1. Kev sib cais muaj nuj nqi: Cov kev txwv tsis pub tsav tsheb cais lub cev muaj zog, tsis muaj tsheb, thiab cov neeg taug kev, vertically sib cais ntawm txoj kev, tso cai rau cov tsheb, cov tsheb tsis muaj tsheb, thiab cov neeg taug kev sib cais, txhim kho txoj kev nyab xeeb thiab kev tsav tsheb.
2. Kev thaiv kev ua haujlwm: Cov kev thaiv tsheb yuav thaiv kev coj tus cwj pwm tsis zoo thiab tiv thaiv cov neeg taug kev, tsheb kauj vab, lossis tsheb tsav sim hla txoj kev. Nws yuav tsum tau guardrails kom muaj ib tug tej qhov siab, ceev (xa mus rau ntsug barriers), thiab lub zog.
3. Kev ceeb toom muaj nuj nqi: Los ntawm kev txhim kho nws, cov txheej txheem ntawm lub guardrail yuav tsum ua kom nruj thiab meej, ceeb toom cov neeg tsav tsheb kom xyuam xim rau lub neej ntawm cov neeg saib xyuas thiab cov neeg taug kev thiab cov tsheb tsis muaj tsheb, txhawm rau tiv thaiv kev sib tsoo.
4. Kev ua kom zoo nkauj: Los ntawm kev siv cov khoom sib txawv, cov ntaub ntawv, cov duab, thiab xim ntawm cov guardrails, nws ua tiav kev sib haum xeeb thiab kev sib koom tes nrog txoj kev ib puag ncig.