3-2Roundabout Design

Roundabout design follows NCHRP Report 672 and FHWA Roundabouts: An Informational Guide. TxDOT considers roundabouts as the preferred alternative for new intersections where volumes and geometry are suitable. Single-lane roundabouts: inscribed circle diameter 90-180 ft, entry width 14-18 ft, circulating width 15-20 ft. Multi-lane roundabouts require capacity analysis using the HCM methodology and swept path analysis for the design vehicle.

References: AASHTO current edition, TX Standard Specifications, FHWA Technical Advisories, and applicable federal regulations (23 CFR). Contractors shall maintain current copies of all referenced standards on the project site.