01-29-20 Technical Advisory Committee Agenda
Planning Department
201 1st Avenue East
Kalispell, MT 59901
Phone: (406) 758-7940
Fax: (406) 758-7739
www.kalispell.com/planning
KALISPELL TECHNICAL ADVISORY COMMITTEE
The Kalispell Technical Advisory Committee (TAC) will meet on Wednesday
January 29, 2020 starting at 1:30 p.m. in the MDT 2nd Floor Conference
Room at 85 5th Avenue EN in Kalispell. A final agenda is provided below.
The agenda for the meeting will be:
A. Call to order and roll call
B. Approval of minutes of November 20, 2019 meeting
C. Comments from the Public
D. Continuation of discussion with MDT and engineering consultants KLJ to
complete design work on the final segment of the US Highway 93 Bypass
from US 93 South through the Airport Road Roundabout. MDT and KLJ will
present various intersection options for widening the KBP, US 93 to Airport
Road project. The options will focus on an interchange at Airport Road and
interchange or as-is options as Basecamp Drive. A summary report will be
provided in the advance packet. A project open house is scheduled for
January 30, 2020 to share this information with the public and hear their
thoughts.
E. Old Business
F. New Business
- Update on status of area highway projects by MDT, Flathead County and
Kalispell.
F. Appointment of new committee chairperson
G. Setting next meeting date
H. Adjournment
Page 1
KBP: Traffic Memorandum #3
Date: 1/20/2020
To: Fred Bente, MDT Consultant Manager
From: Kathy Harris, PE, PTOE, Joe DeVore PE, PTOE, and Oz Khan, EIT
RE: 2038021 KBP: US 93 to Airport Road, Traffic Operations and Safety Analysis
Executive Summary
Traffic operations and safety analysis were performed along the Kalispell Bypass (KBP) at Airport Road and
Basecamp Drive to compare proposed combinations of intersection improvements. The traffic and safety
analysis showed high benefits for both traffic operations and safety for all alternatives except the No Build.
The alternatives are a combination of various concepts for the two intersections and were used to show
the overall network operations. Table 1 ranks alternatives for safety and operations. With all build
alternatives having a substantial right-of-way and cost impact, the traffic and safety benefits outlined in
this report will only be part of the selection of the preferred alternatives at Airport Road and Basecamp
Drive.
Table 1: Traffic Operations and Safety Rankings
Alternative
(Figure #)
Airport
Road
Description
Avg
Delay
Rank
VMT
Rank
Airport Road
Safety Rank
Basecamp Drive
Safety Rank
No Build 7 1 7 7
Alt 1A (Figures #1/#9) RABs 5-leg 1 6 5 5
Alt 1B (Figures #2/#9) RABs 4-leg 2 5 4 6
Alt 2A (Figures #4/#7) SE Loop
RAB 2 3 1 2
Alt 2B (Figures #3/#7) SE Loop TS 6 2 3 2
Alt 3 (Figures #5/#8) SW Loop TS 5 7 2 1
Alt 4 (Figures #2/#6) RABs 4-leg 4 4 5 4
This memorandum presents the existing and year 2045 traffic operations and safety analysis for a
comparison of KBP intersection and interchange configurations. The study area includes the KBP between
US 93 and Airport Road and the intersection of Airport Road and Cemetery Road. The remainder of this
memorandum presents the analysis summarized in Table 1.
Page 2
Existing Traffic Operations
Methodology
Vehicular traffic operations were analyzed at the study intersections. Intersection capacity analysis was
evaluated in terms of delay and level of service (LOS). LOS is a term used to describe the operational
performance of transportation infrastructure elements; it assigns a grade value that corresponds to
specific traffic characteristics within a given system, as shown in Table 2. At intersections, LOS is a function
of average vehicle delay, whereas LOS for a roadway section is defined by the average travel speed. LOS
“A” represents free flow traffic whereas LOS “F” represents gridlock. LOS “E” or worse is considered
deficient, in accordance with the engineering standards. Capacity analysis was conducted using PTV
VISSIM microsimulation software, which simulates the movement of every vehicle through an intersection
and then collects information for associated performance measures like delay, queue lengths, travel
times, and density.
