lanes should be raised to +150 mm for the length of the station, with a ramp slope of 1:100 for buses, to match the level of the elevated crosswalks.
  • To achieve capacities as high as those of metro systems, passing lanes, multiple sub- stops, and express services are required at BRT stations.
  • Stations should be placed at least 40 m from intersection stop lines to allow sufficient space for bus and mixed traffic queues.
  • Two-phase intersections to minimise delays for buses.
  • Maximum grade of 5% for BRT lanes and 2% at stations.
  • Cycle parking is needed at stations.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Carriageway

Street space should be allocated to the carriageway after adequate usable space has been reserved for walking, cycling, trees, public transport (including BRT if the street falls on the city’s rapid transit network), and street vending. Otherwise, such activities will spill over onto the carriageway. Carriageway width is not determined by available ROW.

The carriageway should be designed for appropriate speeds suited to the street’s role in the network. When carriageways become congested, they can no longer fulfil their role of providing for vehicle mobility. This can be addressed through parking pricing and other travel demand management measures to reduce the number of vehicles on the street. These measures reduce congestion, thereby improving conditions for the remaining users.

Design standards

  • Width defined by the function of the street rather than the available right-of-way.
  • On major streets, a width of 6.0-6.5 m for two lanes can accommodate large vehicles such as trucks and buses. Carriageways on urban streets should not be wider than three lanes or 9.0-9.75 m per direction. In industrial zones, a 3.5 m lane width is acceptable.
  • Constant width, thereby ensuring the smooth flow of vehicles. The width should not increase on stretches where a wider right-of-way is temporarily available. Wider carriageway segments cause traffic jams where the width narrows again.
  • Design speeds related to the street’s function. Speeds can range from 10-30 km/h on local streets to 30-40 km/h on collector streets and 50 km/h on arterial streets.
  • In the case of narrow, traffic-calmed streets, carriageways are replaced by shared space where motor vehicles, pedestrians, and cyclists coexist, with speeds no higher than 10- 15 km/h.
  • Superelevation is generally not used on low-speed (70 km/h or less) streets in unban areas. It negatively impacts drainage, footpaths, adjacent properties, intersections, and vehicle speed. Instead, streets are to be crowned with maximum 2.0% cross-slope (2.5% where there is heavy rain).
  • Horizontal curves are designed to manage vehicle speeds. Ensure that the horizontal alignment does not result in narrow points in walking and cycling facilities.
  • Vertical curves are to follow the natural grade of the land and/or match adjoining properties. Where vertical curves impact stopping sight distance, employ traffic calming to lower driver speed. For example, reducing speed from 50 to 30 km/h reduces stopping sight distance from 65 to 35 m.
  • Maximum grade of 5%, except in cases of geographical constraints.

 

Medians

Medians can help streamline traffic and ensure safety on higher-speed streets where there is a risk of collisions involving left-turning traffic. In addition, they prevent speeding drivers from crossing into the opposing traffic lane. Medians also provide waiting space for pedestrians and shorten the distance of street crossings.

Medians that extend too far without any opportunities to cross, turn right, or make a U-turn make the other side inaccessible and unnecessarily increase the total distance travelled. They encourage vehicle movement on the wrong side, thereby compromising safety. Hence, the provision of breaks in a median at appropriate intervals is critical.

Design standards  

  • On an artery where the kerb-to-kerb carriageway width is 12 m or wider, a continuous median surmountable by pedestrians (maximum elevation 150 mm) is advised.
  • If the curb-to-curb carriageway width is 11 m or narrower, periodic pedestrian refuges can enhance safety.
  • In order for the median to function as a safe pedestrian refuge, a minimum width of 1 m should be provided. A cycle refuge should be 2 m wide.
  • Guardrails and high kerbs are discouraged because they hinder pedestrian and cycle movement. They should be provided only on carriageways with a kerb-to-kerb width of 18 m or larger, with a break for pedestrian crossing every 50 m.
  • Adjacent to BRT lanes, longer stretches of guardrail can be provided, with breaks at formal crossings (150–200 m).

 

Street trees & landscaping

Landscaping improves the liveability of streets. It plays a functional role in providing shade to pedestrians, cyclists, vendors, and public transport passengers. Effective greening with street trees reduces the street temperature, making it comfortable for people to walk, cycle, or gather for social activities, even during summer afternoons. It also enhances the aesthetic qualities of streets. On a larger scale, plants keep a city cool by reducing the urban heat island effect. Trees also capture dust and remove glare. During storms, they reduce wind velocity. Additionally, trees can help reduce vehicle speeds by reducing the actual or the perceived width of a street.

