Section 5: Rechecks of Speed Zones

Introduction

Since the basic data on which speed zones are established are subject to change when conditions change, established speed zones must not
be considered permanent.

Physical improvements to the roadway, increased roadside development, and heavy increases in traffic volumes justify a recheck of speeds to determine whether or not the 85th percentile speed has changed enough to require a change in the zone speeds.

Frequency of Rechecks

Periodic rechecks of all zones are desirable at intervals of about three to five years in urban areas regardless of roadway improvements, roadside developments, or increases in traffic volumes. Trial runs or rechecks of every third speed check station may be made.

In rural areas, rechecks are desirable at intervals of five to ten years. In many instances, trial runs may be sufficient.

If the speed checks or trial runs indicate a need for revision of the zone, rechecks of speeds should be made at all speed check stations for that particular section and a revised strip map made and submitted.

Procedure

In preparing a revised strip map, the original tracing on file with the Traffic Operations Division may be obtained and used where all data, other than speed check data shown thereon, are current. A strip map containing out-of-date information should be considered obsolete
.

New strip maps should be prepared when physical improvements of the roadway have been made or when changes in roadside development have occurred since the original strip map was prepared even though the speed checks and zone speeds may not change.