I would like to post in my students play yard, "Only go down the slides, they were not designed to be run/ran up and if this action continues they will break".
This is one of those cases that confuses a lot of people, because it doesn't follow the usual rules.
To make a passive voice infinitive (which is what you're doing here), you combine "to be" with the past participle of the verb you want. For most verbs, this is relatively straightforward, because the past participle is the same as the simple past tense of the verb (for example, "to use" -> "to be used", "to make" -> "to be made", etc). Because of this, most people just get used to thinking of it as "to be" + past tense of the verb, which is true for the majority of cases.
But "to run" is an irregular verb, and in the case of this verb one of the irregularities is that its past participle is actually not the same as its past tense form, so while the past tense of "run" is "ran", the past participle of "run" is actually still "run".
So the proper passive form of "to run" is:
to be run