Table 2: Intersection Control Delay and Level of Service
Level of
Service (LOS)
Average Delay (seconds/vehicle)
Unsignalized Roundabout Signalized
A ≤ 10 ≤ 10 ≤ 10
B > 10 and ≤ 15 > 10 and ≤ 15 > 10 and ≤ 20
C > 15 and ≤ 25 > 15 and ≤ 25 > 20 and ≤ 35
D > 25 and ≤ 35 > 25 and ≤ 35 > 35 and ≤ 55
E > 35 and ≤ 50 > 35 and ≤ 50 > 55 and ≤ 80
F > 50 > 50 > 80
No Build Traffic Operations Analysis
Existing 2019 Traffic Operations
The existing 2019 traffic operations evaluated AM and PM peak hour conditions under current traffic
volumes. Under existing conditions, the Airport Road and Cemetery Drive intersection experiences
unacceptable delays with intersection LOS D and westbound traffic on the minor approach showing
LOS F in the PM peak. All other intersections and approaches operate acceptably at LOS C or better during
both AM and PM peak hours. Detailed results can be found in Attachment A.
Corridor Travel Times
Corridor travel times on the KBP were calculated based upon a 1.5-mile segment from US 93 to west of
Airport Road. The free flow travel time segment (no delay) at 55 miles per hour for the corridor is 1 minute
and 38 seconds for the 1.5-mile segment. During the AM peak hour, the travel time is 2 minutes and 10
seconds, or 32 percent higher than free flow travel time, in both directions. During the PM peak hour, the
travel time is 2 minutes and 12 seconds, or 34 percent higher than free flow travel time in both directions.
2045 Traffic Operations
The 2045 traffic operations evaluated AM and PM peak hour conditions under 2045 projected traffic
volumes, as discussed in Traffic Data Memorandum #2. Under 2045 projected conditions, three of four
intersections experience operational deficiencies with unacceptable intersection delays.
Page 3
• AM Peak Hour
o Airport Road and Cemetery Drive is expected to operate at LOS B, with the westbound
approach at LOS F.
• PM Peak Hour (15% of vehicles unable to enter the model)
o US 93 and KBP is expected to operate at LOS E, with the northbound and eastbound
approaches deficient at LOS E and F, respectively.
o KBP and Airport Road is expected to operate at intersection LOS C, with the northbound
KBP approach deficient at LOS F.
o Airport Road and Cemetery Drive is expected to operate at LOS F, with the westbound
minor approach showing over 5 minutes delay per vehicle. There is very little delay on the
northbound and southbound approaches, but the poor operations on the westbound
approach impact overall intersection level of service.
Corridor Travel Times
During the 2045 AM peak hour, the eastbound travel time is expected to increase to 2 minutes and 17
seconds (40 percent higher than free flow), and the westbound travel time is expected to be 2 minutes
and 11 seconds (33 percent higher than free flow). During the 2045 PM peak hour, the eastbound travel
time is expected to be 2 minutes and 19 seconds (41 percent higher than free flow) while the westbound
travel time is expected to be 3 minutes and 39 seconds (123 percent higher than free flow).
