Problem 5: Discussion

What have we learned? We have discovered that the two-lane rural highway analysis method has some difficulty dealing with hamlets. It has difficulty both determining the PTSF and the average travel speed. We know for the hamlet that the PTSF should be 100%. We have over-ridden the methodology’s estimate of 71.6% and entered 100% in the table. The method also seems to underestimate the speed. An analysis based around the TWSC unsignalized intersection analysis procedure leads us to conclude that the average speed through the hamlet should be about 33.3 mph instead of 24.3 as predicted by the two-lane rural road methodology. We have also seen that if we explore an alternate solution strategy of building a bypass there may be a tradeoff involved. The PTSF improves, as does the average speed, but the total travel time across the highway segment is a minute longer due to the extra travel distance involved. Keeping with the original way that the problem was posed, Idaho Transportation Department will have to decide if the extra minute of travel time is a fair tradeoff for the improved perception of highway performance.