Radius of bubble in subd.

Architectural Graphic Standards has cul-de-sacs as 35' (small) and 50' (large), so 60 feet would probably be fine if it doesn't have to meet any jurisdictional regulatory requirements. Your probably on the high side but a post a couple of days ago said their jurisdiction required 80'.

We may be mixing radius and diameter in these discussions. Also, whether the property/easement line or the curb.

That [msg=316182]older thread[/msg] began:
"they are now requiring 120' diameter cul-de-sac roadway widths when their subdivision ordinance states and 80' minimum"

See page 65:
http://www.engineering.saccounty.net/Documents/Sect4StreetStds_Saccounty_%20Ver11_01_09.pdf

Whatever oue City Engineering Standards specify. They are based on fire engine turn radii.

I cannot tell which dimension you are wanting to know. You mentioned a 90° turn, where as others are talking about cul-de-sacks.

I have never heard of a "bubble radius".

AASHTO standards usually apply.

I'd get a set of applicable standards, for your area, and follow that.

N