Safety Analysis
Three years of crash records (January 1, 2016 to December 31, 2018) were obtained from Montana
Department of Transportation (MDT) to analyze historic crash data since the KBP has opened and to
identify existing safety deficiencies. This data was sorted and matched to four intersections along the
corridor or as part of six unique corridor segments. During the three-year analysis period, a total of 94
crashes (26 Injury, and 68 Property damage crashes) occurred in the study area. There were no fatal
crashes reported during this period. These crashes represent $2.3 million in crash costs per year based on
2016 FHWA Highway Safety comprehensive crash unit costs. The crash summary is shown in Table 3.
Table 3: Crash Summary Year: 2016-2018
Intersection Intersection Total Crashes
KBP & US 93 Signal 42
KBP and Siderius Intersection Other 3
KBP and Airport Road Other 8
Airport Road and Cemetery Road Rural Thru/Stop 19
Segment Roadway Section Total Crashes
US 93: KBP to Cemetery Road 5-lane Undivided 6
KBP: US 93 to Airport Road 2-lane Undivided 9
KBP: West of Airport Road 2-lane Undivided 5
Airport Road: South of KBP 2-lane Undivided 1
Airport Road: North of KBP 2-lane Undivided 0
Cemetery Rd: Between Airport Rd and US 93 2-lane Undivided 1
Grand Total 94
Page 4
Elevated Crash Rate
To identify overrepresented crash locations within the study area, crash rates were used to address which
intersections had the highest crash rate to traffic volume ratio. This helps identify intersections that may
have fewer overall crashes, but on a per car basis, a much higher rate of crashes.
According to the crash rate analysis, intersections and segments with crash rates above 1 crash per million
entering vehicles (MEV) are considered overrepresented and in need for further review; there is a high
probability that conditions at the site are contributing to the higher crash rate. The intersections and
segments with crash rates below critical crash rates indicates that these areas are currently not a major
safety concern.
• The intersections of KBP and US 93 and Airport Road and Cemetery Road have crash rates above
1 crash per MEV.
Crash Trends
Intersections
The KBP and US 93 intersection experienced elevated crash rates with 42 crashes (11 injury related) during
the analysis period. This corresponds to 14 crashes including four injury related crashes per year. Rear end
crashes (37) were the most common type of crash at the intersection likely due to the increased
congestion at the existing signalized intersection.
The Airport Road and Cemetery Road intersection experienced 19 total crashes (10 injury related) during
the three-year analysis. Eleven of these crashes were angle related and 5 were rear end related. The
existing high-speed stop-controlled intersection does increase the probability of an injury related crash.
This is confirmed by over 50% of existing crashes resulting with injuries.
Surrogate Safety Assessment Model (SSAM)
Methodology
Analyzing historic crash data is a reactionary approach to roadway safety. The Surrogate Safety
Assessment Model (SSAM) takes a proactive approach to crash prediction along roadways. SSAM uses PTV
VISSIM vehicle trajectory files to analyze vehicle-to-vehicle interactions to identify conflict events and
near-miss conflicts for future intersection configurations and volumes. Analysis is based on velocity,
deceleration, gap acceptance, volumes, and site-specific vehicle paths to quantify predicted conflicts for
rear-end, crossing, and lane change types. Crossing conflicts are used to analyze if serious injury type
crashes are increasing or decreasing as these conflicts generally have the highest speed differential
between vehicles and occur at the most severe angles.
The SSAM analysis identifies significantly more conflicts than is reflected in historical or actual crash data.
The validation efforts FHWA has completed show comparable correlation between SSAM and more
traditional crash prediction models, however SSAM provides a much lower variance in results. While the
quantity of conflict points can sometimes be misleading, the percentage change between scenarios gives
a very detailed investigation into the safety improvements being considered and can be used to assess
the future safety of the corridor similar to crash modification factors. However, SSAM identifies potential
conflicts based on the site-specific characteristics, so it can more accurately predict the expected changes
to safety and conflict potential than generic crash modification factors.
Page 5
Existing and 2045 No Build Scenario SSAM Conflict Analysis
The AM and PM peak hour PTV VISSIM microsimulation results were used to complete the SSAM conflict
analysis for the existing and 2045 no build scenario. Table 4 summarizes the SSAM results for the Existing
and No Build conditions.
