In response to comments we received during the public outreach, we completed an updated traffic study.

1. May 15, 2020
Mr. Zack Graham
Cushing Terrell
411 E. Main St. #101
Bozeman, MT 59715
Reference: Montana Heritage Center – Capitol Campus Traffic Study
Dear Zack:
The purpose of this letter is to report on traffic volumes on and around the Montana State Capitol
Campus in Helena in order to evaluate the effects of the proposed closure of East 6th Avenue
between North Roberts Street and North Sanders Street due to the expansion of the Montana
Historical Society museum. The closure restricted vehicular traffic from using the street.
Miovision Scout traffic data collection cameras were set up at several locations surrounding the
Capitol Campus before and after the closure of East 6th Avenue. The locations for data collection
were agreed-upon through discussions with the City of Helena (see Figure 1, attached). Traffic data
collection was performed on Wednesday, February 19th, 2020 and Tuesday, February 25th, 2020
before the street was closed, and Tuesday and Wednesday, March 3rd and 4th, 2020 after the street
was closed. Peak traffic hours were found to occur from 7:30-8:30 AM and 4:30-5:30 PM before and
after the East 6th Avenue closure. The intersections of North Roberts Street/East 6th Avenue,
North Sanders Street/9th Avenue, and North Roberts Street/9th Avenue were counted for 24
hours in order to calculate average daily traffic (ADT) volumes on each leg of the intersections.
Figure 1 shows the study locations with color coding to note which intersections were processed for
24 hours and which were processed just during peak hours. Intersections 3, 4, and 7 were processed
for 24 hours to monitor shifts in daily traffic due to their anticipated impacts. Traffic volumes from
before and after the East 6th Avenue road closure are shown in Figures 2-3.
Figure 4 shows the ADT and peak hour traffic volume change from before to after the street closure
for each intersection turning movement. In the AM peak hour, it was found that a majority of
eastbound/westbound thru traffic on the closed section of East 6th Avenue still utilized
intersections 7 and 8 during the road closure. At intersection 7, instead of exiting the intersection to
the east, traffic dispersed in other directions. Approximately 28% rerouted to the north, 19%
rerouted prior (west) of the intersection, and 53% rerouted south. At intersection 8, traffic rerouted
north (62%), rerouted prior (east) of the intersection (29%), and south (9%) instead of west. After
rerouting at intersections 7 and 8, traffic then generally dispersed throughout the rest of the
network.

2. Mr. Zack Graham
May 15, 2020
Page 2
During the PM peak, it was found that only approximately 50% of pre-closure traffic still used
intersections 7 and 8. The rest likely rerouted prior to reaching those intersections. The high volume
of traffic still using those key intersections in the morning could be due to daily routines that drivers
are used to, and they may have forgotten that the road was closed for the short duration. Once the
closure is permanent, it is likely that more traffic would shift from using those intersections
regardless of time period and disperse throughout the rest of the network as people make new
routines. The fact that people were still initially using those intersections after the road closure
predicts that the intersection is operating acceptably and can handle those volumes shifts.
Other areas with notable traffic volume changes on Figure 4 include intersections 1-5. Large
increases and decreases in traffic volumes were seen at intersections 1 and 2. However, these
movements are not related to the East 6th Avenue closure and are likely due to general daily traffic
variation. Additionally, traffic volumes are much higher on N Montana Avenue and 11th Avenue
compared to internal campus street so slight changes in traffic volumes are less impactful at those
corridor intersections. The intersection of 11th Avenue and North Sanders Street can expect an
increase of 161 daily trips from the south of the intersection. Based on the existing street network
connectivity, the current vacancy of the mall site, and the one-way (eastbound) designation of 11th
Avenue, existing traffic heading from the Capitol Campus to the intersection of 11th Avenue and
North Sanders Street are heading to a destination to the east along 11th Avenue and will not be
affected based on the potential removal of the traffic signal. However, with the future connectivity
of North Sanders Street to Prospect Avenue, it is likely some of the traffic on 6th Avenue, 8th
Avenue, and 9th Avenue to the west of Sanders Street that are heading to destinations to the far
west and northwest areas of town will reroute north along Sanders Street across 11th Avenue to
Prospect Avenue.
At intersection 3, an increase in westbound thru and right turns was observed during both peak
hours. The west leg of this intersection can expect an increase of 399 daily trips. During both peak
hours, this was observed as an increase of westbound movements with the eastbound movements
being stagnant. This could be a result of westbound traffic rerouting from intersection 8 likely non-
campus traffic in the AM and campus egress traffic in the PM. These movements do occur on the
stop-controlled approach, but the initial traffic volumes were quite low so it is unlikely that the
observed traffic increase would have a major impact on traffic operations. With the permanent
closure in place and all the traffic rerouting, it is an anticipated 6th Avenue would carry more traffic
than 9th Avenue.
Intersection 4 mainly saw an increase in northbound left turns during both peak hours, and actually
saw a notable decrease in northbound thru movements during the PM peak hour. These changes are
also likely due to traffic rerouting from intersection 8, and they occur on the free-flowing legs of the
intersection so have little effect on traffic flow. It is likely that some vehicles accessed the parking lot
on the northeast corner of intersection 7 through the east leg of intersection 5 instead of from the
closed East 6th Avenue, resulting in some increase in northbound right turns at intersection 5.
Additionally, there was a decrease in northbound thru movements at intersection 5 during the AM
peak and southbound thru movements during the PM peak which could be due to other traffic

