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OCT 15 "73 1G:11 MN DOT DRRINCRD f.G • Mr. Pat Klaers October 15, 1993 Page 2 As a check on future traffic volumes on T.H. 169 and vicinity, an assumed growth of five percent annually from a base year of 19.90 was made. This assumption Wae taken from au earlier report by Maid Stewart & Associates. A comparison of traffic volumes from the assumed. five percent growth was made against the forecast from the T.H. 101 report. The results were amazingly close. Having made this comparison on traffic volumes, the forecasted traffic volumes can he assumed to he credible. The 1997 traffic volumes used were 31 ,378 vehir.leA per day. Design Hour Selection The Department of Transportation designs highways for 20 years future. This is a reasonable compromise between a facilities useful life, the uncertainties of long range projections, and consequences of inaccurate projections. In conjunction with the 20-year loug Lauge forecast, the Dc aic,ieut builds a highway capable of handling traffic for a Design Hour Volume (DHV). This is typically the 30th highest hourly volume expected for the year. Thirtieth highest hours vary from roadway to roadway dependent upon function and location. Trunk Highway 169 is a very seasonal route since it serves the vacationland of much of northern Minnesota. Design Hour Volumes for seasonal routeA often Ayneed 20 percent of the average daily traffic (AT)T) and can even • approach 30 percent of the ADT. Without conducting an indepth analysis of what would be an aceturate DHV for T.H. 169 and School Street intersection, we evaluated a peak Friday afternoon peak hour. This selection was for the purpose of studying operations during the busiest time of the day. Utilizing information from a Automatic Traffic Recorder (ATR) located east of Elk River on T.H. 10, we found a peak afternoon hour on Friday in July Co • be slightly greater than 9 percent of the total traffic on that Friday. Overall, a July Friday afternoon peak hour slightly exceeds IL percent of the ADI. Since the volumes on a summer Friday afceruuou peak hour: are less than an expected 30th highest hour volume, we feel our evaluation of a summer afternoon peak hour is representative of a significant number of hours throughout the year. Findings & Conclusions, A summary of the results of our analysis is as follows. ii The Department of Transportation utilizes the 30th highest traffic volume of the year in its design otudico. For this rcaaon, we utilized a time of day and day of week nearing, or less than, the 30th highest traffic volume for studying impacts to T.H. 169. >> A summer Friday afternoon peak hour was selected for our analysis. The design hour traffic used was approximately 11 percent of the ADT and is actually less than an expected 30th hour DHV on this type of facility. >> We derived design hour characteristics from en ATR in close proximity to this intersection. These findings were applied to forecasted traffic volumes. 4111