City of Frisco Engineering Standards

Engineering Standards
the approach stopping sight distance to the crosswalk or the yield line, the stopping sight
distance to the crosswalk on the next exit, and the intersection sight distance to circulating
vehicles and vehicles entering at the immediate upstream entry. For circulating vehicles, this
includes the stopping sight distance on the circulatory roadway.
13. Parking is prohibited within a roundabout.
14. On any approach to a roundabout, driveways, alley connections, and on-street parking shall
not be permitted between the crosswalk and the yield line nor along any portion of street that
contains a splitter island.
15. The ROW for a roundabout shall extend a minimum of twelve feet (12’) beyond the back of
its outer curb. The ROW for any street entering the roundabout will flare out as the street
flares so that a minimum of twelve feet (12’) is provided beyond the back of curb on each
side of the street.
16. The roundabout entries and exits and the pavement contained within the inscribed circle
radius shall be constructed on a uniform plane of the same grade, which shall not exceed two
percent (2%). Roadway approaches to the roundabout shall have a maximum slope of two
percent (2%) for a distance of at least two hundred feet (200’) for Type B thoroughfares and
at least one hundred feet (100’) for Type C, D, E, F, and G thoroughfares.
17. Roundabouts shall be illuminated by street lights as described in FHWA’s Roundabouts: An
Informational Guide.
Exit width
Entry width
Circulatory
Roadway
Width
Inscribed
Circle
Radius
Truck Apron
(if necessary)
Yield Line
Pavers
Central island radius
Mountable curb
Splitter island
(mountable curb)
FIGURE 2.6: Typical Roundabout
Section 2 – Thoroughfare Design Requirements May 2012 Page 2-15