(1)    Principle of consistency
The principle of consistency makes the public signs effective in social function. The public signs are used to provide the information and meet the needs of the public. If the translations are not unified, readers may receive wrong information. Principle of consistency refers to the unity in international standard. The most useful and easiest way is to directly use the English equivalents in western countries. The familiar notice in public place “游客止步” has various versions of translation, such as “Stop”, “Guest Go No Further” and “No Visitors”. These translations are not true English expression, and then they cannot fully display the instructive function of public signs. In English-speaking countries, the general expression of “游客止步” is Staff Only. The principle of consistency also refers to the unity in fixed and traditional translation. Some names of places have a long history and are accepted by many people, such as “Pingan Theater”.
(2)    Principle of conciseness
Since the public signs are put up in the public places to convey the information at people’s first sight, translation should be concise and clear. This paper comes up with the principle of conciseness, which includes two meanings. The first one is that the translation should be short and brief without unnecessary words; the second one is using simple vocabulary and sentence patterns. Owing to the limited time and space, clear and concise translations are essential. Taking the Chinese public sign “绕行三五步，留得芳草绿”、“茵茵绿草地，脚下请留情”、“小草给我一片绿，我给小草一份爱” for example. If you translate them into “green and beautiful grass, please mind your foot”, the translation is too long and confusing. Just translate them into “keep off the grass”.
(3)    Principle of comprehensibility
The principle of comprehensibility refers to the readability of translation. It requires that C-E translations should be easy to understand for westerners and avoid Chinglish. The purpose of public signs translation is to help foreigners with their life, study, work and travel in China. When translating the public signs, translators have to prioritize the readers, taking their culture and receptivity into consideration.
3.2 Translation methods
Interlingual transfer is important in translation. The process of translation is limited by behavior model and thought model. Having a deep knowledge about Chinese and English is helpful for improving efficiency and quality of interlingual transfer. Therefore, the study of translation methods should pay attention to interlingual transfer, and use different but appropriate methods.
3.2.1 Literal translation
Literal translation, also known as direct translation or word-for-word translation, is the rendering of text with or without conveying the sense of the original. It’s a type of translation in which more attention is given to preserving the wording intact.
This method usually is used in some nominal public signs. The nominal public sign, namely is the information telling people what it is. Usually they are tapped on the wall or doors, such as “Entrance（入口）”, “Exit（出口）”, “Help Button（求助按钮）”, “Information（咨询处）”, “Taxi Pick-up Point（出租乘车站点）”and “Business Center（商务中心）”.
Literal translation is a basic translation method. But it cannot be used in any situation because some literal translations cannot convey original meaning or even produce ambiguity.
3.2.2 Free translation
Free translation is used to convey the meaning and spirit of the original without trying to copy its sentence pattern. It’s also known as sense-for-sense translation, which emphasizes the transfer of the meaning over the accurate reproduction of original wording. 城市公示语英译现状及对策研究英文论文(4):http://www.youerw.com/yingyu/lunwen_452.html