Modal Shift & Commute Emissions Simulator

Daily Commute Trips

Trips per day 20,000

Average trip length 9.0 km

Mode Share

Petrol car 40%

Electric car 15%

Bus / transit 25%

Bike / walk 20%

Sliders auto-normalise to 100% — moving one rescales the others proportionally.

Mode Mix

Live Impact

Daily CO₂ emissions

— kg/day

Energy / trip

— kWh

Congestion index

—

How it works

Each trip's emissions come from a per-passenger-km factor for its mode. Total daily CO₂ is the sum across modes:

CO2_day = Σ_mode share_mode · trips · dist · EF_mode

EF (g CO2 / passenger-km):
  petrol car   192   (tailpipe, ~1.5 occupants)
  electric car  53   (grid-average generation mix)
  bus           82   (diesel bus, shared across riders)
  bike/walk      0

Energy per trip uses each mode's real-world consumption (car ≈0.6 kWh-equiv/km, EV ≈0.18 kWh/km, bus ≈0.25 kWh/passenger-km, bike/walk ≈0), averaged by the current mix.

Road congestion follows the Bureau of Public Roads (BPR) function, using only car+EV volume V against fixed road capacity C — buses and bikes barely add to it:

t(V) = t0 · (1 + 0.15·(V/C)^4)
V = (share_car + share_ev) · trips  (car-equivalent volume)

Congestion index below is t(V)/t0 − 1, i.e. the percentage delay above free-flow travel time. Shifting trips from car/EV to bus or bike lowers V with the fourth power — small mode shifts near saturation produce outsized congestion relief, exactly as BPR predicts for real road networks.

Petrol car Electric car Bus Bike / walk

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