Public agencies have to keep their signs above a floor of measured brightness, and they have to be using a documented method to do it. This page covers what the current MUTCD actually requires, where the numbers live, and the citation errors that show up constantly in supplier literature.
Which edition is in force
The 11th Edition of the MUTCD, dated December 2023. The final rule published 19 December 2023 and took effect 18 January 2024. It is adopted as the national standard by 23 CFR 655.603(a), which makes it binding on “all traffic control devices installed on any street, highway, or bicycle trail open to public travel.”
23 CFR 655.603(b)(3) requires states to adopt FHWA’s changes “within two years from the effective date of the final rule.”
The first citation error: it is Table 2A-5 now
In the 2009 MUTCD, minimum maintained retroreflectivity lived in Table 2A-3, under Section 2A.08. In the 11th Edition it is Table 2A-5, under Section 2A.22, with the retroreflection requirement itself in Section 2A.21.
FHWA’s own brochure FHWA-SA-07-020 is still posted and still uses the old numbering, which is how the wrong citation keeps propagating. If you see “MUTCD Table 2A-3” cited for retroreflectivity, that page is working from the 2009 edition.
What Section 2A.21 requires
The core requirement, in full — and the closing clause matters, because it is the exception that lets particular signs escape:
“Regulatory, warning, and guide signs (see Section 2A.03), and object markers, shall be retroreflective or illuminated to show the same shape and similar color by both day and night, unless otherwise provided in this Manual for a particular sign or group of signs.”
Two further provisions matter commercially:
“Where the color black is specified for the legend or background of a sign, an opaque and non-retroreflective material shall be used.”
“The requirements for sign illumination shall not be considered to be satisfied by street or highway lighting.”
That last one closes a loophole agencies used to lean on. A well-lit street does not exempt the signs on it.
What Section 2A.22 requires
Agencies “shall use an assessment or management method that is designed to maintain sign retroreflectivity at or above the minimum levels in Table 2A-5.”
Read that carefully, because it is more forgiving than it first appears. Compliance is achieved when a method is being used — an agency is not in violation because an individual sign has temporarily dropped below the minimum. The obligation is to run a programme, not to guarantee every sign at every moment.
Agencies may exclude four categories: parking, standing and stopping signs; walking and hitchhiking signs; acknowledgment signs; and signs on exclusive bikeways.
The minimum levels
Values are in candelas per lux per square metre, measured at 0.2° observation angle and −4.0° entrance angle. The table is indexed by colour combination, by whether the sheeting is beaded or prismatic, and by mounting position.
| Sign colour | Beaded Type I | Beaded Type II | Beaded Type III | Prismatic Sheeting | Applies to |
|---|---|---|---|---|---|
| White on green | W* · G ≥ 7 | W* · G ≥ 15 | W* · G ≥ 25 | W ≥ 250 · G ≥ 25 | Overhead |
| White on green | W* · G ≥ 7 | W ≥ 120 · G ≥ 15 | — | — | Post-mounted |
| White on blue | W* · B ≥ 3 | W* · B ≥ 5 | W* · B ≥ 12 | W ≥ 250 · B ≥ 12 | Overhead |
| White on blue | W* · B ≥ 3 | W ≥ 120 · B ≥ 7 | — | — | Post-mounted |
| White on brown | W* · Br ≥ 1 | W* · Br ≥ 5 | W* · Br ≥ 10 | W ≥ 350 · Br ≥ 10 | Overhead |
| White on brown | W* · Br ≥ 1 | W ≥ 150 · Br ≥ 5 | — | — | Post-mounted |
* An asterisk in Table 2A-5 means that sheeting type shall not be used for that colour in that application. It is a prohibition, not a recommendation — note that FHWA’s 2012 memorandum prints the same footnote as “should not,” but the MUTCD text governs.
A note on that prismatic column. In the 11th Edition the heading reads simply “Prismatic Sheeting” and names no ASTM Types. The 2009 edition’s Table 2A-3 did name them in the heading (III, IV, VI, VII, VIII, IX, X), and FHWA’s 2012 memorandum prints a Type list too — which is why you will see Type numbers attached to this column in secondary sources, including on this site previously. The current table does not carry them.
Table 2A-5 also carries rows for black on yellow or orange, white on red, and black on white, with additional criteria keyed to sign size and symbol weight, and a minimum 3:1 contrast ratio requirement for white on red. Read those rows directly from Part 2A of the 11th Edition before quoting them — the column placement in the published PDF does not extract reliably, and we are not going to reproduce numbers we cannot confirm cell by cell.
Type XI has no beaded column. FHWA’s guidance is that agencies may apply the levels designated for all prismatic sheetings to Type XI prismatics. For what those Types mean, see ASTM D4956 sheeting types explained.
One thing the table does not contain
There is no row, and no note, for fluorescent yellow-green, fluorescent yellow, or fluorescent orange. Those colours are widely used on school, pedestrian and work-zone signs, and no maintained minimum is published for them in Table 2A-5. A supplier page quoting a maintained minimum for fluorescent yellow-green school signage has invented the number.
The second citation error: the compliance date
Two FHWA sources give two different dates for the same requirement. The FHWA sign retroreflectivity FAQ says 13 June 2014. FHWA’s brochure FHWA-SA-07-020 (revised 2013) says agencies have until 14 June 2014. Both are FHWA, and we have not found a way to resolve it.
If you have to state a date, write “mid-June 2014” or cite both. The requirement itself is unambiguous: by then, agencies had to have an assessment or management method in place and in continued use for regulatory and warning signs.
Guide signs and street name signs have no compliance date. FHWA’s position is that they “are to be added to an agency’s management or assessment method as resources allow.” The 2009 MUTCD’s original January 2015 and January 2018 sign-replacement deadlines were removed by the 2012 revision.
A date not to confuse with this one
Pavement marking retroreflectivity carries a compliance date of 6 September 2026. Be careful where you cite it from: Section 3A.05 sets the maintained levels — 50 mcd/m²/lx at 35 mph or greater, 100 mcd/m²/lx at 70 mph or greater, at the 88.76°/1.05° geometry — but it does not contain the compliance date. The date sits in the MUTCD’s compliance-dates table (Table 1B-1) and derives from FHWA’s final rule of 5 August 2022 (87 FR 47921), effective 6 September 2022. And it is markings, not signs, which is how it gets mixed into sign conversations.
What the MUTCD does not do
It sets performance floors by colour, construction class and mounting. It names no ASTM Type as required for any sign class. Table 2A-4, which lists means of retroreflection, describes them generically — “material with smooth sealed outer surface over microstructure” — without reference to D4956. Which Type you must supply is a state-level decision, covered in which ASTM sheeting type does your state require.
Related technical reading
- ASTM D4956 sheeting types explained
- Which ASTM sheeting type does your state require?
- ORALITE to ASTM D4956 Type crosswalk
- Buy America and BABA for sign sheeting
Sources: MUTCD 11th Edition (December 2023), Part 2A, Sections 2A.21 and 2A.22 and Tables 2A-4 and 2A-5; Part 3, Section 3A.05. Adoption authority: 23 CFR 655.603. Final rule: Federal Register, 19 December 2023, doc. 2023-27178 (RIN 2125-AF85). Pavement marking compliance date per FHWA final rule 87 FR 47921, 5 August 2022. Blue and brown levels cross-checked against FHWA’s memorandum of 5 April 2012. Compliance-date discrepancy between FHWA’s FAQ and FHWA-SA-07-020 noted as found.
