When road segments with high traffic stress are excluded, the remaining network of low-stress roads and trails can be fragmented, lacking connections between many origin-destination pairs or requiring onerous detour. Low-stress connectivity is a measure of the degree to which origins (for this study, homes) and destinations (jobs) can be connected using only low-stress links and without excessive detour. Revision 2.0 to Level of Traffic Stress criteria is introduced and applied to the road and trail network of northern Delaware. A propensity model is proposed to reflect people’s declining willingness to ride a bike with greater trip length and detour, accounting for the impact to health and other benefits of cycling. New connectivity measures are introduced that can be interpreted as the number of bike-accessible jobs and the potential number of bike-to-work trips, powerful measures for evaluating alternatives. These connectivity measures are applied in a case study evaluating alternative alignments for a bike route between Wilmington and Newark, Delaware’s two largest cities, separated by a distance of about 20 km through a largely suburban landscape. The case study explores the benefits of enhancing alternatives with branches that help connect to population and employment centers. We also find that the connectivity gain from constructing multiple alignments is greater than the sum of connectivity gains from individual alignments, indicating that complementarity between the alternatives, which are spaced roughly 5 km apart, overshadows any competition between them.

The relationships between plastic zone, pores, fatigue crack growth rate (da/dN), and fracture mechanics parameters of metal injection molding (MIM) 316L stainless steel at various stress ratios (R = 0.1 and 0.4) are investigated in the present work. Using two-dimensional (2D) plane strain finite element analysis (FEA), the stress intensity factor and cyclic-plastic zone at crack tip are evaluated. The slow-growth da/dN at near-threshold regime is in brittle manner, and can be characterized by maximum stress intensity factor (K max ). While, the mid-growth da/dN at Paris regime is in ductile manner, and can be characterized by stress intensity factor range ( K). As a fracture mechanics parameter that combines K max and K, the K* successfully characterizes the stress ratio effect on FCG rate at near-threshold and Paris regimes. The transition from slow-growth da/dN to mid-growth da/dN occurs when the cyclic-plastic zone at crack tip coalesces with pore. The appearances of fracture surfaces at near-threshold and Paris regimes are in good agreement with the FEA results.

Low-stress bike networks are often disconnected, with gaps or barriers that make travel between two points impossible without riding on high-stress roads. Barriers can also force long detours that people are not willing to make. Although existing methods of low-stress bike network analysis have been used to point out some barriers, a method was needed to systematically identify and draw barriers to assist in network planning. Such a method was developed, taking only the low-stress network as an input, and yielding a set of polylines that indicated barriers to bicycling. Applications in Arlington, Virginia and Boston, Massachussets showed how it detected what might otherwise have been hidden barriers. The method also successfully highlighted critical low-stress links that breached what would otherwise have been a far longer barrier.

One-way restrictions on local streets, which tend to have low traffic stress, can create a significant barrier to low-stress cycling. Contraflow, a treatment that undoes one-way restrictions on bike travel, has the potential to improve low-stress connectivity. Although contraflow is applied routinely in the Netherlands and Belgium, it has been sparingly applied in the United States. We propose refined measures of connectivity and accessibility that account for one-way restrictions by requiring a low-stress round trip path between origins and destinations. Different methods of associating origin–destination demand from polygons with a street network were analyzed. These methods are particularly important where there are one-way restrictions and irregular street networks because of the assumptions they entail in relation to first- and last-segment travel. In a case study of Greater Boston, we found that with the current bike network, low-stress connectivity between homes and jobs would increase from 1.2% to 8.7% if one-way restrictions on local streets were eliminated. We also found that even with a dense mesh of low-stress main bike routes, connectivity would still be 16% lower without contraflow on local streets than with. These results suggest that creating a network of main bike routes is not always enough; it is also important to provide contraflow on local streets. The Boston study also found that providing contraflow on selected links representing only 3% of local one-way street mileage delivered 40% of the connectivity impact of universal contraflow. Based on this finding, a method is proposed for prioritizing streets for contraflow conversion.