Table 4: SSAM Conflict Analysis Results for No Build 2019 and 2045
SSAM Conflicts per Peak Hour
2019
Existing
AM
2045 No
Build AM
2019
Existing
PM
2045 No
Build PM
SSAM
Results
Existing
Crash % Total 60 225 116 515
20% Crossing 21 35% 27 12% 24 20% 32 6%
48% Rear End 24 40% 109 48% 63 55% 279 54%
6% Lane Change 15 25% 89 40% 29 25% 204 40%
During the AM peak, rear end conflicts are expected to increase more than 350 percent from 2019 to 2045
due to increased traffic volumes. Lane change conflicts are also expected to increase nearly 500 percent
mostly due to the four-lane conversion. During the 2019 PM peak, rear end conflicts and lane change
conflicts are expected to increase similarly. With rear end crashes already being identified as a problem
from historical crash data, this crash rate is expected to escalate as traffic volumes continue to grow along
the bypass. Crossing conflicts are only expected to increase by about 30 percent which only represents
the Airport Road and Cemetery Road intersection due to other roundabout intersections generally
consisting of only rear end and lane change conflicts merging and diverging from the existing roundabout.
This shows that Airport Road and Cemetery Road will likely continue to see its existing severity rate
increase. The 2045 No-Build SSAM conflicts are used as the baseline to compare future alternatives.
Alternatives Analysis
The KBP is proposed to be widened from two to four through lanes in the study area. Alternatives were
developed for the Airport Road and Basecamp Drive intersections on KBP within the study area.
Alternatives are shown in Figures 1-9 and were combined into cohesive segments which were analyzed
for 2045 traffic operations and safety analysis. Detailed results for each alternative combination can be
found in Attachment B with Table 5 and Table 6 summarizing traffic operations and safety comparisons.
Figure 1 – Airport Road 5-Leg Diamond Roundabouts
Figure 2 – Airport Road 4-Leg Diamond Roundabouts
Figure 3 – Airport Road 5-Leg SE Loop North Signal
Figure 4 – Airport Road 5-Leg SE Loop with North Roundabout
Figure 5 – Airport Road 4-Leg SW Loop with Signals
Figure 6 – Basecamp Drive Quadrant Interchange
Figure 7 – Basecamp Drive NW Extend Quadrant Interchange
Figure 8 – Basecamp Drive SW Loop Diamond Interchange
Figure 9 – Basecamp Drive Existing Roundabout
Page 6
Figure 1 – Airport Road 5-Leg Diamond Roundabouts
Page 7
Figure 2 – Airport Road 4-Leg Diamond Roundabouts
Page 8
Figure 3 – Airport Road 5-Leg SE Loop North Signal
Page 9
Figure 4 – Airport Road 5-Leg SE Loop with North Roundabout
Page 10
Figure 5 – Airport Road 4-Leg SW Loop with Signals
Page 11
Figure 6 – Basecamp Drive Quadrant Interchange
Page 12
Figure 7 – Basecamp Drive NW Extend Quadrant Interchange
Page 13
Figure 8 – Basecamp Drive SW Loop Diamond Interchange
Page 14
Figure 9 – Basecamp Drive Existing Roundabout
Page 15
Alternative 1A (Figures #1 and #9) and 1B (Figures #2 and #9): Roundabouts at Airport Road
and Basecamp Drive
Alternative 1 would maintain the existing 2x1 lane roundabout at Basecamp Drive and construct a
diamond interchange with roundabouts at the Airport Road intersection. Alternative 1A would be
constructed with a 5-leg roundabout including northbound on- and off-ramps with Cemetery Road, while
Alternative 1B would eliminate the northbound off-ramp to create a 4-leg roundabout which is the current
concept from the 2006 environmental document. The eliminated movements off the KBP for Alternative
1B were reassigned to the Basecamp Drive intersection.