Design standards

  • Existing trees are to be retained in the course of street improvement projects.
  • Every footpath should have a continuous tree line. Landscaping may extend into bulb- outs in the parking lane but a single tree line should be maintained in order to improve compatibility with underground utility lines. A continuous tree line is preferable to trees placed in the parking lane.
  • Minimum distance between trees to provide continuous shade, depending on the individual trees’ canopy size and shape. A typical interval is 6-10 m between trees.
  • Tree pit locations should be coordinated with the position of street lights.
  • For footpath widths equal or larger than 3.5 m, tree pits should have dimensions of at least 3.5 m by 1.5 m (a minimum of 5 m2) to accommodate the trunk and root structure at full maturity. On narrower sidewalks between 2 m and 3.5 m, 1 m by 3 m tree pits are acceptable and on tree-lined medians, a minimum 1 m width is recommended.
  • Hume pipes can lower the level at which roots spread out, thereby reducing damage to road surfaces and utilities.
  • Trees with high branching structures are preferable.
  • Medium-height vegetation should be trimmed next to formal crossings to improve the visibility of pedestrians and cyclists. f Indigenous species are preferable.

 

Vending

Street vending provides essential goods and services to a wide range of population groups. It also makes public space safer by contributing “eyes on the street,” particularly on streets lined with compound walls. Hence, it is important to provide improved and “formal” street vending areas, especially on major streets and near public transport nodes. Well located street vending reduces trip lengths by allowing people to shop on the way to other destinations. Spaces may be rented out to and managed by cooperatives.

Design standards

  • Street vendors should be accommodated where there is demand for their goods and services—near major intersections, public transport stops, parks, and so on.
  • Supporting infrastructure, such as cooperatively managed water taps, electricity points, trash bins, and public toilets, should be provided.
  • Vending areas should be positioned so as to ensure the continuity of cycle tracks and footpaths. The furniture zone of the footpath or a bulbout in the parking lane are ideal locations for vending.
  • The material used for the vending area should facilitate good drainage.

 

Storm water

Adequate and efficient storm water drainage prevents water logging and erosion. Under- investment in storm water drainage results in major longitudinal storm water flows, which can erode the street surface. Deteriorated surfaces may cause crashes and thus imply costs beyond direct maintenance expenses.

In flooded areas, pedestrians and cyclists are forced to make their way through uncomfortable and potentially dangerous terrain hidden under the water’s surface. After the water drains away, the remaining mud and debris act as a deterrent to walking and cycling.

The design of many streets in Ethiopia places pedestrians and cyclists at the lowest point in the cross section, forcing them to wade through water and mud during the rainy season. Drains are often placed in an ad-hoc manner and are not levelled with the surrounding road surface. Open drain covers cause crashes and pose risks to pedestrians.

Design standards

  • The lowest point in the cross section should occur on the carriageway. Cycle tracks, footpaths, bus stops, and street vending areas should be at a higher level.
  • 1:50 camber for footpaths and cycle tracks.
  • Drain surfaces should be at grade with the surrounding street surface unless provided in landscaped areas. Drain access points should be surfaced appropriately to avoid interrupting pedestrian and bicycle movement.
  • Catch pits should be located at regular intervals, depending on their size and the catchment area, and at the lowest point of the street cross section. Gratings should be designed so that they do not catch cycle wheels.
  • Drainage channels should be provided underground to maximise the area available for NMT.
  • More environmentally benign approaches such as landscaped swales improve groundwater recharge, reduce storm water runoff, and improve the overall liveability of a street. Swales range in size from tree pits and landscaping strips to large low-lying neighborhood parks. Swales are most appropriate on wide rights-of-way with large areas of unused space, but not in constrained environments where they take away space from pedestrians, cyclists, and street vendors.
  • The number of storm water lines in the cross-section should be minimised to keep construction and maintenance costs low. For example, an equal number of catch pits can be accommodated on two instead of four lines if they are placed strategically.
  • Gratings should be designed so that they do not catch cycle wheels.

Underground utilities

Streets are the conduits for major services, including electricity, water, sewage, communication, and gas. The physical infrastructure may occur in the form of pipelines, telephone and fibre optic cables, ducts, and poles. Some utilities, such as telecommunications cables, require frequent access for expansion and maintenance.

