Streets designed to have one end permanently closed or in the form of a cul-de-sac shall be no longer than six hundred feet and shall be provided at the closed end with a turnaround having a minimum roadway radius of not less than forty feet or with a “Y” or “T” permitting comparable ease of turning. Where deemed necessary, a fire lane of a minimum of twenty feet in width may be required. Temporary dead end streets shall provide a temporary cul-de-sac with appropriate easement for continuation. Provided that streets no more than one lot in depth and intended as required access through a plat having a depth of no more than one lot shall have a street constructed and terminated with barriers approved by the Public Works Director.