ITE Journal - August 2020 - 31

cut-through of the splitter island can be provided when bicyclists
will cross at-grade on approaches.

Figure 6. Raised lane divider with demarcating feature.
if they are available. Where bicyclists use bicycle lanes or
shoulders on the approach roadways, they should be terminated
in advance of the circulatory roadway and crosswalks with
enough length remaining for bicyclists to merge into traffic (and
similarly, reintroduced on exit legs downstream of crosswalks).
If bicyclists are required to utilize the sidewalk, sidewalks should
meet shared use path width requirements. A pavement-level

While fatal crashes at roundabouts are much less likely than
traditional three- and four-leg intersections, motorcyclists are
overrepresented in those fatal crashes. The international literature
on turbo roundabouts does not currently include insights on motorcycle-involved crashes at turbo roundabouts. There are several
roadway features that can have a significant impact on motorcycle
safety performance at turbo roundabouts, including the presence
and location of raised lane dividers and curbing, surface friction,
pavements markings, drainage, sight distance, radii, the roadside
environment, and surface conditions. Specific concerns for motorcyclists in turbo roundabouts are the truck apron and lane divider
options that are raised. Sloped curbing with minimal vertical
reveal can provide a more forgiving environment to motorcycles
compared to vertical or rolled curbing. Designers can also provide
supplemental signage alerting motorcyclists to these elements of
turbo roundabouts. Potential alternatives to the raised lane dividers
were identified earlier in this paper.
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ITE Journal - August 2020

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