The method provided in IRC:93-1985 calculates pedestrian green time as T = 7 + W/1.2 seconds, where W is the carriageway width in metres. For a 12 m crossing, the calculation is 7 + 12/1.2 = 17 seconds. This explains the assumptions in that 1985 document; check the latest requirements of the responsible road authority before using any value in a real signal design.
This article focuses on the calculation. For the basic meaning and classification of crossings, see CivilEase's pedestrian crossing definition and classification.
Formula for pedestrian green time in IRC:93-1985
The IRC:93-1985 method is:
Pedestrian green time, T (s) = 7 + W (m) / 1.2 (m/s)
- W is the width of carriageway the pedestrian must cross, in metres.
- 1.2 m/s is the assumed pedestrian walking speed in this method.
- 7 seconds is the additional pedestrian reaction time specified in the document.
- T is the resulting green interval, in seconds, under those assumptions.
The units work because metres divided by metres per second gives seconds. The IRC text describes dividing the carriageway width by 1.2 m/s, then adding 7 seconds to obtain the green time allotted for the pedestrian phase.
Worked example: 12 m crossing
A pedestrian crosses a 12 metre road. At 1.2 metres per second, the crossing takes 10 seconds. Adding the 7-second allowance in IRC:93-1985 gives 17 seconds.
Crossing width W = 12 m
12 / 1.2 = 10 s walking time; 10 + 7 s allowance = 17 s total.
Quick table for common crossing widths
The following values apply only when using the same 1.2 m/s speed and 7-second allowance:
| Crossing width W | Walking time W/1.2 | Green time 7 + W/1.2 |
|---|---|---|
| 6 m | 5 s | 12 s |
| 9 m | 7.5 s | 14.5 s |
| 12 m | 10 s | 17 s |
| 15 m | 12.5 s | 19.5 s |
These are arithmetic results, not universal timings to copy into a controller. Apply the rounding and display rules required by the responsible authority and the signal controller; do not round a required time down.
How to measure the crossing distance
Use the path a pedestrian actually has to walk through the signal-controlled crossing. IRC:93-1985 describes the width of carriageway to be crossed. At a real junction, the painted crosswalk, curb lines, skew angle, median, refuge island, and signal stages can make the usable crossing path different from a lane-count estimate.
For a divided road, do not automatically halve the full width just because a median is present. Treat each half as a separate stage only when the refuge and signal operation actually allow a pedestrian to stop there safely and continue on a later indication. Otherwise, calculate for the full crossing movement and verify the layout against the governing design guidance.
Why another source may give a different answer
IIT Bombay's NPTEL traffic-signal lecture presents the more general form Gp = ts + dx/up: start-up lost time plus crossing distance divided by walking speed. It describes using a pedestrian speed around the 15th percentile and gives 4.7 seconds as an assumed start-up lost time in its example.
That is a different set of assumptions from IRC:93-1985's 7-second allowance. For a calculation, choose the method required by the applicable design standard and use its terms consistently. Do not add 7 seconds and 4.7 seconds together.
Checks before applying the calculation to a real signal
- Confirm the governing document. IRC:93-1985 is an older publication. The IRC catalogue updated in July 2025 still lists that edition, but a catalogue entry alone does not prove that no newer local rules, amendments, or project specifications apply. Confirm the requirements with the responsible authority.
- Check who uses the crossing. A fixed assumed speed may not represent older adults, children, people with disabilities, or a crowded crossing. Use field observations and the applicable standard's design-speed method where required. NPTEL's formulation specifically points to a lower-percentile pedestrian speed rather than assuming every user walks at the average.
- Check the complete signal operation. A calculation of pedestrian green time does not by itself set the full cycle, vehicle greens, change intervals, clearance intervals, or the exact WALK and clearance indications. Check phase conflicts and the whole junction timing plan.
- Verify the site geometry and operation. Confirm the crossing path, curb ramps, refuge arrangements, visibility, and signal indications in the field. Recheck the timing after changes to the road layout or signal phasing.
IRC:93-1985 itself notes that cycle length should allow adequate pedestrian clearance as well as account for other intersection needs. The width formula is therefore one calculation within a wider engineering design.
Common mistakes
- Using a width in feet with a walking speed in metres per second.
- Leaving out the 7-second allowance when specifically applying the IRC:93-1985 method.
- Adding the IRC 7-second allowance to the separate 4.7-second NPTEL assumption.
- Calling 1.2 m/s a safe speed for every pedestrian group or every location.
- Confusing the calculated pedestrian green interval with the WALK indication or clearance display on a particular controller.
- Using this short calculation as a complete signal design without checking phases, vehicle timing, site conditions, and current local requirements.
Frequently asked questions
What is the formula for pedestrian green time in IRC:93-1985?
For crossing width W in metres, the method is T = 7 + W/1.2 seconds. The 1.2 m/s walking-speed assumption and 7-second reaction allowance are those stated in the older IRC document.
What is the pedestrian green time for a 9 m crossing?
Using the same formula: 7 + 9/1.2 = 7 + 7.5 = 14.5 seconds. A real signal should follow the applicable authority's timing and rounding requirements.
Is pedestrian crossing time just width divided by walking speed?
That division gives the walking portion of the calculation. The IRC:93-1985 method adds 7 seconds. Other engineering methods express the allowance as a start-up term and may use different values, so follow the governing source rather than mixing formulas.
Is 1.2 m/s the correct speed for every crossing in India?
No single value should be treated as suitable for every site and every user group. It is the assumed speed in the IRC:93-1985 calculation described here. Check the currently applicable design guidance and consider observed pedestrian speeds and vulnerable users.
Does a median always divide the crossing distance in half?
No. A median changes the calculation only when it functions as a safe refuge and the signal arrangement provides a valid separate crossing stage. Confirm the geometry and signal operation before treating the legs separately.
Sources
- Indian Roads Congress, IRC:93-1985, Guidelines on Design and Installation of Road Traffic Signals — see Section 22.1 and Appendix 2. This link is a reproduced copy of the document.
- Indian Roads Congress, Catalogue of IRC Publications (updated 14 July 2025) — lists IRC:93-1985.
- Tom V. Mathew, IIT Bombay/NPTEL, “Special Requirement in Traffic Signal,” pedestrian crossing section — gives the general start-up-plus-crossing-time form and its stated assumptions.
Educational explanation only. Signal timings for public roads must be checked and approved under the standards and procedures applicable to the specific road authority and site.
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