AASHTO SCOTE Annual Meeting – June 14-17, 2009

NCUTCD Summer Meeting – June 18-20, 2009

Manchester, New Hampshire

Section 2E.21 of the MUTCD indicates:Changeable message signs should be capital letters and

have a desirable letter size of 450 mm (18 in) or a minimum letter size of 265 mm (10.6 in).

Section 7.2 of the Changeable Message Sign Operation and Messaging Handbook, August 2004 (FHWA-OP-03-070) indicates:Character heights on CMSs used on freeways and other

high-speed highways should not be less than 18 inchesNational Electrical Manufacturers Association

(NEMA) TS4-2005 standard defines character height as:“the vertical pitch times the number of pixels in the

column of pixels”, or 7 x (Vertical Pitch)

18”

HC = Character HeightP = Pitch (distance between LED’s)ØLED = LED Pixel Diameter

18” Character ExampleØLED = 1.25”P = 2.57”

HC = 7 X 2.57” = 18” orHC = 6 X 2.57” + 1.25” = 16.7”

18”

16.7”

P=2.75”

ØLED=1.5”

P=2.57”

Pixel“Bloom”

Character Height using Physical Measurement

HC = 6 X P + ØLED

Character Height usingNEMA TS4 Definition

HC = 7 X P

18” Character ExampleØLED = 1.5”P = 2.75”

HC = 6 X 2.75” + 1.5” = 18”

ØLED=1.25”

Vendor Using NEMA TS4 DefinitionSign Height = 93”

Vendor Using “Physical” MeasurementSign Height = 101”

Florida Department of Transportation submitted NEMA TS-4 request for interpretation on November 10, 2008

NEMA Technical DMS Committee responded on March 11, 2009:“The NEMA DMS Technical Committee does

not see this request for interpretation as a reason to revise the TS_4 standard, but instead recommends that the standard be followed as written and that agencies require their vendors to provide all the necessary documentation and test results to prove their conformance to the standard. “

Section 4J.03 of the MUTCD indicates:Nominal minimum height and width of each

DOWNWARD GREEN ARROW, YELLOW X, and RED X signal face shall be 450 mm (18 in) for typical applications.

The WHITE TWO-WAY LEFT-TURN ARROW and WHITE ONE WAY LEFT-TURN ARROW signal faces shall have a nominal minimum height and width of 750 mm (30 in).

The color of lane-use control signal indications shall be clearly visible for 700 m (2,300 ft) at all times under normal atmospheric conditions, unless otherwise physically obstructed.

How is the lane-use control signal face measured?

Vendor with 18” High Symbol

Vendor with 13” High Symbol

Vendor with 17” High Symbol

Vendor with 18” High Symbol

Vendor with 13” High Symbol

Vendor with 17” High Symbol

Section 4J.02 of the MUTCD indicates:The meanings of lane-use control signal indications

are as follows: …….E. A steady RED X signal indication shall mean that a road user is not permitted to use the lane over which the signal indication is located and that this signal indication shall modify accordingly the meaning of all other traffic controls present.

Section 4J.04 of the MUTCD indicates:A moving condition in one direction shall be

terminated either by the immediate display of a RED X signal indication or by a YELLOW X signal indication followed by a RED X signal indication.

Is a Flashing Red X operation allowed if no Yellow X indication exists?

Answers?