Skybridge Pedestrian Flow Calculator

Calculator Inputs

Large screens: 3 columns · Small screens: 2 · Mobile: 1

Calculation basis

Choose whether you know hourly demand or observed occupancy.

Bridge length (m)

Clear width (m)

Edge clearance each side (m)

Accounts for railings, shy distance, and buffers.

Obstruction width (m)

Kiosks, columns, signs, or temporary barriers.

Utilization factor (0.50–1.00)

Represents uneven use and local pinch points.

Average walking speed (m/s)

Speed adjustment (0.70–1.10)

Use for crowd behavior, luggage, or control measures.

Surface condition

Grade (%)

Range limited for practical pedestrian facilities.

Major direction split (%)

50 means balanced two-way; 100 means one-way.

Peak hour factor (0.70–1.00)

Lower values indicate sharper surges within the hour.

Hourly demand (ped/h)

The calculator applies PHF to obtain peak-adjusted demand.

Observed occupancy (ped)

Estimated number of pedestrians on the bridge at once.

Reset How to use Formula used Example table Article FAQs

Tip: Set major split to 100% to approximate one-way operation.

How to use this calculator

Choose a calculation basis: hourly demand or observed occupancy.
Enter skybridge geometry, including clearances and obstructions.
Set walking speed, surface condition, grade, and directional split.
Provide a peak hour factor to reflect surges within the hour.
Click Calculate to view LOS, capacity, and V/C ratio.
Use Download CSV or Download PDF after results appear.

Formula used

Geometry

W_e = (W - 2C - O) × U
A = W_e × L

W = clear width, C = edge clearance each side, O = obstruction width, U = utilization factor, L = length.

Speed, density, and flow

v = v_avg × S_adj
k = N / A (occupancy mode)
k = Q / (v × W_e × 3600) (demand mode)
q' = v × k
Q = q' × W_e × 3600

k in ped/m², q' in ped/(m·s), Q in ped/h.

Capacity and utilization

q'_cap = 1.60 × F_surface × F_grade × F_conflict
Q_cap = q'_cap × W_e × 3600
V/C = Q_design / Q_cap
Q_design = Q_hour / PHF (demand mode)

Conflict factor is a practical estimate: highest reduction near 50/50 two-way balance.

Level of Service (LOS)

LOS is assigned from density (ped/m²):

LOS	Density (ped/m²)	Interpretation
A	≤ 0.31	Free movement, high comfort
B	0.31–0.43	Minor interactions
C	0.43–0.72	Noticeable interactions
D	0.72–1.08	Restricted passing
E	1.08–1.63	Very constrained movement
F	> 1.63	Unstable flow, queueing likely

Example data table

These examples illustrate typical inputs and outputs. Actual values depend on design context and operational controls.

Case	L (m)	W (m)	W_e (m)	Mode	Demand / Occupancy	Speed (m/s)	Density (ped/m²)	Flow (ped/h)	Cap (ped/h)	LOS
Commuter peak	45	4.00	3.06	Demand	1800 ped/h	1.30	0.140	2000	14065	A
Event surge	60	3.50	2.13	Demand	2600 ped/h	1.09	0.389	3250	8020	B
Observed crowd	40	5.00	4.18	Occupancy	260 ped	1.19	1.555	27788	19524	E

Try the first example by clicking Calculate with default inputs.

Effective width drives usable capacity

Throughput is governed by effective width, not architectural clear width. The tool subtracts edge clearances for railing shy-distance, then removes obstruction width. A utilization factor reduces width to reflect uneven use near doors, turns, or pinch points. Increasing effective width usually improves capacity almost linearly and lowers density for the same demand.

Peak hour factor converts hourly totals into design flow

Arrivals are rarely uniform. A peak hour factor (PHF) below 1.00 indicates a sharper within-hour surge. The calculator divides hourly demand by PHF to estimate a peak-adjusted design flow, then uses it for density and V/C. Lower PHF values should be used when crowds arrive in waves from transit platforms, event releases, or signal timing.

Two-way balance reduces performance near 50/50

Opposing streams create passing conflicts and lateral friction. The directional split input applies a conservative conflict factor, with the greatest reduction at balanced two-way flow and minimal reduction near one-way conditions. If operations allow, temporary one-way management can improve stability and user comfort during peak periods.

Surface and grade modify walking efficiency

Surface condition and grade influence confidence and pace. Wet or slippery finishes reduce specific capacity, and uphill grades reduce performance further. If sustained grades exceed 5%, consider landings, better traction, and clear drainage to protect safety while preserving movement.

Use density-based LOS to communicate user experience

LOS is assigned from density bands. LOS A–C supports comfortable passing, while LOS E–F indicates constrained movement where queues and stop-and-go behavior may appear. Combine LOS with V/C: poor LOS plus high V/C is a strong trigger for widening, access control, or schedule-based demand management.

Example data snapshot

Scenario	Effective width (m)	Demand (ped/h)	PHF	Density (ped/m²)	LOS
Commuter peak	3.06	1800	0.90	0.42	B
Event surge	2.21	2600	0.80	1.33	E

FAQs

1) What does effective width represent?

It is the usable walking width after subtracting edge clearances and obstructions, then applying a utilization factor. It better reflects real movement space than architectural clear width.

2) Why does PHF increase the design flow?

PHF accounts for within-hour surges. When PHF is below 1.0, the same hourly total is concentrated into shorter peaks, so peak-adjusted design demand becomes higher.

3) How is LOS determined in this tool?

LOS is assigned from pedestrian density bands (ped/m²). Lower densities generally mean freer movement and higher comfort, while higher densities indicate constrained movement and potential queueing.

4) What does the V/C ratio indicate?

V/C compares design flow to estimated capacity. Values above 1.0 suggest demand exceeds capacity. Values near 0.85–1.0 indicate limited buffer for surges, incidents, or slower users.

5) How should I choose walking speed?

Use observed speed if available. For planning, 1.2–1.4 m/s is typical for adults. Reduce speed for luggage, elderly users, restricted visibility, or crowd control, using the speed adjustment factor.

6) Does two-way balance matter?

Yes. Near 50/50 opposing flow, interactions increase and effective capacity drops. If operations allow, one-way management during peaks can improve stability and comfort without physical widening.

7) Can I use occupancy mode for design?

Occupancy mode is best for monitoring or validation when you can estimate people on the bridge. For design sizing, demand mode is preferred because it links directly to arrivals and peak factors.