Roadway system planning takes the big picture view-community, region, or even statewide. It looks at the network as the sum of its parts and understands the relationship between those parts and the capability, impacts, and effectiveness of the system as a whole. Roadway systems planning fits well with comprehensive land use planning and is more appropriate at the level of the community as a whole than at the neighborhood level. The intended audience for this report includes transportation professionals who are developing comprehensive and subarea plans including new or modified transportation systems. The proposed recommended practice expands on previous reports by including a more thorough examination of layered roadway networks encompassing several travel modes and also addresses several emerging special issues in roadway system planning important to the successful implementation of multimodal roadway networks. into traffic,~(4,5) have smaller useful fields of view,~7 do not scan the entire roadway efficiently (or at all),~(6,9) and are slower to respond to critical events.~8 Additionally, these distraction related effects may be exacerbated by fatigue,~1 individual difference characteristics (e.g., age~(1,5,11)), or use/ abuse of substances. We want to be clear that we are not disputing the notion that eyes-off-road distractions are an extremely dangerous problem and certainly are a major contributor to the cause of crashes and incidents. Rather, we are suggesting that eyes-off-road distractions cover only a portion of distraction-related driving impairments and that simply keeping a driver's eyes on the road is not sufficient to eliminate crashes and incidents. When evaluating distracted driving, it is important to understand also that high cognitive workloads, often associated with the use of in-vehide devices, may reduce drivers' abilities to process visual information in the roadway environment. I
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