Design standards

  • Underground utilities are ideally placed below the parking area or service lane, if present, which can be dug up easily without causing major inconvenience. Where this is not possible, underground utilities can be placed at the outer edge of the right-of-way.
  • Utility boxes should be sited in easements just off the right-of-way to reduce conflicts with pedestrian movement. Where this is not possible, utility boxes should be placed within parking or landscaping areas. If it is absolutely necessary to locate utilities in the footpath, a space of at least 2 m should be maintained for the through movement of pedestrians. Similarly, utility boxes should never constrain the width of a cycle track.
  • Though it is possible to accommodate underground utilities even below a tree line, this may lead to the destruction of the trees and a deterioration in liveability if the utilities need to be uncovered.
  • In order to minimise disruptions, utilities should be installed with proper maintenance infrastructure. For example, telecommunication lines should be placed in ducts that can be accessed at frequent service points.
  • Fire hydrants:
    • Implemented in urban areas with a population of more than 100,000.
    • Positioned in the furnishing zone of streets.
    • Painted red.
    • Height of 60-90 cm.
    • Fitted to the main active and functional water supply line.
    • Location selected by the planning and fire protection agencies.

Street lighting

Well-designed street lighting enables motor vehicle drivers, cyclists, and pedestrians to move safely and comfortably by reducing the risk of traffic crashes and improving personal safety. From a traffic safety standpoint, street lighting is especially important in potential conflict points, such as intersections, driveways, and public transport stops. Additionally, lighting helps road users avoid potholes and missing drain covers. From a personal security standpoint, street lighting is essential for mitigating pedestrians’ sense of isolation and reducing the risk of theft and sexual assault. Improved lighting is particularly important in isolated spaces such as under- and overpasses and walkways next to parks or blank façades.

Design standards

  • The spacing between two light poles should be approximately three times the height of the light fixture.
  • Poles should be no higher than 12 m. Especially in residential areas, they should be significantly lower than 12 m to reduce undesirable illumination of private properties. Additional lighting should be provided at conflict points, such as intersections.
  • The placement of street lighting should be coordinated with other street elements so that trees or advertisement boards do not impede proper illumination.
  • The placement of street lighting can be at either side of the street and/or along the street median, or one-sided at local streets, as per Table 12. For the two-sided layouts, lights should be staggered so as to optimise costs, while still avoiding dark spots, especially for pedestrians.
  • Street lights shall be powered by solar cells and use LED lamps.
  • Lamps should offer sufficient lighting for motor vehicles and NMT areas. For all footpaths, pedestrian-scale lamps should be provided to increase illumination for pedestrians and also beautify urban spaces.

 

Street furniture

Street furniture provides people places to sit, rest, and interact with each other. Street furniture also includes services-related infrastructure, such as trash cans, street vending, toilets, and signage. When positioned on narrow shared streets, benches, tables, street vending spaces, and other furniture can also function as traffic calming elements. Vending stands, tables, roofs, and water taps can support the formalisation of street vending and promote better sanitary conditions. Finally, other street furniture, such as way-finding signs and bus stops, provides information.

Design standards

  • Furniture and amenities should be located where they are likely to be used. Furniture is required in larger quantities in commercial hubs, market areas, crossroads, bus stops, BRT stations, and public buildings.
  • Most street furniture, especially benches and tables, should be placed where it receives shade. Otherwise, it will become too hot to be used during the daytime.
  • Furniture should be located where it does not obstruct through movement. Bulb-outs in parking lanes and street vending islands in shared streets are great places to install furniture. Similarly, a landscaping strip can be broken with street furniture on hardscaped spaces.
  • On streets with large numbers of pedestrians and commercial activity—especially eateries—trash bins should be provided at regular intervals (i.e., every 20 m). On streets with lower pedestrian densities, trash bins can be provided according to adjacent land uses or street activity.
  • Security cameras shall be fitted in important locations at a minimum height of 4.5 m on street light poles.
  • On a 3 m wide footpath, furniture and amenities should be provided sparingly and in the tree line to maintain at least 2 m of clear space for walking.
  • Bulb-outs in a parking lane can accommodate street furniture and amenities without compromising pedestrian mobility.
  • A parking or service lane discontinued in the vicinity of a bus stop provides space for street vending and furniture.
  • On a shared street, furniture can be placed on islands that double as traffic calming elements.

 

 

Street furniture and other street design elements that are static (including utility boxes, street lighting, trees, parking, and liveability bulbouts), need to be aligned in order to leave adequate clear width for the movement of pedestrians, cyclists, and motor vehicles.

(a) On a 3 m wide footpath, furniture and amenities should be provided sparingly and in the tree line to maintain a minimum 2 m clear space for walking.

(b) Bulb-outs in a parking lane can accommodate street furniture and amenities without compromising pedestrian mobility.

(c) A parking or service lane discontinued in the vicinity of a bus stop provides space for street vending and furniture.

(d) On a shared street, furniture can be placed on islands that double as traffic calming elements.

