Calculator inputs
Example data table
| Scenario | Route (km) | Max walk (m) | Cruise (km/h) | Target (km/h) | Dwell (s) | Penalty (s) | Peak pax/stop | Headway (min) |
|---|---|---|---|---|---|---|---|---|
| Urban mixed-traffic | 10 | 350 | 30 | 18 | 22 | 14 | 7 | 8 |
| Suburban arterial | 18 | 450 | 45 | 25 | 18 | 10 | 4 | 12 |
| Campus circulator | 5 | 250 | 20 | 14 | 25 | 8 | 10 | 6 |
Formula used
1) Coverage-based spacing
If the maximum acceptable walk distance is W, a common first-pass spacing is:
S_walk = 2 × W
2) Speed-based stop limit
Run time between stops uses the cruise speed V_r:
T_run = (L / V_r) × 3600
Per-stop time combines dwell, acceleration loss, and boarding:
T_stop = dwell + penalty + (pax × board_time)
A commercial speed target V_c gives a time budget:
T_budget = (L / V_c) × 3600
3) Recommended spacing
The tool blends coverage and speed constraints (or uses your chosen policy) to produce a recommended total stop count, then:
S_rec = L / (N − 1)
How to use this calculator
- Enter the corridor length and maximum walk distance for access goals.
- Set cruise speed and a commercial speed target that reflects service goals.
- Add realistic dwell, accel/decel penalty, and peak boarding assumptions.
- Choose a policy: coverage-focused, speed-focused, or balanced.
- Press Submit to view spacing, stop count, and offsets.
- Use Download CSV or Download PDF to share outputs.
Access coverage benchmark
When maximum walk distance is 400 m, a two‑sided catchment suggests 800 m spacing. On a 12 km corridor, that yields about 16 stops including terminals. Many agencies tighten to 300–350 m in dense grids, which moves spacing toward 600–700 m and increases stop count by roughly 15–25%.
Commercial speed trade-off
Commercial speed combines cruise time and per‑stop time. With cruise 35 km/h, 12 km needs about 20.6 minutes of pure running. If per‑stop time is 47 s, 16 stops add 12.5 minutes, producing ~24.0 km/h. Raising stop count to 22 under the same assumptions drops speed near 20 km/h, which is often the threshold for reliability.
Dwell time sensitivity
Dwell is highly variable: off‑board fare collection, all‑door boarding, and level boarding can cut dwell from 20 s to 10–12 s. At 16 stops, saving 8 s each removes 2.1 minutes from the trip and increases commercial speed by about 1.6 km/h. In peak periods, boarding time per passenger is the dominant lever.
Spacing policy interpretation
Coverage-focused spacing prioritizes access even if speed falls. Speed-focused spacing caps stops to protect travel time, which benefits through riders and schedule adherence. Balanced mode blends both, typically landing between the walking-based stop count and the speed-based maximum. If you enter a target stop count, the calculator uses it while still respecting the speed constraint when feasible.
Capacity proxy check
Headway converts vehicle capacity into hourly capacity. With 10‑minute headway, service provides 6 trips/h. At 70 passengers, that is 420 pax/h per direction. If your peak boarding proxy implies 520 pax/h, the load factor exceeds 1.0, indicating crowding risk. Reduce headway, use larger vehicles, or revisit boarding assumptions.
Using offsets for field implementation
The stop offset table converts average spacing into buildable chainage points. Use offsets to align stops with safe crossings, curb geometry, and transfer nodes, then accept moderate spacing variation. Keep near‑side or far‑side placement consistent at signals, and document exceptions so schedules and passenger information remain accurate. A site audit before construction helps confirm visibility, drainage, and ADA boarding clearances for each location.
FAQs
1) What spacing should I start with for an urban corridor?
Start from access: use two times the maximum walk distance. Then test speed impacts with your dwell and boarding assumptions, and adjust using the policy that matches your service goals.
2) Why does the calculator use a two‑sided catchment?
Most riders approach from both sides of a stop along a corridor. Using two times walk distance approximates the midpoint between adjacent stops under typical linear access conditions.
3) How do I estimate boarding time per passenger?
Use observed peak conditions. Cash payments and single‑door boarding increase seconds per passenger, while off‑board payment and all‑door boarding reduce it. Keep values conservative for planning.
4) What does “commercial speed” include?
It includes running time plus all stop-related time: dwell, acceleration/deceleration loss, and boarding effects. It is the speed riders experience from terminal to terminal.
5) What if my target commercial speed is not feasible?
If the time budget is below pure running time, no stop pattern can reach the target. Raise the target time, increase cruise speed assumptions, or reduce corridor length for the segment studied.
6) How should I use the stop offset table?
Treat offsets as a starting geometry. Shift stops to safe locations, then recheck spacing and speed. Small deviations are acceptable; document changes so schedules and maps stay consistent.