¥Institute Of Transportation Engineers;
(urban highways)
¥ ITE Committee 4M-25, Speed Zone
Guidelines:
¥ÒThus, the overriding
basis (from a safety perspective) for speed zoning should be that the creation of the zone, and the speed limit
posted, results in an increase in the percentage of
motorists driving at or near the 85th percentile speed.Ó
¥ ÒA third rationale is the need for consistency between the
speed limit and other traffic control devices. Signal
timing and sight distance requirements, for example, are based on the prevailing speed. If these
values are based on a speed limit that does not reflect the
prevailing speed of traffic, safety may be compromised.Ó
¥ Ò2. The speed limit within a speed zone shall be set at the
nearest 5 mph increment to the 85th percentile of free
flowing traffic or the upper limit of the pace of the 10
mph pace.Ó ÒIn no case should the
speed limit be set below the 67th percentile speed of free
flowing traffic.Ó