Learn Italian: L'incidente è successo sul ponte. - The accident happened on the bridge.

In Italian, the past tense uses essere (to be) as the helping verb for verbs of motion, state of being, or events. Succedere (to happen) describes an event, so it takes essere. That's why we say è successo instead of ha successo.

Does the ending of successo change depending on what happened?

Yes! When you use essere as the helping verb, the past participle (here, successo) must agree in gender and number with the subject. Since l'incidente is a masculine singular noun, the participle ends in -o. If a feminine thing had happened, it would be è successa.

Where does the word sul come from?

Sul is a combined word made by merging the preposition su (on) and the definite article il (the). We use il because the next word, ponte (bridge), is a masculine singular noun starting with a consonant.

How do I know if a noun ending in -e like ponte is masculine or feminine?