Introduction to CMS

Welcome to Changeable Message Signs

Changeable Message Signs, sometimes called Uniform Manual Traffic Control Devices, are an effective tool to provide real-time traffic regulatory, warning, or guidance information to the traveling public. In most cases, the messages displayed on CMS are related to traffic delays, travel times, lane closures, rerouting due to traffic incidents, and similar strategies to manage traffic actively on the highway system.  With few exceptions, the SOP limits the use of CMS to the display of traffic operational, regulatory, warning, and guidance information. 

Our Changeable Message Signs system is operated through SAR's Computer Aided Dispatch (CAD) system. The link to this CAD can be found here. To access the CMS system, you must have access to the Department of Motor Vehicles page on the CAD - People with access to this page are handed picked by the Public Works Leadership Team and given and unique key to enter into SAR's CAD, to gain access to the DMV page and subsequently the 'Street Signs' page. 

Included in this SOP

The following SOP will use a variety of methods to simplify the required structure of CMS messages, including visual representations of the messages on a matrix board - Below you can see an example of such a diagram. Additionally, through out this SOP the rows on the CMS boards will be referred to as 'ROW A', 'ROW B' and 'ROW C', all of which can also be seen below in their respective positions.

We will also go over messages that are strictly prohibited from being displayed, and how messages should be correctly formatted, including the appropriate abbreviations.