On a when-stopped-popup-notification, not on a 2-way road no. Split highways and freeways which have the cardinal direction as part of the segment name make this easy. The only way to really know for 2-way streets is if the poster would include pertinent details either in text or a voice annotation.
How do you tell the direction of traffic jams, accidents, etc. when you see a report bubble on the map? Sometimes the road has a direction (e.g., I-90 E) or an incident may affect both directions (e.g., a construction), but oftentimes traffic jams affect only one direction, not both. So, when you see a traffic jam alert bubble, is there any way to tell which direction?