Antelope Drive Extension Traffic Analysis
Introduction
The purpose of this report is to document traffic analysis of the proposed extension of Antelope
Drive to U. S. Highway 89 in Davis County. InterPlan, a Traffic Planning Consultant firm,
performed traffic analysis for a.m. and p.m. peak hours for day of opening conditions and 2040
forecast conditions. Analysis indicates that completion of the project will lead to a 34 percent
increase in traffic volumes on Antelope Drive beyond the increase expected from consolidating
the surrounding access points. Nevertheless, analysis also indicates the new Antelope
Drive/U.S. 89 intersection will function adequately during a.m. and p.m. peak hours.
Project Description
The project consists of extending Antelope Drive beyond its current terminus in Layton City to
connect with U.S. 89 at a "High‐T" signalized intersection. The High‐T intersection will allow for
unimpeded flow for northbound through vehicles and will also incorporate a channelized,
freeright‐turn lane and a corresponding merge/acceleration lane for right‐turns onto
southbound U.S. 89. In addition to the new intersection, a two‐way frontage road will be
completed on the west side of U.S. 89 between Hobbs Creek Drive and Country Oaks Drive. All
six west‐side access points in this area, including the existing signalized intersection at Sunset
Drive, will be consolidated at the new Antelope Drive/U.S. 89 intersection. Additionally the
access on the east side of U.S. 89 at 2200 North will also be closed due to its proximity to the
Antelope Drive/U.S. 89 intersection. The Frontage Road will intersect with Antelope Drive
approximately 300 feet west of U.S. 89. This intersection will feature stop‐controlled
approaches on the Frontage Road and free‐flow movements on Antelope Drive. Finally, a Utah
Transit Authority (UTA) operated park and ride lot is planned for the north side of Antelope
Drive between the Frontage Road and U.S. 89. Access to the park and ride lot will be made via
the Frontage Road.
Please note that US-89; Antelope Drive Intersection Improvements project is not the full build out of US89, but rather an interim project.
A UDOT Project
Figure 1 ‐ Antelope Drive Study Area and Proposed Changes InterPlan Co
2
Figure 2 ‐ Preliminary Roadway Layout Concept Figure 3 ‐ Project Concept Lane Configuration InterPlan Co
3
Existing Conditions InterPlan examined project area existing conditions through data collection, site analysis, and area evaluation. Roadway Network Antelope Drive Antelope Drive is a significant east/west route in the area connecting residential developments to Interstate 15 (I‐15) and the commercial sectors of Layton and Clearfield. Near I‐15, four miles to the west, Antelope Drive features a 76 foot pavement width and a five‐lane cross section. Beginning east of Hill Field Road, however, Antelope Drive narrows to a 60 foot pavement width and a three‐lane cross section with striped shoulders. East of Fairfield Road, striped bike lanes are added to either shoulder. This cross‐section effectively continues until Antelope Drive terminates at undeveloped property just 1/4 mile west of U.S. 89. (The last 1,000 feet of Antelope Drive maintains the 60 foot pavement width but features no lane striping at all.) U.S. 89 U.S. 89 is a major north/south arterial in Davis County, linking I‐15 to Interstate 84 (I‐84). The traffic composition on U.S. 89 consists of a significant portion of commuter traffic and freight traffic. Portions of U.S. 89 (to the north near I‐84 and to the south near I‐15) are access controlled, with only grade‐separated interchanges being allowed. Within the project area, U.S. 89 features two travel lanes in each direction and a two‐way left‐turn lane. Shoulders are generally 10 to 12 feet in pavement width and are frequently used by cyclists. The speed limit is 55 miles per hour (mph). U.S. 89 Access/Area Connectivity In the vicinity of the project area, access to U.S. 89 is distributed among a number of residential streets. Some streets are dead‐end streets serving fewer than a dozen homes. Others, such as Sunset Drive, are major residential roadways. Sunset Drive maintains the only signalized access on U.S. 89 in the project area via a High‐T intersection with access to and from only the west side of U.S. 89. Connectivity among the residential areas west of U.S. 89 is poor due to terrain and the meandering layout of residential roadways. In order to reach Sunset Drive (the only signalized access to U.S. 89) many drivers must cut through several neighborhood streets. Access on the east side of U.S. 89 is less frequent with residential streets connecting at Hobbs Creek Drive, 2200 North, and 2030 North. There is currently no signalized access for the east side of U.S. 89 in the project area. Data Collection InterPlan conducted a.m. and p.m. peak period traffic counts on Wednesday, June 19 and Thursday, June 20, 2013. Traffic counts captured peak hour turning movement volumes at the six existing access points on U.S. 89 between Hobbs Creek Drive and Country Oaks Drive. Figure 4 displays the a.m. and p.m. peak hour turning movement volumes. InterPlan Co
