ASTM D4956 Sheeting Types Explained

If you supply traffic signage, ASTM D4956 is the specification your customer’s engineer is working from. It classifies retroreflective sheeting into Types by construction and brightness, and every state DOT specification and approved-products list references it. Getting a Type wrong on a quote means either losing the bid or supplying material the agency cannot accept.

First: two Types no longer exist

Types VII and X have been discontinued. Their products were reassigned to Type VIII. FHWA’s Traffic Sign Retroreflective Sheeting Identification Guide documents the change by comparing the D4956-04 and D4956-13 revisions — under -04 the microprismatic group was “VII, VIII, X,” and under -13 it is simply “VIII.” FHWA’s own retroreflectivity table, which cites D4956-09, already omits VII and X.

We previously dated this change to the D4956-11a revision. We have removed that attribution: FHWA’s guide names only the -04 and -13 revisions and does not date the reassignment to a specific one, and we have not seen the ASTM revision record itself. What is certain is that the reassignment happened between -04 and -13.

The current Types are I, II, III, IV, V, VI, VIII, IX and XI — nine of them, with gaps where VII and X used to be. Any supplier page or spec sheet still listing Type VII or Type X is out of date, and citing them on a submittal invites a rejection.

The Type table

A note on precision: D4956 describes Types VIII, IX and XI all as unmetallised microprismatic. The commonly used phrase “cube corner” is industry shorthand rather than the standard’s wording, and it does not by itself distinguish the three.

Type	Common name	Construction	Typical use
I	Engineer grade	Enclosed lens glass bead, or microprismatic	Permanent highway signing, construction zones, delineators
II	Super engineer grade	Enclosed lens glass bead, or microprismatic	As Type I
III	High intensity	Encapsulated glass bead, or microprismatic	As Type I
IV	High intensity prismatic	Unmetallised microprismatic	Permanent signing, construction zones, delineators
V	Super high intensity	Metallised microprismatic	Typically delineators
VI	Elastomeric / roll-up	Elastomeric high-intensity sheeting without adhesive, typically vinyl microprismatic	Orange temporary roll-up warning signs, cone collars, post bands
VIII	Very high intensity prismatic	Unmetallised microprismatic	Permanent highway signing, delineators
IX	Very high intensity prismatic, wide observation angle	Unmetallised microprismatic	Permanent signing, delineators
XI	Highest performance prismatic	Unmetallised microprismatic	Permanent signing, delineators

For which ORALITE grade satisfies each Type, see the ORALITE to ASTM D4956 crosswalk.

Minimum retroreflectivity for new sheeting

Values are the minimum coefficient of retroreflection (R_A) at 0.2° observation angle and −4° entrance angle, in candelas per lux per square metre. This is the table FHWA publishes for rigid signs.

Type	White	Yellow	Fluorescent yellow	Green	Red
I	70	50	—	9	14
II	140	100	—	30	30
III	250	170	—	45	45
IV	360	270	220	50	65
VIII	700	525	420	70	105
IX	380	285	230	38	76
XI	580	435	350	58	87

Two observations worth making, because they surprise people.

Type IX is dimmer than Type VIII on paper. 380 against 700 on white. Type IX is not a downgrade — it is optimised for large observation angles. Observation angle is the angular separation between the headlamps and the driver’s eyes as seen from the sign, and it grows as the vehicle gets closer, so Type IX performs better in exactly the close-range situation this single-geometry table does not capture. Note that this is a different quantity from entrance angle, which the table fixes at −4°. It is why Virginia specifies Type IX for illuminated overhead signs and Type XI for unlit ones.

Type XI is not simply “the brightest.” At 580 white it sits between IX and VIII on this geometry. It is the highest-performance sheeting across the range of angles a driver actually encounters, which is a different claim.

A caution on these numbers

ASTM D4956 is paywalled, and the current active revision is D4956-26. The values above are FHWA’s published table, which cites D4956-09, cross-checked against the D4956-04 and D4956-19 texts — Types I through IV, VIII and IX are identical across all three, which is good evidence the values are stable. They have not been checked against the -26 revision. Before putting a retroreflectivity minimum into a contract submittal, verify against the current standard.

Values not publicly available anywhere we could verify: Type XI orange and blue, Types V and VI under the -19 and -26 revisions, and fluorescent orange for any Type. If you need those, the standard itself is the only source.

The related standard your customer may cite instead

AASHTO M 268 is the parallel specification and it uses letter designations — Type A, B, D and so on — rather than Roman numerals. Some states specify by M 268 letter instead of D4956 numeral; Tennessee, for instance, specifies AASHTO M 268 Type D for larger extruded and overhead signs. If a spec arrives with letters instead of numerals, that is why. The letter-to-numeral mapping lives inside M 268, which is also paywalled.

What this does not tell you

D4956 classifies the material. It does not tell you which Type a given sign requires — that is set by the specifying agency, and states genuinely disagree with each other. See which ASTM sheeting type does your state require, and for the maintained-brightness obligation that sits alongside it, MUTCD retroreflectivity requirements.