A Pedestrian Scramble is one of many common terms for a dialog crosswalk found in the no-man’s region. This type of lane is easily modeled in the DSRC MAP feature set. A rich discussion of the history of this type of crosswalk can be found in this Wikipedia article.
Common layout styles
The intersection markings used with a Pedestrian Scrambles can vary considerably with local practices. Here are three common examples. From a MAP perspective, it is most important to capture the defined polygon region.
(TODO: final trim of these images)
These examples were taken from
- JacksonBlvd-StateSt, Chicago,
- WestJefferson-McClintock, near USC in Los Angeles, and
- Westwood-LeConte, near UCLA in Los Angeles.
Lane Numbering and Approach Numbering
As a rule it is best to model these types of lane objects either in their own approach number, or to gather them with the other crosswalks. The rules for the SignalGroupId assignment are the same. Read this article for additional numbering details.
Often a Scramble uses a wider lane width than other crosswalks. The MAP developer can easily accommodate various width attributes as described in other use cases such as this one.
Attributes for a Scramble follow the same rules as for other crosswalk.
Note that in the examples above, the crosswalk paths in the intersection near the campus of USC is intersected by a (believed to be at grade) median. If this median was modeled, and if the resulting polygon overlaid with the crosswalk polygon, there might be a need to assert a node point to indicate an path obstruction from an ADA perspective.
Temporary Use during events
In some areas there is a common practice of establishing a Pedestrian Scramble for short term use, such as during or after a special event (read: football game, read: Michigan). This type of temporary lane object is handled in the same fashion as other temporary lanes.
In other words, the lane is described in the static map message in the normal way, and invoked into an active state by the SPaT message when required. This article (<– to be written still) describes this process in more detail.
See Also: This articles on unusual crosswalk shapes/paths, and on doglegs (<– link tbd) with crosswalk paths.