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Another practical employment of the BCI model is in the evaluation of proposed roadway designs. The following example illustrates how the BCI model can be used to achieve a design that is "bicycle friendly." A two-lane minor arterial with a two-way-left-turn lane (TWLTL) is being widened to a multilane roadway with a raised median and left-turn bays to accommodate the projected increase in traffic volume and improve safety along the corridor. The roadway currently has 1.2-m bicycle lanes and serves as an important link in the bicycle network. The roadway presently operates at bicycle LOS C, which indicates a moderately high compatibility level for bicycling. The projected traffic volume being used for the design is 16,000 vpd, with 8 percent of those vehicles being large trucks. The posted speed limit will be 50 km/h, and the 85th percentile speed is expected to be 60 km/h. The development along the route is mixed commercial, and there are no plans for on-street parking.
Figure 16. Design Example - original proposed design
The original proposed design was developed within a 27-m right-of-way (ROW) and is shown in figure 16. It consists of four 3.4-m travel lanes, a 6.0-m raised median with left-turn bays, a 2.0-m sidewalk on both sides of the street, a planting strip (1.2 m wide) on both sides separating the travel lanes from the sidewalk, and 0.5-m-wide gutter pans. These geometric data and the operational data provided above are shown in the data entry worksheet in figure 11 for Design Example - Original Proposed Design. The intermediate calculations are shown in figure 12 and the results in figure 13. The BCI for this original design is 4.65, reflecting a bicycle LOS E and a very low compatibility level for bicycling.
Since this route is an important link within the bicycle network, this original design is unacceptable for bicyclists. The goal of the local bicycle coordinator is to maintain the bicycle LOS C, which is currently present on the two-lane facility. After discussing the problems with the roadway design engineers, an alternative plan within the same 27-m ROW is developed in which the median width is reduced from 6.0 m to 4.8 m and the planting strip is reduced from 1.2 m to 1.0 m on both sides of the roadway. The additional 1.6 m in width is added to the curb lanes to create 4.2-m-wide lanes as shown in figure 17. This new curb lane width was entered in the data entry worksheet as shown in figure 11 for Design Example - Wide Curb Lane Option. The results, shown in figure 13, indicate that the BCI for this wide curb lane option is 4.25, which results in a bicycle LOS D and reflects a moderately low compatibility level for bicycling. While this design is an improvement over the original design, it still does not meet the goal of maintaining the existing level of compatibility for bicycling (i.e., LOS C).
Figure 17. Design example - wide curb lane option
A third alternative was proposed within the existing 27-m ROW in which the median width remained at 4.8 m, the planting strips remained at 1.0 m, and the curb lanes returned to 3.4 m. The only remaining feature that the design engineers were willing to alter was the sidewalk. By reducing the width of the sidewalks from 2.0 to 1.8 m and combining this width gain with those previously achieved in reducing the median width and planting strip widths, a 1.0-m paved shoulder could be incorporated on both sides of the street as shown in figure 18. These new values were entered in the data entry worksheet as shown in figure 11 for Design Example - Paved Shoulder Option. The results, shown in figure 13, indicate that the BCI for this option is 3.28, which corresponds to a bicycle LOS C, reflecting a moderately high compatibility level for bicycling. This design meets the goal of maintaining the present compatibility level for bicycling and is selected as the most desirable alternative.
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