Photograph of highway sign from Jinghong (Thai Chiang Rung) in Sibsongbanna / Sipsong Panna / Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, PRC:
We needn't worry overmuch about the first two directions (with the blue background), because they are basically rendered correctly (except for the typo of "Whithe" for "White"); note the use of "t" for dūn 吨 ("ton").
However, the direction with the yellow background needs some unpacking and explanation:
quánchéng jiānkòng zhuāpāi chǔfá 全城监控抓拍处罚
("[closed circuit television] monitoring throughout the city; [violators] will be recorded and ticketed")
There was considerable disagreement among those who offered their interpretation of the Chinese sentence. Most of the problems centered around how to understand zhuāpāi 抓拍. It does mean "take a snapshot", but in this context it would be better to think of it as "capture an image of".
More literally, chǔfá 处罚 means "punish".
As for the lettering that is neither Chinese nor English, Pattira Thaithosaeng writes:
Unfortunately, I cannot find anyone who can read it. However, one of my friends who is a native of Northern Thai told me that it was the new Tai Lue script. The old Tai Lue is very similar to Lanna script (a script used in Lanna Kingdom before it was annexed, and still in use today in the northern part of Thailand). In the new Tai Lue script, the tone marks are put in the same line with the letters.
Perhaps one of our Language Log readers knows how to transliterate and translate the Tai Lue writing or can find someone to do so.
After I had finished writing the above, I received the following from Trent Walker, who kindly transliterated and translated all of the New Tai Lue writing on the sign:
The sign in written in New Tai Lue script, which is used today by the government to write the Tai Lü language (傣仂语) in the PRC. I can read the script, but I am not competent in Tai Lü itself. However, it is similar enough to Lao and Northern Thai that I can hazard a transliteration and translation. I have given these below:
Roman-script transliteration [EFEO system]: lot lāk gho phat pai bāy khvā
Thai-script transliteration: โลด ลาก โฆ ผด
In Central Thai orthography: รถลากคอ ผลัดไปภายขวา
English translation: Pulling-vehicles [i.e. trucks?] turn to the right side
Roman-script transliteration: goṅ pai bāy kho ḷoṅ dhāt pheīk1
Thai-script transliteration: โคง ไป พาย ขอ
In Central Thai orthography: โค้งไป ภายขัวล่วงธาตุเผือก
English translation: Detour to go to the [other?] side [:] White Stupa Bridge
Roman-script transliteration: dāṅ sīn2 nīa mī ho cak ṅàt1 Hop fā2 phai
Thai-script transliteration: ทาง สี้น นีะ
In Central Thai orthography: ทาง เส้นนี้มีหอชักงวดรูปฝ้าใผ OR ทั้งสี้นนี้มีหอชักงวดรูปฝ้
English translation: This road has towers taking timed photographs to penalize anyone OR There are towers everywhere taking timed photographs to penalize anyone
The first two parts of the sign are straightforward and I am confident in my interpretation, with the exception of the word for "truck" in Tai Lü and the exact meaning of "side" [bāy] in this context (presumably 境?).
The third part is more difficult. dāṅ sīn2 nīa mī ho could mean "This road has towers" or "There are towers everywhere." Neither lines up exactly with 全城监控, though the perhaps the second interpretation is preferable.
fā2 phai is also problematic. The word "fā2" in Tai languages can mean foggy, vague, blemish, or scum, which are not the right meanings for this context. I am wondering whether it is loanword from Chinese, namely 罚 (fá) [i.e. if ฝ้า (fā2) = 罚 and ใผ (phai) = ผู้ใด = who] . I think this is the more likely interpretation. Another possible interpretation is that fā2 phai is related to Bai Bā2 (pronounced fai fā2 in Thai and Lao), meaning "electric" [i.e. if ฝ้าไผ = ฟ้าไฟ = ไฟฟ้า = electric], but this strikes me as unlikely.
[h.t. Michael Rank; thanks to Jing Wen, Maiheng Dietrich, Bob Bauer, Fangyi Cheng, Yixue Yang, Susanne Ryuyin Kerekes, and Sara Davis]