Provide the appropriate number of lanes and lane assignment to achieve adequate capacity, lane volume balance, and lane continuity to ensure that the roundabout operates at an appropriate level of service;

Design to accommodate the largest anticipated vehicle to enter, circulate and depart efficiently while also providing adequate speed control for passenger vehicles;

The circulating roadway should be wide enough to accommodate the local jurisdiction largest vehicle (fire truck or city bus), with a truck apron provided around the central island for over-tracking of the rear axles on larger vehicles;

A central island that is clearly visible from the approach sight distance at the road operating speed in advance of the roundabout. Landscaping or hardscaping within the central island can be effective in restricting sight distance to the minimum requirements while creating a terminal vista on the approach to improve visibility of the central island;

Drivers must be able to see to the left early enough to safely enter the roundabout. However, excessive intersection sight distance may lead to higher vehicle speeds that reduce the safety of the intersection for all road users (motorists, bicyclists, pedestrians);

Design such that the driving task is as simple as possible, avoiding the use of spiraled lanes unless warranted by traffic (i.e., dedicated left-turns and other reasons cited in , Section 10.7.7); and

Site-specific design to meet the needs of pedestrians and cyclists.