Semi{0}}iitreyila ezifakwe efrijini zisetyenziselwa ukuthutha iimpahla ezifuna ukufakwa efrijini kunye nokutsha. Kwiminyaka yakutshanje, ngokukhula kokuthandwa kokuhamba ngetsheyini ebandayo, imfuno ye-semi{2}}yetreyila ekhenkcezisiweyo nayo iyakhula, ngenxa yezi zinto zilandelayo:
1. Iimfuno zelizwe lolungiselelo lolungiselelo lomgangatho wemithwalo ziya zisiba ngqongqo, nto leyo eyenza ukuba iilori ezifakwe efrijini zibe yimfuneko ekutyeni okutsha.
2. Ngokuziswa kwemithetho emitsha kazwelonke, ii-semi{1}}ezirhuqwayo zikwazi ngcono ukuphepha ukugcwala kunezinye iilori ezifakwe efrijini.
3. Iitreyila ezifakwe efrijini-zinokufikelela kufutshane{2}}zero yenkunkuma ekuthuthweni kweziqhamo nemifuno, ngeqondo lokonga amafutha elingaphezulu kwe-20% kunye nomahluko wobushushu obuyi-±1 degree, ukunciphisa kakhulu ilahleko yezothutho kunye nokuphucula ukusebenza kakuhle kwezothutho.
4. Isemi{1}}iitreyila ezifakwe efrijini zinde, zifikelela kubude be 13.5 okanye 15 yeemitha. Oku kuvumela imithwalo emikhulu, ukonga amafutha, kwaye kufake isandla ekuphuculeni izibonelelo zezoqoqosho zizonke zothutho lwendlela.
Kuhambo oluphakathi nolude{0}}lohambo olubandayo, iinqwelo ezirhuqwayo ezisefrijini -zisoloko zingamandla aphambili. Phantsi kwemfuno emandla yemalike, kusengenzeka ukwenza imali ngokuqhuba iitreyila -ezifakwe efrijini ukuthutha iimpahla.
