Reference
Turning movement counts for junction design
A turning movement count records, for each arm of a junction, how many vehicles of each class leave by each of the other arms. MoRTH’s DPR terms of reference ask for one at every major intersection, by the method of IRC:SP:41-1994. Here is what that code asks for, which codes set the duration it leaves open, and why a mid-block count’s PCU factors do not carry over.
The terms of reference
What a highway DPR asks for
MoRTH’s standard RFP for DPR consultancy (29 September 2025) lists intersection volume counts and turning movement surveys as two rows of its survey table, both at all major intersections. Only turning movements have a clause of their own, 4.9.4, quoted in full:
- 1“The turning movement surveys for estimation of peak hour traffic for the design of major and minor intersections shall be carried out for the Study. The details regarding composition and directional movement of traffic shall be furnished by the Consultant.”
- 2“The methodology for the surveys shall be as per IRC: SP: 41-1994. The details including location and duration of surveys shall be finalized in consultation with <Agency> officials. The proposal in response to this TOR shall clearly indicate the number of locations that the Consultants wish to conduct turning movement surveys and the rationale for the same.”
- 3“The data derived from the survey should be analyzed to identify requirements of suitable remedial measures, such as construction of underpasses, fly-overs, interchanges, grade-separated intersections along the project road alignment. Intersections with high traffic volume requiring special treatments either presently or in future shall be identified.”
What the report has to show
The feasibility and DPR checklists both carry one line for it: “Traffic surveys for the design of road junctions as per data in IRC: SP:41”. The sample executive summary tabulates each surveyed junction under these headings:
- Existing chainage
- Location
- Total volume, PCU
- Peak hour volume, PCU
- Peak hour
- Intersection type
- Grade separator proposed
Circular 130.265 (2 September 2026) sets what is handed over for turning movement, O-D and axle load surveys: survey point, location, coordinates, chainage, date, time, period of survey and the technique or equipment used, with the data itself.
IRC:SP:41-1994 Table 3.1
One sheet per approach, in vehicles and PCU
SP:41-1994 is still the current edition on IRC’s list of 28 September 2026. Clause 3.1(iii) sets what the count is for: “The peak hour design traffic data should give its compositional and the directional break-up.”
Table 3.1 is a sample proforma for one approach. It names the peak hour, then gives a row for each of ten vehicle groups, five fast and five slow, against columns for the vehicles entering each of the other legs: the number, the PCU equivalency and the PCU. It ends with totals for fast and slow traffic and a count of pedestrians. Every other approach takes its own sheet, and the totals go onto two peak hour flow diagrams, one in vehicles and one in PCU (Figs. 3.1 and 3.2), modified for a junction with three arms or more than four.
At urban and suburban junctions, and near villages with substantial pedestrian movement, SP:41 also asks for the peak hour count of people crossing each arm.
IRC reserves the rights to the publication, so the form is described here, not reproduced; the factors are stated with their row numbers.
| Row | Vehicles | SP:41 | IRC:64 |
|---|---|---|---|
| 1 | Passenger cars, tempos, auto rickshaw, tractors, pickup vans | 1.00 | 1.00 |
| 2 | Motor cycles, scooters | 0.50 | 0.50 |
| 3 | Agricultural tractor, light commercial vehicles | 1.50 | 1.50 |
| 4 | Trucks, buses | 3.00 | 3.00 |
| 5 | Tractor-trailer, truck trailer units | 4.50 | 4.50 |
| 6 | Cycles | 0.50 | 0.50 |
| 7 | Cycle rickshawsDiffers | 1.50 | 2.00 |
| 8 | Hand cart | 3.00 | 3.00 |
| 9 | Horse drawn | 4.00 | 4.00 |
| 10 | Bullock carts | 8.00 | 8.00 |
PCU at a junction
Why a mid-block count’s factors do not carry over
IRC:64-1990 says of its own table: “These factors are meant for open sections and should not be applied to road intersections.” SP:41’s text under Table 3.1 says which to use instead: “For converting vehicles into PCUs, equivalency factors given in Table 3.1 should be used.”
- One row out of ten
- Read row by row, Table 3.1 matches IRC:64-1990 Table 1 for the same vehicle group except cycle rickshaws (1.50 against 2.00), though the groups are worded differently: its first row adds tempos and tractors. In our 19-class schedule that changes Cycle Rickshaw from 2.00 to 1.50.
- Tractors, as printed
- Row 1 lists “tractors” at 1.00 and row 3 an agricultural tractor at 1.50. The table does not say which tractor goes where, so the report should state the choice.
- A third table in Appendix III
- Appendix III gives a capacity method based on the US Highway Capacity Manual, with its own factors: a tractor-trailer unit is 3.00, not 4.50, and small bullock carts 6.00. They belong to that method, not to Table 3.1.
- Roundabouts again differ
- IRC:65-2017 makes PCU at a roundabout depend on its size. From Indo-HCM, its Table 5.2 puts a light commercial vehicle at 1.88 on a 20–30 m roundabout and 1.46 on a 50–70 m one, and a heavy vehicle at 3.65 and 3.05.