4
Figure 4 ‐ AM and PM Peak Hour Turning Movement Volumes Safety Crash data from the Utah Department of Transportation (UDOT) Traffic & Safety Division demonstrate the historic crash patterns in the study area. Figure 5 illustrates the crash types and frequencies for the most recent three years of data (2009 to 2011) in a 3D stacked bar format. The higher the bar, the more crashes that occurred at a particular location. As can be seen from Figure 5, crashes are infrequent along the U.S. 89 corridor, although a few crash clusters appear near access points for Hobbs Creek Drive, Sunset Drive, and Skyview Drive. Single vehicle crashes (noted as "Not Applicable" crashes in Figure 5), angle crashes, and front InterPlan Co
5
to rear crashes are some of the common crash types at these locations. Interestingly, in addition to angle and front to rear crashes, the Sunset Drive/U.S. 89 intersection manifests multiple sideswipe same direction crashes. These crashes are likely related to the merging movements required by the existing High‐T intersection. Figure 5 ‐ Crashes within the Study Area Table 1 summarizes crashes by manner of collision along U.S. 89 in the study area. Table 1 shows that from 2009‐2011 single vehicle crashes account for one‐third (36 percent) of all crashes in the study area. Further examination of the data revealed that about half of the single‐vehicle crashes in the project area are the result of encounters with a wild animal. The most frequent crash types involving multiple vehicles are angle and front‐to‐rear crashes, each at 23 percent. Table 2 summarizes crash severity for U.S. 89 crashes in the study area. During the analysis period, there were no severe injury or fatal crashes. Most crashes (71 percent) resulted in no injury, 16 percent of crashes resulted in a possible injury, and the remaining 13 percent resulted in non‐incapacitating injuries. Table 3 summarizes the average crash rate in the project area. Crash rates contained in this table are annual rates per million vehicle miles traveled. For this section of road there were 0.93 crashes annually per million vehicle miles. This is significantly lower than the statewide crash rate of 4.23 annual crashes per million vehicle miles on roadway of similar functional class and volume. InterPlan Co
6
Table 1 ‐ 2009‐2011 Crashes by Manner of Collision on U.S. 89, Milepost 402.87‐403.87 Manner of Collision
Number
Percentage
7 7 1 5 11 31 23%
23%
3%
16%
36%
Angle Front‐to‐rear Head‐on Sideswipe (same direction) Single Vehicle Total Source: UDOT Traffic & Safety Division Table 2 ‐ 2009‐2011 Crashes by Severity on U.S. 89, Milepost 402.87‐403.87 Crash Severity Number Percentage 22
5
4
0
0
31
71%
16%
13%
0%
0%
No Injury Possible Injury Non‐incapacitating Injury Incapacitating (Severe) Injury Fatal Total Source: UDOT Traffic & Safety Division Table 3 ‐ 209‐2011 Crash Rate on U.S. 89, Milepost 402.87‐403.87 2009‐2011 Route Begin MP End MP Crashes AADT Crash Rate1
89 402.87 403.87 31 30,110
0.93
Statewide Average Crash Rate2
4.23
1. Crashes per year per million vehicle miles. 2. From UDOT Average Crash Summary 2007‐2011 Source: UDOT Traffic & Safety Division In general, there are no significant safety issues in the project area that require special consideration. Crashes in the study area are infrequent and not severe. From 2009‐2011 there were no fatalities or severe injuries on this portion of U.S. 89 and adjacent roadways. When compared to other urban principle arterials of similar volume, the crash rate on U.S. 89 within the study area is well below average. The crash location and type are typical for the types of traffic movements that occur in the project area. Existing With Project InterPlan analyzed proposed project impacts for a "day‐of‐opening" scenario. To re‐state, this project’s proposed changes are: 1. Extend Antelope Drive to connect with U.S. 89 at a "High‐T" signalized intersection, 2. Provide a channelized, free right‐turn lane with accompanying merge/acceleration lane for right‐turn movements onto southbound U.S. 89, 3. Construct a two‐way frontage road on the west side of U.S. 89 between Hobbs Creek Drive and Country Oaks Drive, InterPlan Co
7
4. Close six west‐side accesses including existing signalized intersection at Sunset Drive, 5. Implement stop‐controlled approaches on the Frontage Road and free‐flow movements on Antelope Drive at the new Frontage Road\Antelope Drive intersection. 6. UTA will operate a park and ride lot on the north side of Antelope Drive between the Frontage Road and U.S. 89. Travel Demand Modeling Traffic conditions for the project were forecasted using the Wasatch Front Regional Council–
