Traffic Stress

Bicycle levels of traffic stress (BLTS) for each relevant road segment within an identified route are drawn from analyses conducted by Delaware Valley Regional Planning Commission (DVRPC) and New Castle County. Alta provides an excellent summary of the traffic stress model for those interested in reading more. BLTS was developed and has been used primarily in urban and suburban settings, and it has yet to be adapted to accommodate conditions more often found in rural settings, like sections with limited sight distance (see below). For sections of the route where we have additional information, we have modified the BLTS model as described below. Every 10' section on the route for which BLTS has been modified is outlined in red.

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A modified BLTS

This used in some cases where additional information is available regarding the likely presence of sections with limited sight distance (see below) or actual prevailing speeds and/or volumes based on traffic studies (these models otherwise use posted speed limits and estimated volumes to model traffic stress).

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Limited sight sections

because of the road’s horizontal or vertical curvature, sometimes worsened by shrubs or trees. Drivers may not be able to see far enough ahead to safely pull around cyclists, increasing the risk of accidents.

We used William’s (2021) paper to establish minimum sight distances (i.e., 2 times the stopping sight distance) based on posted speed (or prevailing speed, when these data were available. Because our interest was in perceived stress as well as actual danger, we added 50’ to the minimum sight distance. Whenever a section was suspected, we measured the sight distance and increased the BLTS by 1 point at each 20’ section for which sight distance was an issue.  

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Descriptors are used in the text corresponding to the level of traffic stress as follows: Level 0 - No Stress; Level 1 - Very Low Stress; Level 2 - Low Stress; Level 3 - Moderate Stress; Level  - High Stress. On maps, higher levels of traffic stress are represented using larger circles for each 20' section.