Alternative 2A (Figures #4 and #7) and 2B (Figures #3 and #7): Interchange with Southeast
Loop Ramp at Airport Drive and Expanded NW and SE Quadrant Interchange at Basecamp
Drive
Alternative 2 would construct interchanges at both Airport Road and Basecamp Drive. At Airport Road,
the interchange would include a 5-leg roundabout (Alternative 2A) or a 5-leg signal (Alternative 2B) north
of KBP to combine the northbound on- and off-ramps with the nearby intersection of Airport Road and
Cemetery Road. South of KBP at Airport Road, the interchange would include a loop ramp for the
southbound off-ramp at a two-way stop with right turn bypass and a new ramp for the southbound on-
ramp. Basecamp Drive would be elevated above the KBP with right-in, right-out (RIRO) access from KBP.
Basecamp Drive would build new two-way stop intersections for full access movements in both directions.
Alternative 3 (Figures #5 and #8): Southwest Loop and Signals at Airport Road and
Southwest Loop at Basecamp Drive
Alternative 3 would construct interchanges at both the Airport Road and Basecamp Drive intersections.
At Airport Road, the interchange uses a loop ramp in the southwest quadrant for the southbound off- and
on-ramp movements and signalizes both ramp termini. The northbound off-ramp would not be built, and
the northbound on-ramp would be combined with the Cemetery Road intersection and signalized.
Basecamp Drive would be elevated above the KBP with ramp access from KBP with acceleration and
deceleration lanes. Basecamp Drive would build new two-way stop intersections for full access
movements in both directions.
Alternative 4 (Figures #2 and #6): Diamond Interchange with Roundabouts at Airport Drive
and NW and SE Quadrant Interchange at Basecamp Drive
Alternative 4 would construct a diamond interchange with roundabouts at the Airport Road intersection
and an interchange at Basecamp Drive. At Airport Road, the northbound KBP off ramp would not be built.
The northbound KBP on ramp would be combined with the Cemetery/Airport roundabout in a standard
4-leg configuration. Basecamp Drive would be elevated above the KBP with right-in, right-out (RIRO)
access from KBP. Basecamp Drive would build new two-way stop intersections for full access movements
in both directions.
Page 16
Network Results 2045 No Build Alternative 1A Alternative 1B Alternative 2A Alternative 2B Alternative 3 Alternative 4
Total Vehicles 4,159 4,156 4,165 4,177 4,178 4,214 4,211
Avg Delay (s/veh)31.6 10.7 13.0 14.8 17.2 17.0 15.5
Latent Demand 0 0 0 0 0 0 0
VHT (hours)160 142 145 138 139 143 144
VMT (miles)5937 6430 6424 6086 6081 6441 6278
Travel Time Results
WB KBP Travel Time (min)2.29 1.87 1.87 1.65 1.65 1.64 1.60
EB KBP Travel Time (min)2.18 1.87 1.87 1.59 1.59 1.58 1.59
Intersection Delay (secs)
US 93 and KBP 21.9 7.3 10.6 12.6 12.6 13.3 12.9
KBP and Basecamp 3.2 2.1 2.0 5.7 5.7 3.8 6.1
KBP and Airport Rd / S Termini 4.6 2.1 2.1 1.3 1.3 14.0 1.9
Airport Rd and Cemetery Rd / N Termini 13.1 2.2 1.8 1.9 13.9 6.6 2.3
Network Results 2045 No Build Alternative 1A Alternative 1B Alternative 2A Alternative 2B Alternative 3 Alternative 4
Total Vehicles 4,746 5,681 5,700 5,700 5,699 5,753 5,746
Avg Delay (s/veh)195.7 13.5 17.6 16.5 20.5 19.5 17.8
Latent Demand 708 0 0 0 0 0 0
VHT (hours)425 200 206 192 197 201 201
VMT (miles)6869 8799 8750 8324 8317 8814 8592
Travel Time Results
WB KBP Travel Time (min)2.31 1.89 1.88 1.65 1.65 1.64 1.60
EB KBP Travel Time (min)3.65 1.88 1.89 1.60 1.60 1.59 1.60
Intersection Delay (secs)
US 93 and KBP 55.6 9.1 14.9 13.1 13.1 13.8 13.4
KBP and Basecamp 6.3 2.8 2.5 6.5 6.5 4.2 8.7
KBP and Airport Rd / S Termini 15.6 3.6 3.7 2.3 2.3 19.1 3.2
Airport Rd and Cemetery Rd / N Termini 77.3 4.2 3.3 3.5 22.2 10.0 4.8
AM Results
PM Results
Table 5- 2045 Traffic Operations Alternative Comparison
Page 17
2045 Traffic Operations Analysis
Several metrics for traffic operations were quantified for each alternative and shown in Table 5. Network
results were used to understand total average vehicle delay, vehicle hours traveled (VHT), and travel
distance (VMT). KBP eastbound and westbound travel time were also quantified to show benefits for the
principal arterial. Lastly, each alternative compared the delay for Basecamp Drive assuming the entire
interchange while Airport Road analyzed the north and south intersections separately because of
Cemetery Road.
