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HomeMy WebLinkAbout13 Nexus Graf Site TIS Review Comments 11-25-19 MARVIN & ASSOCIATES 1300 N. Transtech Way Billings, MT 59102 Mailing Address: P.O. Box 80785 Billings, MT 59108-0785 Phone: 406-655-4550 FAX: 406-655-4991 Email: bobm@marvinassociates.com Chris Budeski, P.E. Madison Engineering November 25, 2019 Re: 2131 Graf Site Traffic Impact Study Review I have evaluated the City of Bozeman’s August 15, 2019 review comments on the above noted project and have developed the following comments and questions as listed for items 17 through 29: 17. I don’t have any information regarding responsibility for completing S 21st Avenue. 18. Page 3 – The word south will be changed to north. 19. Page 9 - The 10% estimate for bicycle/pedestrian trips has been typical for studies we have completed in the Bozeman area where residential subdivisions are not remote from the urbanized area. The 10% estimate reflects the 2010 census data for work trips by mode, which indicates that 5% of work trips are by bicycle and 9% are made by walking in the Bozeman urbanized area. From past studies that we completed in downtown Bozeman, it was found that those numbers are substantially higher. For this study location, we went with 10% instead of the 14% (census data) because the site is not completely surrounded by urban development and would therefore be less likely fall into the average of the range, even though the proximity to the MSU campus would encourage higher than average bicycle usage. We will insert a brief wording in the final report in support of this estimate. 20. Page 9 - I am totally familiar with the ITE Trip Generation User’s Guide. The combined size of both subdivisions at this site is approximately 200,000 square feet, which is within the ITC criteria range. The ITE document doesn’t specifically exclude this type of development, but it doesn’t include data related to anything other than residential, retail, and office uses. In this case, the mixed use involves a community center which includes services tailored to the needs of the apartment dwellers, such as open space, a pool, and a club house. When considering that the apartments would most likely be occupied by younger age residents, the community center has the potential to attract a substantial number of trips. Thus, the 5% approximation is felt to be warranted. I will add wording in justification of this estimate. 21. Page 12 – It should be made clear that the apartment complex will not be leased exclusively by students or workers at MSU and lacking any kind of projection on how many students and MSU workers will occupy the apartments, the most accurate method of distributing traffic is to mirror travel patterns from adjacent residential developments as explained on page 11. Disaggregation of directional movements at surrounding intersections results in a valid and dependable method of determining the relatively travel demand that exists from an origin to external destinations. This method is especially accurate during peak am and pm hours. The distribution percentages shown in Figure 3 were not extended beyond the study MARVIN & ASSOCIATES 1300 N. Transtech Way Billings, MT 59102 Mailing Address: P.O. Box 80785 Billings, MT 59108-0785 Phone: 406-655-4550 FAX: 406-655-4991 Email: bobm@marvinassociates.com area so that you don’t actually see that the 43% north of Kagy would actually include trips that go to or come from the campus on Lincoln Street and on College Street. Ten percent of the trips would be destined to MSU on S 11th Avenue and all of the 4% trips on the Campus Boulevard extension would be destined to MSU. All things considered, trips appearing as traffic on MSU Campus Streets would probably be about 44%. This indicates that the MSU Campus would be a major attraction for trips to and from the site development. I will provide additional explanation in the report. 22. Page 12 – With regard to the traffic assignment for the eastbound left turns from the site onto S 19th Avenue, I did not indicate directional distribution of turns at intersection on Figure 3. In actuality, 11% of the trips would be directed to the south and 57% would be direct to and from the north. Site access distributions are based on the least travel time paths from the internal subdivision streets to and from the adjacent streets. All of the site access distributions are based on “Unconstrained” conditions, where intersection delays based on capacity constraints are not considered in traffic distribution. Operational constraints are considered in the final traffic assignment analysis. It should also be noted that the term “unprotected left” movements only apply to traffic signals. In this case, the left turn is only protected by a stop sign, the same as all other movements from the access. I will add turn movement percentages to Figure 3 to avoid confusion. 