Question 1

What is the maximum road slope for vehicles?

Accepted Answer

Highway standards typically limit grades to 6-8% for freeways and 10-12% for local roads. Parking ramps can go up to 15-20%. Above 15%, traction becomes problematic in wet or icy conditions. ADA accessibility requires maximum 1:12 (8.33%) for ramps.

Question 2

What slope is needed for drainage?

Accepted Answer

Minimum drainage slopes: 1% (1:100) for paved surfaces, 2% for unpaved, 1% for gutters, and 1-2% for underground pipes (varies by diameter — larger pipes need less slope). Flat roofs require minimum 1.5-2% slope to prevent ponding.