2 Del. Admin. Code § 2L.05

Current through Register Vol. 28, No. 5, November 1, 2024

Section 2L.05 - Message Length and Units of Information

Guidance:

01 The maximum length of a message should be dictated by the number of units of information contained in the message, in addition to the size of the CMS. A unit of information, which is a single answer to a single question that a driver can use to make a decision, should not be more than four words.

Support:

02 In order to illustrate the concept of units of information, Table 2L-1 shows an example message that is comprised of four units of information.

03 The maximum allowable number of units of information in a CMS message is based on the principles described in this Section, the current highway operating speed, the legibility characteristics of the CMS, and the lighting conditions.

Standard:

04 Each message shall consist of no more than two phases. A phase shall consist of no more than three lines of text. Each phase shall be understood by itself regardless of the sequence in which it is read. Messages shall be centered within each line of legend. Except for signs located on toll plaza structures or other facilities with a similar booth-lane arrangement, if more than one CMS is visible to road users, then only one sign shall display a sequential message at any given time.

05 Techniques of message display such as fading, rapid flashing, exploding, dissolving, or moving messages shall not be used. The text of the message shall not scroll or travel horizontally or vertically across the face of the sign.

Guidance:

06 When designing and displaying messages on changeable message signs, the following principles relative to message design should be used:

A. The minimum time that an individual phase is displayed should be based on 1 second per word or 2 seconds per unit of information, whichever produces a lesser value. The display time for a phase should never be less than 2 seconds.

B. The maximum cycle time of a two-phase message should be 8 seconds.

C. The duration between the display of two phases should not exceed 0.3 seconds.

D. No more than three units of information should be displayed on a phase of a message.

E. No more than four units of information should be in a message when the traffic operating speeds are 35 mph or more.

F. No more than five units of information should be in a message when the traffic operating speeds are less than 35 mph.

G. Only one unit of information should appear on each line of the CMS.

H. Compatible units of information should be displayed on the same message phase.

Table 2L-1. Example of Units of Information

Question	Answer	Number of Information Units
What happened?	MAJOR CRASH	1
Where?	AT EXIT 12	1
Who is the advisory for?	Drivers Heading TO NEW YORK	1
What is advised?	USE ROUTE 46	1

Note: The following is an example of a two-phase message that could be developed from the four information units shown in this table:

	MAJOR CRASHAT EXIT 12			USE ROUTE 46TO NEW YORK
	Phase 1			Phase 2

Option:

07 A unit of information consisting of more than one word may be displayed on more than one line. An additional changeable message sign at a downstream location may be used for the purpose of allowing the entire message to be read twice.

Guidance:

08 If more than two phases would be needed to display the necessary information, additional changeable message signs should be used to display this information as a series of two distinct, independent messages with a maximum of two phases at each location, in accordance with the provisions of Paragraph 4.

09 When the message on a CMS includes an abbreviation, the provisions of Section 1A.15 should be used.

2 Del. Admin. Code § 2L.05