23. Page 12 - The intersection of Discovery Drive and Arnold Street would only serve trips with an origin or destination on to Stuckey Road (4% of total) and the only segment of the site development that would benefit from routing through the local streets to Stuckey Road would be a small segment of the northwest corner of the Nexus Subdivision representing about 5% of the total development. The distribution on Discovery Lane would then amount to approximately 0.2% trips which would be 6 vehicles on the average weekday and 0.5 vehicles in the peak pm hour. It would be ludicrous to include this intersection in the impact analysis for less than one additional vehicle in the peak pm hour. 24. Page 13 - The assumption that the Campus Boulevard extension was based on our knowledge that the project is in the final stages of design and there is a high probability that construction will begin in the year 2020. From experience, it is understood that it will take between 2 and 3 years before any significant development occurs within the study site. If the Campus Boulevard extension is not completed within the next 2 to 3 years, it would likely be due to economic conditions which would also affect the construction schedule of the study development. For these reasons, I believe that the assumption is valid. If necessary I can redo the distribution, traffic assignment, and capacity calculations, but it seems to be a lot of expense to reassign 10 vehicles in the peak pm hour which will not appreciably change any of the study conclusions. 25. Page 15 – Table 3 has three columns for each approach that present capacity calculation results for three Measures of Effectiveness (MOE), as explained MARVIN & ASSOCIATES 1300 N. Transtech Way Billings, MT 59102 Mailing Address: P.O. Box 80785 Billings, MT 59108-0785 Phone: 406-655-4550 FAX: 406-655-4991 Email: bobm@marvinassociates.com on page 8. The first column is the average delay per vehicle, which is 14.3 seconds. The second column is the level of service (LOS) designation based on average delay criteria, which for the eastbound movement in the AM peak hour is “B”. The third column is the maximum number of vehicles stored (stopped & waiting) in the queue, based on the 95% confidence interval, rounded upward to an even number of vehicles, which in this case is 1. To determine if the correct number of vehicles for the approach was entered into the calculations, please go to Appendix B in the report. 26. Page 17 - Table 3 shows each movement applicable to analysis using the Highway Capacity Manual Software. In the case of S 19th Avenue and Arnold Street, the intersection is a “T” intersection that only has three approaches (eastbound, northbound, and southbound). Capacity calculations are only applicable to vehicle movements that have conflicts that result in delay. In this case those movements would be eastbound left turns and right turns, and northbound left turns. All other movements are free-flow uncontrolled movements on the arterial street. Please refer to Appendix B to see the calculation inputs and results. 27 Page 19 - We will provide a list of studies and developments that were in included in the future traffic projections. 28 Page 20 - We will correct the typo on Figure 7. 29 Appendix A Traffic Count Data - I am not exactly sure of what you mean by saying that the trip rate for the generator is equal to or greater than the trip rate for the peak am and pm hours. In questioning the justification for the counting periods, I think you may be confusing the counting period with the peak hour volumes within the counting periods. We have past studies where traffic counters provided hourly count data for 24 hours per day. From those counts it was determined that the typical peak hour periods fall within the two hour Mio-vision counting periods taken in the morning and evening. Justification for the periods are based on current state-of-the-art practices based on hundreds of traffic engineering manuals and standard procedures developed by ITE, AASHTO, and other publications. Peak hours are defined as the sum of 4 consecutive 15 minute periods that produce the highest volumes of traffic entering the intersection during the peak counting period. Capacity calculations use the highest 15-minute period of the peak hour. Thus, input to the software uses the peak hour factor (PHF) which is: Total entering vehicles divided by 4 times the peak 15-minute entering volume. If there are any other clarifications or information required, feel free to contact me. Robert R. Marvin, P.E., P.T.O.E.