Service lanes

Service lanes improve safety and throughput by segregating property access points and parking from the main carriageway. Service lanes can increase the mobility function of the main carriageway while also maintaining liveability for non-motorised road users. They also reduce interruptions in cycle tracks, and with reduced speeds because of traffic calming, service lanes can function as slow shared spaces.

Service lanes that are too wide encourage fast driving. In addition, wide service lanes invite encroachment by shops, parked vehicles, or street vendors. Therefore, moderate service lane widths are needed to ensure safe user behaviour. In particular, it is difficult to maintain priority for pedestrians on service lanes that are wide enough for two-way car movements. In addition, wide service lanes invite encroachment by shops, parked vehicles, or street vendors.

Design standards

  • A service lane should be 3.0-3.5 m wide for a single lane and 5.5-6.0 m for two lanes.
  • Service lanes should contain traffic calming elements to maintain safe driving speeds.
  • Access into and out of a service lane should be provided via a ramped crossing over the footpath and cycle track, which continue at their original levels.
  • A service lane need not be continuous, lest it become an alternative to the main road.

Bus stops & terminals

Well-designed bus stops offer a comfortable, weather-protected waiting area for public transport passengers while leaving clear space for pedestrian movement behind the shelter. The location of bus stops should be determined considering the land use, street network, and existing passenger behaviour.

Bus bays should be avoided because they increase travel times for public transport users and result in commuters standing in the street while waiting for the bus. However, bus bays may be warranted in some cases where public transport vehicles queue for long periods of time or on undivided carriageways.

Design standards

  • On streets with two or more carriageway lanes per direction, bus stops should be placed adjacent to the bus’s line of travel so that the bus does not need to pull over.
  • On streets with one carriageway lane per direction or at terminal locations, the stop may incorporate a bus bay provided that there is sufficient clear space for walking behind the shelter. The width of the bus bay should be no more than 2.5 m.
  • Bus stops require shelters with adequate lighting; protection from sun and rain; customer information; and clear, paved pedestrian access. Other amenities can include bicycle parking and trash receptacles.
  • Cycle tracks should be routed behind bus shelters.
  • Bus stops should be provided at intervals of 200-400 m.
  • Bus stops may be placed at junctions or mid-block, depending on the route itinerary, transfer opportunities, and passenger origins and destinations. For bus stops near intersections, far side positioning is preferred.
  • Eliminate driveways where they interfere with public transport operations.

 

Street signs and signals

Street signs and signals offer various types of information, including the following:

  • Maximum speed limit for a given street.
  • Directions to different destinations.
  • Intersection operations.
  • Kerb management policies, including parking, no-parking, and loading zones.
  • Temporary street closures.

Design standards

  • Glossy surface to improve legibility at night.
  • Uniform typography with a sans serif typeface above a blue or green background. Where possible, use of symbols is preferred to facilitate understanding regardless of the user’s linguistic background.
  • Convenient position clearly visible to the target users. Signs must not be placed within 1 m of each other or clustered in one location.
  • Traffic lights shall have a minimum height of 4.5 m shall be visible from at least 150 m.
  • Traffic signs placed above pedestrian areas shall have clear height of 2.2 m up to the lower edge of the plate, spacing of at least 0.35 m from the edge of the kerb, and positioning limited to the furniture zone of the footpath.
  • Tourist maps shall be posted in tourist interest areas such as historic areas, public transport stations, and popular public spaces.
  • The clear height of advertisements shall be at least 2.5 m on walls and 3 m on poles.
  • The duration of contracts for temporary advertisement boards shall not be more than 6 months. The owner or city administration shall remove the board within two weeks of notification of expiration of contract to the owner. The duration of contracts for permanent information boards or advertisements is 5 years.

 

Public toilets

Public toilets contribute to the betterment of the urban environment and improve public health. The location of public toilets shall be determined in neighbourhood development plans or urban design plans (access control, plans, street designs, or block designs) and implemented in the construction and furnishing phase of streets. They can also be installed as part of street improvements. Public toilets can be run and managed through micro-scale enterprises to create employment opportunities. Potential funding sources include donations, sponsorships, and advertisements.

Design standards

  • The minimum area to be allocated for public toilets is 50 sq m for a set of male and female stalls and 19.5 sq m for a standalone unisex stall. This includes the toilet facilities and a workstation for access control, collecting fares, supervision, and maintenance.
  • Positioning at public transport stations, public spaces, and other busy locations. 0.8 x 1.20 m.
  • Hygienic, easy to clean, and attractive fixtures. Adequate cleaning to avoid foul smells.
  • Universal access.

