Inputs
Example Data Table
| Scenario | Mode | Basis | Time (min) | Speed (km/h) | Detour | Pop Density | Jobs Density |
|---|---|---|---|---|---|---|---|
| Urban infill stop | Walk | Time | 10 | 4.8 | 1.30 | 9,500 | 4,000 |
| Campus connector | Bike | Time | 12 | 14.0 | 1.20 | 6,000 | 2,500 |
| Park-and-ride | Drive | Distance | — | 28.0 | 1.10 | 1,800 | 900 |
Use these examples to sanity-check your assumptions before applying local survey and GIS data.
Formula Used
1) Path length
- Time-based: Path (km) = Speed (km/h) × Time (min) ÷ 60
- Distance-based: Path (km) = Input distance (km)
2) Effective straight-line radius
- Radius (km) = Path (km) ÷ Detour factor
3) Catchment area
- Area (km²) = π × Radius²
- Multi-station net area (km²) = Area × Stations × (1 − Overlap%/100)
4) Demand planning estimate
- Population = Net area × Population density
- Daily boardings ≈ Population × Trips per person × Mode share × Capture rate
- Peak-hour boardings ≈ Daily boardings × Peak-hour share
How to Use This Calculator
- Select the access mode that best matches your site context.
- Choose time-based for early planning, or distance-based for known buffers.
- Set a detour factor to reflect blocks, barriers, and network connectivity.
- Enter densities from local plans, census layers, or GIS summaries.
- Adjust mode share and capture rate using surveys or comparable stations.
- Model multiple stations and apply overlap if buffers intersect.
- Review net area, people, jobs, and boardings to support sizing decisions.
- Download CSV for spreadsheets and PDF for submittals.
Article
Catchment outputs that support construction decisions
Transit catchment figures help teams size access works, set safe pedestrian routes, and coordinate utilities and staging. The effective radius converts time or distance into a straight-line proxy that accounts for real-world detours, barriers, and network connectivity. The resulting area allows quick comparisons across design options, including alternative entrances, temporary closures, and phased openings. When multiple stations are modeled, an overlap discount reduces double counting and keeps early estimates conservative for budgeting and permitting discussions.
Linking density to people, jobs, and activity
Converting area into population, households, and jobs connects mobility planning to site impacts. Higher activity density typically increases footfall, loading demand, wayfinding needs, and requirements for lighting and CCTV coverage. For projects near mixed-use districts, jobs can be a strong indicator of peak directional flows. Use locally sourced density layers where possible, and document assumptions so later GIS updates can be substituted without rebuilding the workflow.
Planning-level ridership from transparent assumptions
The calculator estimates potential daily boardings using trips per person, transit mode share, and capture rate. Mode share reflects broader travel behavior, while capture rate reflects station attractiveness, barriers, and competing stops. Keeping these factors separate helps teams test sensitivity: a small capture change can outweigh large geometry changes in some corridors. Peak-hour share then converts daily potential into a design check for platform width, fare gates, and queue space.
Common field adjustments and quality checks
Detour factor is a practical lever for walkability. Values near 1.00 suit grid networks, while 1.25–1.40 may suit cul‑de‑sacs, arterial crossings, or fenced facilities. If the radius feels too large, first confirm speed and time are realistic for the user group, then increase detour to reflect barriers. Compare net area against known neighborhood extents to avoid overreach, and reduce overlap when stations are spaced closely or share the same access spine.
Example data for a quick sanity check
Example: Walk, 10 minutes, speed 4.8 km/h, detour 1.30, one station. Path = 0.80 km and radius ≈ 0.615 km. Area ≈ 1.19 km². With 9,500 people/km² and 4,000 jobs/km², totals ≈ 11,300 people and 4,760 jobs. Using 2.6 trips, 18% mode share, and 12% capture gives ≈ 636 boardings/day; 25% peak share gives ≈ 159 boardings/hour.
FAQs
1) What does detour factor represent?
It converts network travel to an equivalent straight-line radius. Higher values reflect barriers, indirect streets, crossings, or limited entrances. Use 1.00 only for near-straight access routes.
2) When should I choose time-based versus distance-based?
Use time-based when you know realistic minutes for walking, cycling, driving, or feeder travel. Use distance-based when you already have a buffer distance from plans or mapping.
3) How do I set the capture rate?
Capture rate is the share of potential trips within the catchment that actually use the station. Start with 8–15% for early studies, then refine using comparable stations, barriers, and service quality.
4) Why model multiple stations and overlap?
Projects often include paired entrances or adjacent stops. Overlap reduces double-counting when buffers intersect. If stations are far apart, use a small overlap; if close, increase overlap.
5) Are the boarding results final ridership forecasts?
No. They are planning-level indicators based on transparent assumptions. For forecasts, integrate land use, service frequency, fares, competing modes, and calibrated models or surveys.
6) Which density values should I use?
Prefer local planning layers, census outputs, or GIS summaries for the specific corridor. If using citywide averages, document the source and revisit once parcel-level development data is available.
7) How should I report results in construction documentation?
Export CSV for spreadsheets and audit trails, and PDF for submittals. Include mode, time or distance, detour, densities, and applied overlap so reviewers can replicate the estimate.