Notes for engineers
Road survey reference
Standards, class schedules and method notes for Indian survey practice. Written for engineers looking something up rather than for anyone being sold to. The figures are the same ones our own software applies, so you can check our output against them.
- Classes
- 19
- 18 categories plus Other
- Measured against
- 16,560
- hand-counted vehicles
The notes
16 notes. No sign-up, no PDF.
Traffic counts · 12
Class schedules, PCU, count formats and what a count can be trusted for.
PCU values & classes
PCU values as per IRC:64-1990
All 19 canonical classes with the passenger car unit factor each carries, and a worked conversion from a published count.
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Types of traffic survey
Types of traffic survey for a highway DPR
The surveys MoRTH’s DPR terms of reference ask for, with stations, duration, method and output for each, and which of them video can do.
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Traffic volume count for a DPR
The classified traffic volume count, and what a DPR needs
What the deliverable has to contain, which parts recorded video can produce, and the three surveys it cannot.
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TVC format & template
Traffic volume count format, with a template
The layout a classified count is recorded in — 15-minute rows, a column per class, both directions — as a CSV template with the PCU factor for each class.
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AADT & seasonal factors
From a seven-day count to AADT
How a seven-day classified count becomes AADT with seasonal factors per IRC:108-2015, worked through, and what peak hour factor and design hourly volume mean.
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Design traffic in MSA
Design traffic in MSA as per IRC:37-2018
How a classified count becomes cumulative standard axles under IRC:37-2018, worked on the guideline’s own example, and the inputs a count cannot supply.
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Turning movement counts
Turning movement count survey as per IRC:SP:41
What a junction count for a DPR records: the IRC:SP:41-1994 proforma and its PCU factors, which code sets which count duration, and what MoRTH asks for.
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Automated vs manual
Automated counting against manual counting
Manual counting is the reference we are measured against. Four cases where you should not buy this, and the variables that decide the cost.
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Tube vs video counters
Pneumatic tube, infrared or video: choosing a traffic counter
How each counter decides what passed, where each fails in two-wheeler-heavy traffic, and the surveys where a tube counter is the better instrument.
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Evaluating accuracy claims
How to evaluate an ATCC accuracy claim
Seven questions that turn an accuracy percentage into something you can check, with our own answers to each.
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Counting from CCTV
Counting traffic from footage you already have
What makes an existing camera position usable, what pixel height does to accuracy, and why most corridor CCTV was not mounted for counting.
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Drone traffic survey
Drone traffic survey in India: rules, geometry and limits
What the Drone Rules ask of a survey flight, how altitude sets the pixels on each vehicle, and why a battery suits a junction or peak-hour count but not a seven-day one.
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Pavement and roughness · 4
Condition surveys, roughness norms, and where video stops being enough.
Chainage & km stones
Chainage in road surveys: meaning, notation and km stones
What chainage means, how km 361+300 is written, where kilometre and 200 m stones go, and why a km stone, a design chainage and a GPS distance can disagree.
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Distress types & rating
Pavement distress types and condition rating as per IRC:82
The distress types IRC:82-2015 names, its 1-to-3 distress-based rating with the worked example, what the contracts call a PCI, and what video can measure.
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NSV survey
The NSV survey, and what video can do with it
What MoRTH’s circulars require a network survey vehicle survey to record, and which parts recorded video can and cannot produce.
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Roughness: IRI & BI
Road roughness as per IRC: IRI, bump integrator and the limits
IRC:SP:16-2019’s norms and MoRTH’s 2023 contract limits, the conversion between bump integrator mm/km and IRI, and where a phone estimate does and does not fit.
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Why these exist
The same figures our software applies
Every figure in these notes is the figure our software applies, not a rounded version of it. If a PCU total in one of our outputs does not match the schedule published here, one of the two is wrong and we would want to know which.
The same principle runs through how we measure our own error: both accuracy measures published, the stricter one headlined, and the conditions under which ours degrades stated rather than omitted.
Next step
Send us 15 minutes of your footage
- Classified count, per class and per direction
- Annotated verification video
- A note on what your camera position is costing you
No obligation. You keep the output. Back within a working day.