Roundabout design follows NCHRP Report 672 and FHWA Roundabouts: An Informational Guide. PennDOT 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.
All work under this section shall comply with PennDOT current standards and applicable AASHTO, ASTM, and federal requirements. The Engineer has authority to accept or reject materials and workmanship that do not conform to the specifications.
Source: PennDOT Highway Design Manual, 2024 Edition. Pages 17–18 of 37.