Category: Highway Engineering

The trial cycle method asks you to guess a cycle time and check it. Webster’s method does something better — it calculates the cycle time that produces the least delay, directly. That is why it is described as the most rational method of design, and why it appears more often than any other signal design question in GATE, SSC…

Designing a signal means answering one question: how long should the cycle be, and how should it be split between the roads? There are four established ways to answer it. This post covers the list, works through the trial cycle method in full, and then handles pedestrian timing — which every signal design must accommodate. The…

An intersection is where traffic streams want to occupy the same patch of road at the same moment. A traffic signal solves that by allocating time instead of space — each stream gets the whole junction, but only for its own share of the cycle. This post covers what signals are, the three terms you must define…

Signs, signals and painted lines look like three unrelated things. In traffic engineering they are one family, called traffic control devices, and they are grouped not by what they look like but by what job they do. This post covers the definition, why official approval is part of that definition, and the three functional groups. What Counts…

A traffic sign has a hard job. It must be understood in about two seconds, by a driver moving at speed, who may be tired, distracted, or unable to read. It has to work in rain, at night, and for someone who has never travelled that road before. The way engineering solves this is by…

When planners lay out a town’s roads, they are answering one question: what shape should the network be? The answer changes everything — how far people travel, how easy the town is to navigate, how traffic concentrates, and how easily the place can grow. This post covers the six recognised road patterns, what each is…

The Lucknow Plan is the most ambitious of the three twenty-year plans, and the most modern in outlook. It reclassified India’s roads into three systems, set a target nearly three times the previous one, and — for the first time — asked not just how many kilometres of road there should be, but whether every…

The Nagpur Plan achieved its length target. And yet, when engineers looked at the network in 1961, they found it still did not do what the country needed. That gap between hitting the target and solving the problem is what the Bombay Plan set out to address. This post covers why a second plan was needed, its targets, and…

The Nagpur Plan is where Indian road planning stops being an idea and becomes a document with targets, classifications and formulae. Everything you know about road classification — NH, SH, MDR, ODR, VR — starts here. This post covers why the plan was needed, its features, the four classes of road, and both length formulae,…

Open any page of your highway engineering notes and you will find the letters IRC. The camber values are IRC values. The design speeds are IRC design speeds. The maximum superelevation of 0.07 and the lateral friction of 0.15 are IRC figures. This post covers the organisation behind all of them — when it was…