Street Design Skill

This skill provides comprehensive street design guidance based on NACTO Urban Street Design Guide, Global Designing Cities Initiative (GDCI), AASHTO Green Book, and international best practices. It covers the full workflow from street hierarchy classification through cross-section dimensioning, intersection design, streetscape specification, and traffic calming.

1. Street Hierarchy Classification

Use the following decision tree to classify any street. Start with the Average Daily Traffic (ADT) count, then apply contextual modifiers.

Primary Classification by ADT and Function

Arterial (>15,000 ADT)

• Right-of-Way (ROW): 30-40m
• Lanes: 2-3 per direction (3.0-3.3m each)
• Design speed: 40-50 km/h (urban), 50-60 km/h (suburban)
• Transit: dedicated bus/BRT lanes strongly recommended
• Cycling: protected bike lanes required (physically separated)
• Pedestrian: wide sidewalks 3.6-6.0m, pedestrian refuge islands at crossings