Duration
How long to count: every figure has its own code
SP:41-1994 sets no count duration and no recording interval. Each figure in circulation comes from a different code, for a different purpose, and two of those codes have been revised in editions that are not public.
| What to count | For | Code | Edition |
|---|---|---|---|
| The peak hour, by composition and direction. Where peak flows are not available, they may be assumed to be 8 to 10 per cent of the daily flow, split 60:40 | Any at-grade intersection | IRC:SP:41-1994 cl. 3.1, 4.3 | Current |
| Each movement from each approach, by vehicle type, for at least 2 hours in the morning and 2 hours in the evening peak | Signal design | IRC:93-1985 §III cl. 1.1(ii) | Current |
| 2 hours each in the morning and evening peak periods, unless there are extended peak hours | Road junction design | IRC:SP:19-2001 cl. 6.5.1 | Superseded; the revision is not public |
| Counted manually and recorded in 15-minute intervals by lane movement and class; morning and evening peak hours | Junctions on grade-separator studies | IRC:SP:90-2010 cl. 5.6.3 | Superseded; the revision is not public |
| 8 hours of number-plate recording, 4 in each peak | Complex intersections and rotaries | IRC:SP:90-2010 cl. 5.6.3 | Superseded; the revision is not public |
| 24 hours on an average working day, at 15-minute intervals | Urban flyovers | IRC:SP:90-2010 cl. 5.7.1.2 | Superseded; the revision is not public |
| 24 hours over seven consecutive days | Flyovers in open areas | IRC:SP:90-2010 cl. 5.7.1.1 | Superseded; the revision is not public |
| Location and duration agreed with the Agency | A national highway DPR | MoRTH DPR RFP 2025, TOR 4.9.4 | Current |
SP:41 defines the peak hour factor as the “ratio between the number of vehicles counted during the peak hour and four times the number of vehicles counted during the highest 15 consecutive minute”. Computing it needs the count kept in 15-minute bins or finer. That is our reading of the definition, not a recording interval the code states.
What the count feeds
Signals and grade separation, in their own units
A junction count is read against two kinds of threshold: whether a signal is warranted, and whether the junction needs the remedial measures clause 4.9.4 names, up to grade separation.
Signals. The first warrant of IRC:93-1985, still the current edition, is met when, for each of any 8 hours of an average day, the major and minor street volumes reach those in its Table 2. It is in motor vehicles per hour, not PCU; converting it changes the test.
Grade separation. IRC:92-2017 gives, as one of several thumb-rule postulates for an interchange, an at-grade junction that fails “when total traffic of all the arms of intersection exceeds 10,000 PCU per hour”. It is an example in a list, not a threshold that decides the case alone.
| Lanes, major | Lanes, minor | Major, both approaches | Busier minor approach, one way |
|---|---|---|---|
| 1 | 1 | 650 | 200 |
| 2 or more | 1 | 800 | 200 |
| 2 or more | 2 or more | 800 | 250 |
| 1 | 2 or more | 650 | 250 |
Where Playcraft fits
How the codes count, and what we build
The codes that describe a method describe people. IRC:SP:19-2001 suggests enumerators on each arm of a simple junction, and a licence plate survey at multi-legged junctions and rotaries; IRC:SP:90-2010 says turning counts “should be conducted manually”, while allowing automatic counters for the classified volume count. Both are superseded by revisions that are not public. None of the codes we read mentions video for turning counts, and clause 4.9.4 names no technology. That is not a prohibition, and we do not read it as permission either.
Shipped: Playcraft ATCC counts classified traffic crossing a line, from recorded video, by direction and in 15-minute intervals, with PCU per IRC:64-1990. That is an open-section count.
Built on demand: a turning movement count from junction video, following each vehicle from the arm it enters to the arm it leaves and reporting it per approach with Table 3.1’s factors and the flow diagrams. We build it on demand. Our published 95.0% by volume and 92.1% by weighted class are for a counting-line count; a turning count also depends on keeping each vehicle’s identity from entry to exit, which that test does not measure. Check it against a hand count at your junction before relying on it.
Not ours: the pedestrian counts SP:41 asks for at urban junctions. See also the traffic surveys a DPR asks for and PCU values as per IRC:64-1990.
Sources
- IRC:SP:41-1994, Guidelines for the Design of At-Grade Intersections in Rural & Urban AreasIndian Roads Congress · cl. 1.3.2, 3.1, 4.3, 5.2.2, 7.4.2; Table 3.1; Appendix III · September 1994, reprinted 2011
- Revised RFP for consultancy services for preparation of Detailed Project ReportsMoRTH · Circular 130.247, Terms of Reference cl. 4.9.1, 4.9.4; DPR checklists; Appendix VIII · 29 September 2025
- IRC:64-1990, Guidelines for Capacity of Roads in Rural Areas (First Revision)Indian Roads Congress · cl. 7.1; Table 1 · 1990
- IRC:93-1985, Guidelines on Design and Installation of Road Traffic SignalsIndian Roads Congress · §III cl. 1.1, 3.1; Table 2 · December 1985
- IRC:92-2017, Guidelines for the Design of Interchanges in Urban Areas (First Revision)Indian Roads Congress · cl. 4.5.6, 7.1 · November 2017
- IRC:65-2017, Guidelines for Planning and Design of Roundabouts (First Revision)Indian Roads Congress · cl. 5.2; Table 5.2 · 2017
- IRC:SP:90-2010, Manual for Grade Separators & Elevated StructuresIndian Roads Congress · cl. 5.6.2–5.6.3, 5.7.1.1–5.7.1.2; superseded by the 2023 revision, not public · November 2010
- IRC:SP:19-2001, Manual for Survey, Investigation and Preparation of Road ProjectsIndian Roads Congress · cl. 6.5; superseded by the 2020 edition, not public · 2001
- List of IRC publicationsIndian Roads Congress · S.No. 46, 47, 75, 76, 126, 146, 194 · 28 September 2026
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