2045 traffic operations showed that all alternatives provided a significant benefit over No Build operations
in Average Delay, VHT, and KBP travel times. Alternatives 1A and 1B provided lowest network delays
throughout the day but these alternatives also added 15 seconds of travel time to eastbound and
westbound KBP movements because of the existing roundabout at Basecamp Drive. VMT was minimized
for Alternatives 2A and 2B due to the full access interchange at Airport Road not diverting traffic to
Cemetery Road. Intersection results also showed that signalized intersections in Alternative 2B and 3
increased delay by 500 to 700 percent compared to roundabout alternatives.
2045 SSAM Conflict Analysis
2045 SSAM conflict analysis was quantified for each alternative and compared to the No Build conditions
in Table 6 to show the estimated safety benefit. Below is a summary of the results:
• With both No Build intersections being roundabouts, crossing conflicts did not change much with
the interchange build alternatives. It is expected that roundabout terminals will reduce serious
injury crashes due to decreasing high-speed and high-angle conflicts found in signalized and two-
way stop alternatives.
• Alternative 2A and 2B are further expected to improve total safety and severe safety by converting
a diamond interchange minor left-turn into a channelized right-turn with the south-east loop.
• Both rear end and lane change conflicts were improved significantly due to the grade separations
and removal of KBP through traffic from each existing intersection.
• For Airport Road, Alternative 2A (Figure #4) provided the highest conflict reduction.
• For Basecamp Drive, Alternative 3 (Figure #8) provided the highest conflict reduction by providing
a full interchange. Alternative 2 (Figure #7) also provided a major safety benefit (85% reduction
in conflicts) compared to No Build conditions.
