Geometric Design Standards for Urban Roads in Plains (IRC:86-2018) PDF

GEOMETRIC DESIGN STANDARDS FOR URBAN ROADS IN PLAINS IRC:86-2018 INTRODUCTION AND SCOPE Geometric design Implementing IRC 86-1983 Strict adherence to IRC 86- Designing roads solely Updating and adapting to standards play a crucial role...

GEOMETRIC DESIGN STANDARDS FOR URBAN ROADS IN PLAINS IRC:86-2018 INTRODUCTION AND SCOPE Geometric design Implementing IRC 86-1983 Strict adherence to IRC 86- Designing roads solely Updating and adapting to standards play a crucial role leads to the creation of 1983 may increase based on IRC standards new technologies and in ensuring the safety, roads that are durable and construction costs initially. may not always account for innovations may be efficiency, and aesthetics sustainable for urban areas. specific local conditions or challenging within the of urban roads in plains requirements. framework of IRC 86-1983. regions. This presentation will delve into key design considerations and their impact on road performance. FIRST PUBLISHED: 1983 FIRST REVISED: 2018  Urban Expressways are high-speed highways connecting inter-city areas Arterial roads facilitate city-wide mobility and connect long-distance destinations CLASSIFICATION Sub-arterial roads connect neighbourhoods with slightly OF URBAN lower mobility ROADS AND Collector Streets collect and distribute traffic from local STREETS streets Local Streets are low-speed, low-speed streets for local access NMT Streets and Greenways are exclusively for non- motorized traffic, designed with universal accessibility, bicycle parking, and emergency vehicle access DESIGN SPEED The selected speed for designing Proposed Design Speeds (km/h) road sections should logically consider factors like topography, expected operating speed, nearby land use, and the road’s functional classification. SPACE STANDARDS The space standards recommended for the various categories of urban roads are given in table. The term” space standard” is often referred to as “right-of-way” (IRC Manual on Planning and Development of Urban Roads and Streets)  Obstruction Free Min. Walking Zone shall be 1.8 m X 2.2 m - both horizontally & vertically FOOTPATH Footpaths are defined as any area primarily used by ‘all’ pedestrians. They can be adjacent to roadways or away from the road. A footpath should consist of a dead or frontage zone, pedestrian zone and a multi-functional zone (IRC:103). No utility ducts, utility poles, electric water or telecom boxes, trees, signage or any kind of obstruction should be placed within the “Walking Zone” Different Zones of a Footpath (Source: IRC:103)  Frontage Zone or Dead Zone: A dead space in front of active commercial frontage is required for passive slow speed window shoppers clear from the regular pedestrian movement space to avoid conflict and increase the walking space capacity. Pedestrian Zone: An uninterrupted walking zone of minimum 1.8 m (width) and 2.2 m (height) shall be provided. Multi-Functional Zone: A multi-functional zone (also known as a Planting Zone or Street Furniture Zone) of minimum 1-2 m width (depending on the hierarchy of urban road) shall be provided between the pedestrian zone and carriageway The height of a footpath shall not exceed 150 mm above the carriageway. The width of the zone shall be based on the design flows and levels of service outlined in Table Medians and mid- block pedestrian crossings The divider between a two way traffic lane is called median. The maximum height of median kerb is 150 mm. The minimum width of a median should be 1.2 m. Instead of fences, medians should be landscaped and used for storm-water filtration and management wherever possible. Pedestrian crossings will be constructed as raise crosswalks, or painted zebra crossings. Mid-block pedestrian crossings will be located based on the typology of urban road and range from 50-200 m.  Road Width and Design Traffic Volumes The road width should be designed to accommodate the design traffic volume, considering past traffic counts and future urban development. Estimating future traffic volumes can be based on past trends or transportation studies. A 15-20-year design period is recommended for expressways and arterials, and peak hour flows should be 8-10% of average daily traffic. Urban roads in India face mixed traffic conditions, resulting in complex interactions between vehicles. To address this, the capacity of urban roads is expressed as the 'Passenger Car Unit' (PCU), with each vehicle type converted into equivalent PCUs based on size and speed. PCU values vary depending on traffic, roadway, and environmental conditions. The evolved base capacity values, adjustment factors, and Design Service Values (DSV) are used to account for variations in PCU values. Carriageway Width 1. For access roads to residential areas, a lower lane width of 3 m is permissible. 2. Minimum width of urban road without kerb shall be 5.5 m including allowances for a stalled vehicle and pedestrian movement.  The spacing between two light poles shall be approximately three times the height of the pole. Poles shall be no higher than 12 m to reduce undesirable illumination of private properties. Additional lighting shall be provided particularly at black spots, areas of potential risks to Street Lighting women, areas of personal crime, and areas of isolation. A single row of light posts is generally sufficient for streets up to 12 m wide. On wider streets, dual lights can be mounted on a single central post. LATERAL AND VERTICAL CLEARANCES Lateral Clearance: The lateral clearance from the 3. Clearance on divided carriageway edge of pavement should be as follows: The left side clearances should be as above. 1. Pavement without footpath The right side clearance to the face of any structure in the central median shall be as Minimum clearance from the edge of pavement follows: Arterial and sub-arterial road : 1.0 m Arterial and sub arterial road: 1 m from the Collector and local streets: 0.5 edge of pavement 2. Pavement with footpath Collector and local streets: 0.5 m from the No extra clearance beyond the footpath is edge of pavement necessary Vertical Clearance: The minimum vertical clearance on urban roads should be 5.5 m