Road margins is an inevitable topic everyone should know who are into transportation engineering. We will see the different types of road margins, the details about the right of way on road and the formation width of road as per irc in the blog. I will also walk you through shoulder of the road being an important road margin.
- What are road margins?
- Road margin types
- Formation width of road as per irc
- Right of way on road
- Conclusion
What are road margins?
The portion of the road beyond the carriageway and on the roadway can be generally called road margins. Different elements of road margins are shoulder, parking lanes, bus bays, cycle track, footpath and guard rails. Let’s get into each one of them and learn in detail.
Road margins are essential components of highway design, serving various functions to enhance safety and efficiency. They include areas adjacent to the roadway such as shoulders, sidewalks, footpaths, road verges, berms, and medians. These elements provide space for emergency stops, pedestrian pathways, drainage control, and separation of traffic lanes. Properly designed road margins contribute to the overall functionality and safety of highways, accommodating diverse users and environmental conditions.
Road margin types
Road margins are essential components of highway design, enhancing safety and functionality. Here are the main types:
- Shoulder of the road
- Parking lane
- Bus bays
- Cycle track
- Footpath
- Guardrails
We’ll cover each type one by one to provide a comprehensive understanding.
Shoulder of the road-important among road margins
A shoulder is an emergency stopping lane by the verge of a road or motorway, on the right side in countries which drive on the right, and on the left side in countries which drive on the left. Shoulder of the road is provided along the road edge.
The shoulder of the road is a crucial element among road margins, providing a safety buffer for vehicles to stop during emergencies. It offers additional space for cyclists and pedestrians, enhancing overall road safety. Shoulders also support the structural integrity of the pavement and facilitate drainage, preventing water accumulation on the roadway. Regular maintenance of shoulders ensures they remain effective, contributing to the smooth operation and longevity of the road infrastructure.
Also read: Bitumen for road- Grade and properties of bitumen
The main objectives of the shoulder of the road
The main objectives of shoulders are,
- The accommodation of stopped vehicles
- They serve as an emergency lane for vehicle
- Shoulders of the road provide lateral support for base and surface courses
A shoulder of the road should be strong enough to bear the weight of fully loaded truck even wet conditions. The shoulder width should be adequate for giving working space around a stopped vehicle. It is desirable to have a width of 4.6m for the shoulders. Minimum width of 2.5m is recommended for 2 lanes rural highway in India.
That’s it about shoulder of the road. Next, let’s see about parking lanes.
Parking lanes
Parking lanes are designated areas adjacent to roadways where vehicles can be parked temporarily or for extended periods. Parking lanes are provided in urban lanes for side parking. Parallel parking is preferred because it is safe for side parking. Parking lanes should have minimum of 3m width in the case of parallel parking.
They help manage traffic flow by keeping parked cars off the main travel lanes, thus reducing congestion. Properly marked and managed parking lanes enhance road safety, improve access to businesses and residences, and provide organized parking solutions in urban areas.
Bus bays
A bus bay, otherwise called bus turnout, bus pullout, off-line bus stop is a designated spot on the side of a road where buses may pull out of the flow of traffic to pick up and drop off passengers. It is often indented into the sidewalk or other pedestrian area. They are provided so that they don’t obstruct the movement of vehicles in the carriageway. But at the cost of the time necessary to merge back into flowing traffic.
Cycle track
A Cycle_track, otherwise called separated bike lane or protected bike lane is an exclusive bikeway that has elements of a separated path and on-road bike lane. They are provided in urban areas when the volume of cycle traffic is high. Minimum width of 2m is required.
Footpath
A footpath is a type of thoroughfare that is intended for use only by pedestrians and not other forms of traffic such as motorized vehicles, cycles, and horses. They can be found in a wide variety of places, from the center of cities, to farmland, to mountain ridges. Urban footpaths are usually paved, may have steps, and can be called alleys, lanes, steps, etc. Footpaths are for pedestrians, especially in urban areas. Minimum width should be 1.5m.
Also read: Applications of Intelligent transportation system- everything you want to know
Guard rails
They are provided at the shoulder of the road. Various designs of guard rails are there. Guard rails painted in alternate black and white are usually used. They also give better visibility of curves at night.
Guard rails are safety barriers installed along roadways to prevent vehicles from veering off the road or into hazardous areas. They absorb impact and redirect vehicles, reducing the risk of severe accidents and enhancing overall road safety.
So, we have seen the main road margins. Its time to look into some terms related to them.
Formation width of road as per irc
Formation width of road as per irc (The Indian Road Congress) or roadway width is the sum of width of pavement or carriageway including separators and shoulder of the road.
According to the Indian Road Congress (IRC) standards, the formation width of a road refers to the total width required to accommodate the roadway and its components. It includes the width of the pavement or carriageway, which is the portion of the road where vehicles travel, and the shoulders, which are adjacent strips of land providing safety and support.
Additionally, formation width encompasses separators or medians, which are central areas separating opposing traffic flows to prevent collisions and manage traffic effectively. This comprehensive width ensures that the road can safely handle the intended traffic volume and type, provides space for emergency stops, and supports drainage and other road infrastructure. The design of the formation width takes into account factors such as traffic volume, road classification, and safety considerations, ensuring that roads are both functional and safe for users. Width of formation for various class of roads (IRC) are:-
Right of way on road
Right of way on road otherwise called land width is the width of land acquired for the road, along its alignment. It should be adequate to accommodate all the cross-sectional elements and may reasonably provide for future development. To prevent ribbon development along the highways, control lines and building lines may be provided.
Also read: Intelligent transportation system: A comprehensive approach to its components
The figure below shows the right of way on road for different type of roads.
Got every detail about road margins and related terms? Let me know your doubts and feedbacks in the comments.
Key Takeaways of Road Margins
- Road Margins: Essential components of highway design that enhance safety and functionality.
- Shoulders: Provide emergency stopping space, structural support, and aid in drainage.
- Parking Lanes: Manage traffic flow by keeping parked vehicles off main lanes, enhancing road safety.
- Bus Bays: Allow buses to pick up and drop off passengers without obstructing traffic flow.
- Cycle Tracks: Dedicated paths for cyclists, improving safety and accommodating high cycle traffic.
- Footpaths: Designated pathways for pedestrians, ensuring safe movement in urban areas.
- Guard Rails: Safety barriers that prevent vehicles from veering off the road and reduce the risk of severe accidents.
- Formation Width: Total width of the road including pavement, shoulders, and separators, as per IRC standards.
- Right of Way: Width of land acquired for the road, ensuring adequate space for road elements and future development.
Conclusion
In transportation engineering, road margins play a crucial role in enhancing road safety and functionality. They encompass shoulders, parking lanes, bus bays, cycle tracks, footpaths, and guard rails, each serving specific purposes. Shoulders are essential for emergency stops and structural support, while parking lanes and bus bays improve traffic flow and safety. Cycle tracks and footpaths ensure safe pathways for non-motorized users, and guard rails prevent vehicles from veering off the road. Properly designed road margins contribute significantly to the overall efficiency and safety of highways. A thorough understanding of these elements is essential for developing effective road infrastructure that meets diverse needs and environmental conditions.
MUST READ: Classification of roads-5 types of roads full details
Happy learning!
vin civilworld 
