Bumper ifite umurimo wo kurinda umutekano, gushushanya no kunoza ikirere kiranga ikinyabiziga. Duhereye ku mutekano, imodoka irashobora kugira uruhare runini mugihe habaye impanuka yo kugongana byihuse, kugirango irinde umubiri wimodoka imbere ninyuma; Mugihe habaye impanuka nabanyamaguru barashobora kugira uruhare runini mukurinda abanyamaguru. Uhereye kubigaragara, birashushanya kandi bihinduka igice cyingenzi cyimiterere yimodoka. Mugihe kimwe, bumpers zimodoka nazo zigira ingaruka runaka yindege.
Muri icyo gihe, mu rwego rwo kugabanya ibyangiritse ku bayirimo mu gihe habaye impanuka ziterwa n’impanuka, ubusanzwe imodoka ziba zifite ibyuma byo kumuryango kugirango zongere imbaraga zo kurwanya impanuka. Ubu buryo ni ngirakamaro, bworoshye, impinduka nke kumiterere yumubiri, yakoreshejwe cyane. Nko mu 1993 imurikagurisha mpuzamahanga ry’imodoka rya Shenzhen, hafunguwe umuryango wimodoka kugirango berekane bumper kugirango abayireba babone, kugirango berekane imikorere myiza yumutekano.
Kwishyiriraho urugi rwumuryango biri muri buri rugi rwicyapa cyumuryango utambitse cyangwa uhagaritse ibyuma byinshi byimbaraga zikomeye, bigira uruhare runini rwimodoka imbere yimodoka inyuma, kuburyo imodoka yose ikikije bamperi "kurinda", ikora "urukuta rwicyuma", kuburyo uwatwaye imodoka afite ahantu hafite umutekano muke. Birumvikana ko kwishyiriraho inzugi zumuryango byanze bikunze bizamura ibiciro kubakora imodoka, ariko kubatwaye imodoka, umutekano numutekano biziyongera cyane.
