Planning, Trip Distribution & Crash Rates

1. Trip generation: how many trips each zone produces and attracts.
2. Trip distribution: where they go, usually by a gravity model.
3. Mode choice: which mode, usually by a logit model.
4. Traffic assignment: which route.

Worked

• Zone 1 produces 1,000 trips. Zone 2 attracts 400 with F = 2; zone 3 attracts 600 with F = 1. AF products are 800 and 600, so T₁₂ = 1,000 × 800/1,400 = 571 and T₁₃ = 429. The nearer zone wins despite attracting fewer trips.
• An intersection had 12 crashes in 3 years with 18,000 vehicles entering a day: R = 12 × 10⁶/(365 × 3 × 18,000) = 0.61 crashes per million entering vehicles.