Sub-problem 5c: 10-Mile Analysis with a By-Pass

We need to do one more analysis to complete the problem. We should consider what would happen if a bypass were constructed. This is clearly more hypothetical than the foregoing analysis because it is difficult to say exactly how long the bypass would be. However, it is useful to make some reasonable assumptions and review the results.

In Exhibit 1-43 we assumed that the bypass would be at least a mile away from the original highway alignment for the entire one-mile stretch of highway that passes through the hamlet. We assumed that coming southbound the new alignment would leave the original alignment one mile north of the hamlet, follow back-to-back 1-mile radius curves turning 45^o each, so that the bypass was one-mile from the hamlet where the hamlet starts. It would then progress one mile south paralleling the original highway and then return to the old alignment a mile further south following another pair of back-to-back 1-mile radius curves turning 45^o each. The result is that the new highway segment will be 11.1 miles long (11.1=3.5+1.57+1+1.57+3.5) instead of 10. It will be comprised of one 3.5 mile-long segment having a two-way volume of 1,100 vph, a 4.14 mile-long section with 400 vph, and a 3.6 mile-long segment with 500 vph.

Exhibit 1-47 shows the results. The average travel speed with the bypass is higher (50.7 mph versus 47.9) and PTSF is lower (63.7% versus 67.7%). However, the overall travel time is slightly longer (13.1 minutes versus 12.5 to pass through the hamlet) due to the additional 1.1 miles involved.