3. Mr. Zack Graham
May 15, 2020
Page 3
having already rerouted before reaching the intersection. These impacted movements occur on the
free-flowing legs of intersection 5 and is anticipated to have little impact on traffic flow. Many of
these observed impacts to traffic flow within the network are due to the closure of East 6th Avenue,
but some are also due to other factors like weather (15-20 degrees warmer the second week of data
collection) and general variations in daily driving patterns. Additionally, it is likely some drivers may
have chosen to avoid the Capitol Campus altogether to avoid the road closure.
Pedestrian volumes were not found to be greatly affected as a result of the road closure, but it is
possible that some pedestrian rerouting took place in cases where drivers had to park in a different
location due to the road closure. In general, the magnitudes were small at all intersections. It is
planned that the museum expansion will include a pedestrian crossing through the building, so
impacts to pedestrian behavior are not expected to occur. Based on the 24-hour volumes counted at
intersections 3, 4, and 7, it was observed that the highest pedestrian volumes occur during the lunch
hour, so pedestrian peaks do not overlap with vehicle peaks. ADT volumes were also compared for
the street legs surrounding intersections 3, 4 and 7. Those results can be seen in Table 1 below.
Based on observations of existing traffic movements, existing intersection traffic control, and
analysis of traffic volumes after the closure, it is anticipated the intersections on the Montana Capital
Campus will have minimal impacts to traffic operations with a permanent closure of East 6th
Avenue. These impacts will be small percentages of traffic volumes through adjacent intersections
generally in free-flowing movement with little to no impact on intersection delay or queueing. The
minimal amount of existing traffic using East 6th Avenue as a bypass through the Montana Capitol
Campus will dissipate into adjacent intersections with ease based on our analysis of the temporary
closure. Feel free to contact me with any further questions or comments.
Table 1: ADT Comparison
Intersection Leg
Before Road
Closure
After Road
Closure
Percent
Change
East Leg 2205 319 -86%
West Leg 2393 1507 -37%
North Leg 1372 1486 8%
South Leg 1096 1609 47%
East Leg 1318 1557 18%
West Leg 1086 1784 64%
North Leg 1516 1677 11%
South Leg 1665 2236 34%
East Leg 1114 1777 60%
West Leg 850 1249 47%
North Leg 2069 2126 3%
South Leg 1716 1760 3%
6th & Roberts
(Intersection 7)
9th & Sanders
(Intersection 4)
9th & Roberts
(Intersection 3)

4. Mr. Zack Graham
May 15, 2020
Page 4
Sincerely,
Joey Staszcuk, PE, PTOE
Senior Traffic Engineer
Community Transportation Studio Manager
JHS/ars
Enc.
P:20015_Montana_Heritage_Center_Capitol_Campus_Traffic_Study_051520