| Scenario | Daily Trips | Peak Factor | Inbound | Light | Medium | Heavy | Bus | Equipment |
|---|---|---|---|---|---|---|---|---|
| Concrete Pour Day | 650 | 12% | 60% | 40% | 18% | 32% | 5% | 5% |
| Typical Weekday | 420 | 10% | 55% | 55% | 20% | 15% | 5% | 5% |
| Finishing Phase | 300 | 9% | 52% | 70% | 15% | 8% | 5% | 2% |
- PeakHourTrips = TotalDailyTrips × (PeakHourFactor ÷ 100)
- ModeDailyTrips = TotalDailyTrips × (ModeShare ÷ 100)
- ModePeakTrips = PeakHourTrips × (ModeShare ÷ 100)
- InboundTrips = Trips × (InboundShare ÷ 100)
- OutboundTrips = Trips − InboundTrips
- Enter the total daily trips for the site access plan.
- Set the peak hour factor to match observed peak operations.
- Choose an inbound share that reflects arrival patterns.
- Assign realistic vehicle shares for your project phase.
- Submit to view totals, mode split, and directional breakdown.
- Download CSV for spreadsheets or PDF for field distribution.
Trip totals and access capacity
Daily trip totals translate into gate queues, laydown congestion, and haul-route exposure. Start with a defensible count from worker rosters, delivery logs, and equipment moves. For example, 420 trips per day can mean 210 arrivals and 210 departures when directions are balanced. If your plan limits gate processing to 60 vehicles per hour, the total must be supported by staggered shifts and scheduled delivery windows.
Peak hour factor selection
The peak hour factor converts daily volume into the busiest operating hour. A 10% factor yields 42 peak-hour trips from 420 daily. Use higher values during concrete pours, major lifts, or constrained access periods. If security checks add 45 seconds per vehicle, 42 peak trips require about 32 minutes of processing on one lane; add a second lane or adjust arrival timing.
Mode share calibration by phase
Vehicle mix changes by project stage, so mode shares should be reviewed weekly. Earthworks typically increase heavy truck share, while fit-out increases light vehicles and small vans. When shares do not sum to 100%, proportional normalization prevents distorted outputs while preserving relative proportions. Pair shares with parking and staging limits: a 32% heavy share on a 650-trip pour day implies 208 heavy movements to route and time.
Directional split and gate staffing
Inbound percentage shapes checkpoint staffing and turning movements. With 55% inbound on 42 peak trips, inbound peak equals 23.1 and outbound peak equals 18.9. Align inbound peaks to morning briefings, material call-ups, and shift starts. Where outbound peaks coincide with off-haul loads, confirm that curb radii, flagging, and queue storage accommodate longer vehicles without blocking emergency access.
Reporting and update cadence
Exportable tables support traffic control plans and subcontractor coordination. Distribute CSV to planners for scenario testing and PDF to field supervisors on site. Track actual counts for three days, then adjust peak factor and shares until predicted peaks match observed peaks within 5–10%. Document assumptions, include weather notes, and re-run the calculator whenever site logistics change.
FAQs
What does “trip distribution” mean on a construction site?
It breaks total site trips into vehicle categories and directions so you can plan gates, staging, parking, and haul routes with realistic peak-hour demand.
How do I choose a peak hour factor?
Use observed gate counts when available. Otherwise start at 8–12% for typical weekdays, then increase for pours, major deliveries, or limited access windows.
Why should mode shares total 100%?
Shares represent a complete mix of trips. If they exceed or fall short, totals per mode become biased. Auto-normalize scales shares proportionally to keep outputs consistent.
How is inbound versus outbound calculated?
Inbound trips equal total trips times the inbound percentage. Outbound trips are the remainder. The same split is applied to peak-hour totals for staffing and queuing checks.
When should I update the inputs?
Update when project phase changes, delivery patterns shift, access constraints appear, or counts differ from predictions. Weekly updates are typical, with daily checks during critical operations.
What do CSV and PDF downloads help with?
CSV supports scenario analysis in spreadsheets, while PDF is convenient for field distribution, daily briefings, and attaching a snapshot to traffic management documentation.