Page 18
2045 No
Build Alt 1A Alt 1B Alt 2A Alt 2B Alt 3 Alt 4
Total 81 5 3 2 4 2 5
Crossing 2 0 0 0 1 2 0
Rear End 46 2 2 1 2 1 3
Lane Change 33 3 1 1 1 0 2
Total Rank 8 4 3 1 5 2 6
AM Results at Airport Road/Cemetary RoadSSAM Conflicts
(AM Peak Hour)
2045 No
Build Alt 1A Alt 1B Alt 2A Alt 2B Alt 3 Alt 4
Total 44 19 20 7 6 2 7
Crossing 0 0 0 4 4 1 5
Rear End 14 9 10 2 2 1 1
Lane Change 31 10 11 1 1 0 0
Total Rank 8 6 7 4 3 1 2
SSAM Conflicts
(AM Peak Hour)
AM Results at Basecamp Drive
2045 No
Build Alt 1A Alt 1B Alt 2A Alt 2B Alt 3 Alt 4
Total 111 15 12 4 11 11 15
Crossing 3 0 0 0 2 3 0
Rear End 61 6 7 1 9 8 9
Lane Change 48 9 4 3 1 0 6
Total Rank 8 2 3 1 5 4 6
PM Results at Airport Road/Cemetary RoadSSAM Conflicts
(PM Peak Hour)
2045 No
Build Alt 1A Alt 1B Alt 2A Alt 2B Alt 3 Alt 4
Total 68 32 33 9 10 4 15
Crossing 0 0 0 7 7 2 6
Rear End 30 19 16 1 2 1 9
Lane Change 38 13 16 1 1 0 1
Total Rank 8 7 6 2 3 1 5
PM Results at Basecamp DriveSSAM Conflicts
(PM Peak Hour)
Table 6 – 2045 SSAM Safety Alternative Comparison
Page 19
Alternative 2A and 2B Sensitivity Analysis
Alternative 2A (Figure #4/Figure #7) and Alternative 2B (Figure #3/Figure #7) include a 5-leg intersection
north of KBP. To ensure this intersection can handle accelerated traffic growth or spikes in traffic, a
sensitivity analysis was completed. This sensitivity analysis increased traffic using KBP and the
interchanges during the 2045 PM peak hour by 30 percent.
Ultimately, Alternative 2A (5-Legged roundabout) provides better operations by 264% at Airport Road
under the sensitivity scenario, but both alternatives operative acceptably at LOS C or better. This
operations analysis benefit for roundabouts versus signals would be similar for all 5-leg alternatives at the
Airport Road/Cemetery Road/North KBP ramp termini. Total and crossing conflicts also show that the
roundabout alternative provides 4.8 times the conflict reduction than the signalized alternative. Results
at Basecamp Drive show that the existing roundabout’s northbound approach becomes deficient with the
30 percent additional traffic.
Table 7 - Alternative 2A and 2B PM Peak Sensitivity Analysis
Alternative
(Figure Description)
Intersection Operations*
Network
Delay
Airport Road SSAM
Conflicts
(Total/Crossing) US 93 Basecamp
Drive
Airport
Road S
Ramps
Airport
Road N
Ramps
Alt 2A (SE Loop RAB) B (D) C (F) A (A) A (B) 29.4 s 7 / 0
Alt 2B (SE Loop TS) B (D) C (F) A (A) C (D) 34.8 s 34 / 4
*Operations are reported as the intersection and (worst approach).
Traffic and Safety Analysis Summary
The traffic and safety analysis showed high benefits for both traffic operations and safety for all
alternatives considered. Table 8 (same as Table 1) summarizes that the alternative that provided the best
safety and second-best operations improvements for the study intersections was Alternative 2A:
Interchange with Southeast Loop Ramp and 5-Leg Roundabout at Airport Drive and Expanded NW and SE
Quadrant Interchange at Basecamp Drive (Figures #4/#7). With both intersection improvements having a
substantial right-of-way and cost impact, the traffic and safety benefits outlined in this report should only
be part of the selection of the preferred alternatives at Airport Road and Basecamp Drive.
Table 8 - Traffic Operations and Safety Rankings
Alternative
(Figure #)
Airport Road
Description
Avg Delay
Rank
VMT
Rank
Airport Road
Safety Rank
Basecamp Drive
Safety Rank
No Build 7 1 7 7
Alt 1A (Figures #1/#9) RABs 5-leg 1 6 5 5
Alt 1B (Figures #2/#9) RABs 4-leg 2 5 4 6
Alt 2A (Figures #4/#7) SE Loop RAB 2 3 1 2
Alt 2B (Figures #3/#7) SE Loop TS 6 2 3 2
Alt 3 (Figures #5/#8) SW Loop TS 5 7 2 1
Alt 4 (Figures #2/#6) RABs 4-leg 4 4 5 4
Attachment A
Attachment A:
Detailed Existing and 2045 No Build Results
Attachment B
Attachment B:
Detailed 2045 Alternative Results