Observations on Indian Roads

Posted by cartofy on 6 April 2023 in English. Last updated on 2 May 2023.

The OSM Urban Road classification guidelines for India dictate a number of high-level directions on mapping roads in Indian cities. When Devdatta and I tried to fix some classifications in Pune, we realised that the current guidelines don’t provide a solid base for decision making, in an “if X, then Y” way. So we decided to observe, annotate, experiment and retrospect on whether a classification makes sense.

We realised that to map a road, one must understand how a road is perceived, and its purpose in the larger scope of the neighbourhood, locality or city. This gives the road a purpose, and that purpose defines its classification. The purpose or intent of the road is not enough to classify it, so we tried to observe a few other factors that characterise roads in major Indian cities. Here’s what we found.

  1. Much like a river, a road begins somewhere and merges into another road. As roads connect with each other, the larger road essentially “collects” traffic from a smaller road. However, it is not necessary that a smaller road feeds into a larger road. Often, it might feed into a road of the same size, but with elevated purpose.
  2. Some roads serve the same purpose but could vary wildly in their characteristics, including the width of a single lane.
  3. Many collector roads can be easily identified using tell-tale signs such as the presence of speed bumps, traffic signals and dividers.

The observations led us to try and categorise roads based on a few factors:

Class Rank Usually feeds into Definition Lanes in One Direction Traffic Signal Divider Flyovers IMG  
Motorway 1 Trunk/Primary/Motorway Access controlled roads, usually elevated on flyovers and specific entry, and exit points. 2+ n y y 1  
Trunk 1 Trunk/Motorway Sections of the National Highways inside the city. Serve as arterial roads in the same essence as primary roads. 2+ y y y 1  
Primary 1 Primary + Connects major localities and major thoroughfares to travel from one side of the city to another. Usually has multiple lanes and complex junctions. 2+ y y y 1  
Secondary 2 Secondary + Connects two or more neighbourhoods or suburbs, and may serve as a collector for tertiary, residential, and Rank 5 roads. It may feed into other secondary roads. 2+ y y y 1  
Tertiary 3 Tertiary + Serves as a main road within a neighbourhood/suburb. Serves as a collector for residential roads, and other Rank 5 roads. 1-2 n n n 1 2  
Residential 4 Residential+ Narrow road with two way-traffic, generally has houses, residential buildings, offices and amenities, may contain footpaths and parked vehicles on the sides. It may have roundabouts and other junctions. May serve as a collector for Rank 5 roads. 1-2 n n n 1 2 3 4  
Service 5 Residential+ An internal road used to access buildings, typically part of an internal network for housing societies, commercial complexes, warehouses and industrial areas. May have one-ways. Access is typically, but not always, limited. 1 n y n 1  
Living Street 5 Residential+ A narrow road used by pedestrians and two-wheelers, barely allowing two-way traffic. Cars may or may not be allowed, but may not be able to pass due to foot traffic, parked vehicles, and the width of the road. 1 n n n 1  

While the observations may not be empirical, they were helpful in trying to classify roads, especially in Pune and served to enable decision-making during classification. The biggest challenge in India is that every road collection comes with an ‘at time but not always’ clause attached to it. You will find residential roads feeding into state highways, roads narrowing down midway, and other strange occurrences due to land ownership and acquisition issues or just because of poor planning.

We would love community input on these observations so that we can all have better-classified roads.


Comment from adreamy on 23 April 2023 at 10:18

The same goes for South Korea.
The classification of roads(in S. Korea) is very messy due to different interpretations by different contributors.
I think a new common classification should be created and the subcategories should be changed so that each country can categorize according to its own circumstances.
남한도 마찬가지입니다.
기여자들이 제각각으로 해석하는 바람에 (한국의)도로 분류가 아주 엉망입니다.
새로 공통 분류를 만들고 세부 분류는 각 나라의 사정에 따라 부류를 할 수 있도록 바뀌어야 한다고 생각합니다.

Comment from Wilmer Osario on 25 April 2023 at 15:08

(Sorry, my english is not very advanced 😅)

Hello, in Venezuela we are planning something similar. We are working on a standard road classification that easily adapts to the OSM system. That we can also implement throughout our continent, because we have many similarities with neighboring countries.

The way to classify roads is quite a headache 😅, so we tried to build an easy and summarized standard to make easy tagging roads around the world.

Our proposal is based on completely ignoring the physical characteristics of the road, to give priority to its importance, based on the amount of traffic that runs through it or the amount of population that is forced to travel on that road to go from place A to place B.

OSM Latinamerica proposal

In a very general aspect, our proposal could be summarized as follows:

  • Trunk roads form the national highways network that cross an entire country, connecting its most important cities. These highways themselves must connect with other countries in order to create a continental network that allows crossing a continent as directly and quickly as possible.

  • Every road that leads to a city, must be primary, or trunk depending on how important that city is for the country

  • Every road that leads to a town, must be secondary

  • Every road that leads to a village, must be tertiary

  • Every road that leads to a hamlet, must be unclassified

  • Residential roads are all the streets of a city or town that do not have any restriction to transit through them, and that also have no other high priority.

  • If a 4-lanes dual freeway leads to a hamlet of just 100 people, then cannot have a high priority. Because a village of 100 people is not the same as a town of 150,000 inhabitants.

  • If two roads lead to a town, the road with more traffic will have the highest priority, regardless of the conditions on that road.

  • Roads leading to airports, ports and universities are important to only a small portion of the population, so they should not be a high priority.

One of the problems we are having is that there is a notable difference between urban areas and rural areas, because a tertiary road in a small rural town is not the same as a tertiary road in a big city. We have not been able to find a way to unify both concepts.

Another of our problems is that our country is very geographically diverse. There are amazon-jungle regions where the Highway Tag Africa apply better, and other regions where the standard of the rest of the country does not make sense.

Comment from cartofy on 25 April 2023 at 15:37

Thanks for the insights, Wilmer! A few questions: 1. How do you define low, moderate and high traffic? Is it purely via intuition and guesswork or by some metric for classifying traffic? 2. Do you propose to use any topology to make a decision? For example, Road X -> Road Y -> Road Z, within urban and rural areas? 3. What has your experience been with using the highway=unclassified tag? So far, I’ve seen it used as a catch-all tag in India, and its the subject of much debate.

@adreamy - interesting to note that multiple countries seem to have difficulty in conforming to a specific system!

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