R78 - woven-planet/opensafety-mbse GitHub Wiki

R78 / 1c:M-1

Walk Signal Span gates pedestrian movement in one or many Crosswalk

Crosswalk pedestrian movement is gated by zero or one Walk Signal Span

---

It stands to reason that a walk/don’t walk signal signals must signal access to at least one Crosswalk. In the case of a Crosswalk extending from one Road Edge to the other without any intervening Crosswalk Access, there is simply one signal and one Crosswalk. Thus the span consists of a single Crosswalk.

If there is a large median splitting two Crosswalks, the same signal typically applies to both. Thus we have a span consisting of two Crosswalks. And in some cases, there will be a separate signal for each connecting Crosswalk. There is nothing to prevent more than two Crosswalks from being managed by the same Walk Signal Span.

Not all Crosswalks are signaled. So a Crosswalk might not be associated with any Walk Signal Span.

Formalization

Signal Controlled Crosswalk.Crosswalk -> Crosswalk.ID
Signal Controlled Crosswalk.Walk signal span -> Walk Signal Span.ID