On-street parking

In general, valuable street space should be used for wider walkways, trees, cycle tracks, cycle parking, vending, and social gathering space rather than parking. On-street parking may be allowed on streets where all the other requirements for public transport and non-motorised travel have been met.

Design standards

  • Parking areas should be allotted after providing ample space for pedestrians, cyclists, trees, and street vending.
  • Parking bay width of 2.0 m width for taxi stands and 2.2 m in commercial areas.
  • Tree pits can be integrated in a parking stretch to provide shade. Otherwise, shaded
  • street elements, such as footpaths, may be encroached by parked vehicles.
  • Near intersections, parking lanes can be discontinued to reduce conflict and to give additional vehicle queueing space.
  • Dedicated cycle parking should be provided at public transport stops and stations and in commercial districts.
  • In contrast to mobility-oriented elements such as carriageways, cycle tracks, or footpaths, parking involves fewer design constraints as it does not require continuous linear space.

 

Traffic calming

Well-designed traffic calming elements ensure pedestrian and vehicle safety by reducing the speed and potentially also the volume of motor vehicles. The increased use of private vehicles necessitates traffic calming to ensure that streets remain safe for pedestrians and cyclists. Traffic calming elements are particularly important in places where large numbers of children are present, such as schools, parks, and residential areas. Some traffic calming elements, such as speed bumpsand speed tables, are easy to implement, and can be deployed quickly as a solution to road safety challenges.

The effect of any traffic calming measure on all the road users should be carefully considered before they are installed. Some are unsuitable if large buses are part of the traffic stream; some are very harsh on bicycles, motorcycles and motorcycle taxis; and some are totally unsuitable when there is any animal drawn transport.

Design standards

  • Traffic calming can take different forms depending on the context, and is most effective where two or more mechanisms are combined. Traffic calming can be applied near intersections or every 80-120 m in stretches where speeds need to be controlled, such as school zones (streets within 100 m of schools), residential areas, or locations with high foot traffic.
  • Vertical-deflection devices include raised crossings, speed humps, and raised intersections.
  • Speed humps should follow a sinusoidal shape to improve comfort for cyclists.
  • Raised pedestrian crossings should match the level of the adjacent footpath—typically 150 mm. A flat top design is preferred, with allowances for drainage at the kerb. The critical dimension is the ramp slope:
    • 1:6 yields 10 km/h
    • 1:8 yields 15 km/h
    • 1:10 yields 20 km/h
    • 1:12 yields 25 km/h
    • 1:14 yields 30 km/h
  • Rumble strips are uncomfortable for cyclists and should be avoided on urban streets.
  • Horizontal-deflection devices include mini-roundabouts, chicanes, and islands. Design varies but the objective is to reduce speed to 10 km/h below the speed limit.

 

Traffic calming options include horizontal displacement through a meandering carriageway (left) or shared space (middle) and vertical displacement in the form of a speed hump (right).

Construction materials

Construction materials affect the aesthetics, usage, durability, and sustainability of urban streets. The selection of appropriate construction materials shall be based on consideration of the street function and loads along with the material strength, durability, cost, aesthetics, and maintenance needs.

There is strong experience of using local materials in street construction, namely the use of cobblestones for Local Streets. Micro-scale enterprises have good experience in the excavation of rocks from quarries, transport of rocks to sites of production, production of cobblestones, and construction methods.

Design standards

  • Walkways: Concrete is a popular material for walkways because it is durable and requires minimal maintenance. Other materials such as pavers and cobble stones allow for storm water percolation. Footpath materials should be strong and durable. The surface should not be slippery in the rain. Yellow tactile tiles should be included to provide guidance to persons with visual impairments.
  • Cycle tracks: Asphalt is a common material for cycle tracks because it provides a smooth surface for cyclists. Concrete can also be used, but it tends to be more expensive. Some cities use coloured pavement to distinguish cycle tracks from other street elements.
  • BRT: On BRT corridors, the bus lanes are to be constructed in reinforced concrete at stations and intersections. At other locations, use of reinforced concrete is preferred.
  • Carriageways: Construction material of carriageways or vehicle lanes for all streets except local streets shall be concrete asphalt (class C:35) or high-grade multi-layered asphalt concrete, with a potential for upgrading to concrete asphalt over time. For local streets, semi-dressed, dressed or cobblestone, concrete tiles, on compacted and multi- layered aggregate base with strength enough to carry the load of vehicles for daily use and trucks in case of emergency and delivery of goods.
  • Other urban street elements: Street furniture, such as benches, trash cans, and bike racks, can be constructed using materials such as metal, concrete, or wood. Street lighting can be constructed using metal poles and fixtures, with LED bulbs for energy efficiency.

 

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