Traffic forecasting: If the present Average Daily Traffic (ADT) is 5000 vehicles and the annual growth rate is 10%, what is the average daily flow after 5 years (geometric growth)?

Introduction / Context:Traffic forecasting is essential for capacity analysis and pavement design. When growth is compounded annually, future ADT is obtained using geometric progression. This quick computation feeds into design year volumes and equivalent axle load calculations.

Given Data / Assumptions:

• Current ADT (A₀) = 5000 vehicles/day.
• Annual growth rate g = 10% = 0.10.
• Time horizon n = 5 years.
• Use geometric growth (compounded annually).

Concept / Approach:

The geometric growth formula for average daily traffic after n years is Aₙ = A₀ * (1 + g)^n. Substitute the given values and compute to the nearest 10 vehicles (as in the options).

Step-by-Step Solution:

Verification / Alternative check:

Check successive compounding: Year 1: 5500; Year 2: 6050; Year 3: 6655; Year 4: 7321; Year 5: ≈ 8053. The result is consistent.

Why Other Options Are Wrong:

• 6050, 7050, 9050: correspond roughly to years 2, between years 2–4, and above year 5 for 10% growth; they are not the 5-year value.

Common Pitfalls:

• Applying linear growth instead of compound growth, which underestimates future volumes.
• Rounding too early and getting 8000 instead of ≈8050.

Final Answer:

8050 vehicles.