For greater convenience to traffic and more effective
police and fire protection, permanent dead-end streets shall be limited in
length to 900 feet and shall be provided at the closed end with a turnaround
having an outside roadway diameter of at least 80 feet and a street property
line diameter of at least 100 feet. In zoning districts, however, which permit
lots of less than one acre, the minimum outside roadway diameter shall be
increased to 100 feet and the diameter at the property line shall be increased
to 120 feet. Where it is impossible to subdivide a property except by a dead-end
road which is longer than 900 feet, the Board may permit a greater length,
provided that a divided roadway with center mall is constructed in a seventy-foot
right-of-way (or greater width, if required) in such a manner that either
side of the roadway could be used, in emergencies, for two-way traffic.