Mountainland Association of Governments (WFRC‐MAG) regional travel demand model version 7.0. The model base year was 2009 with future conditions forecast through 2040. Base Year Model Calibration InterPlan revised the base 2009 WFRC‐MAG model network to more accurately reflect existing conditions for the study area. Changes included modifications to roadway functional type (FT) and relocating/creating new roadway links. The changes are documented in Tables 4 and 5. First, the current base model network represents U.S. 89 as a divided, multi‐lane highway (FT 11) through the study area. U.S. 89 was changed to a principal arterial (FT 2). This change resulted in traffic volumes on U.S. 89 that most closely reflected the 2009 volumes in UDOT’s Traffic on Utah Highways(ToUH) counts data. Second, Antelope Drive between Fort Lane and Oak Forest Drive was changed from a minor arterial (FT 3) to a major collector (FT 4). Finally, since Antelope Drive does not currently connect to U.S. 89, the section of Antelope Drive between Oak Forest Drive and U.S. 89 was modified to bend to the north and connect to U.S. 89 near the existing location of the Sunset Drive/U.S. 89 intersection. This roadway link was coded as a minor collector (FT 5). These changes to Antelope Drive resulted in a configuration that better represents the residential nature of the existing network and produced traffic volumes that more closely reflect volumes derived from traffic counts. Figure 6 shows the root mean square error for the WFRC‐MAG base model network and the InterPlan‐revised model network (Antelope Drive base model) as compared to ToUH data for the study area. Based on several roads around the study area, the modified model consistently had less error than the base model, indicating that the geometric and functional type changes to the model network improved the overall accuracy of the regional model for sub‐area analysis. Table 4 ‐ Base Year Model Calibration ‐ Functional Type Changes Road U.S. 89 From SR‐273 Antelope Drive Antelope Drive Fort Lane InterPlan Co
Oak Forest Drive To I‐84 Oak Forest Drive U.S. 89 Revised FT FT 2 (Principle Arterial)
Original FT
FT 11 (High speed Multilane Highway)
FT 3 (Minor Arterial)
FT 4 (Major Collector) FT 3 (Minor Arterial)
FT 5 (Minor Collector)
8
Table 5 – Base Year Model Calibration ‐ Geometric Changes Road Antelope Drive From Oak Forest Drive To U.S. 89 Description
Realigned roadway to the north to connect to U.S. 89 at the existing location of the Sunset Drive/U.S. 89 intersection.
Figure 6 ‐ Root Mean Square Model Error 140%
120%
100%
80%
60%
40%
20%
0%
WFRC‐MAG Base Model
Antelope Drive Base Model
Project Build Model Network The project build model adopted most of the FT changes to U.S. 89 and Antelope Drive used for the base year model calibration. However, because the proposed project will connect Antelope Drive directly to U.S. 89, the build model restored the original WFRC‐MAG alignment for Antelope Drive. In other words, the Antelope Drive segment east of Oak Forest Drive was returned to its original model geometry where it connects directly to U.S. 89. Additionally, this section of Antelope Drive was changed to a major collector (FT 4) to reflect the anticipated function of the new road segment and to be consistent with the adjacent sections of Antelope Drive. Traffic Volume/Pattern Changes Table 6 compares existing and project build scenario daily traffic volumes. Model results predict that Antelope Drive will experience a 34 percent increase in daily traffic volumes when extended to U.S. 89. These results reflect the increased attractiveness of Antelope Drive when it provides a direct connection to U.S. 89. Despite increases to Antelope Drive, only minimal changes to traffic volume are predicted for U.S. 89, likely due to the subtle re‐balancing of traffic patterns in the area. InterPlan Co
9
Table 6‐ Existing and Project Build Daily Traffic Volumes Road U.S. 89 U.S. 89 Antelope Drive 1
From SR‐109 Antelope Drive Oak Forest Drive To Antelope Drive
SR‐193
U.S. 89
Existing 30,620
29,690
6,3401
Existing Project Build 30,700 30,300 8,500 Percent Change
< 1%
2%
34%
Aggregate volume from all study area existing access points. Traffic Analysis In order to conduct intersection‐specific traffic analysis, InterPlan generated peak hour intersection turning movement volumes for the project build scenario. InterPlan considered several factors in producing these estimates, including • the travel pattern changes resulting from consolidating the six existing accesses at Antelope Drive, • trip distribution through existing neighborhood connectivity and road layout, • induced traffic from connecting Antelope Drive directly to U.S. 89 as indicated by the travel demand model (34 percent increase), and • traffic patterns from access to and from the UTA‐operated park and ride lot. The travel paths to access the Antelope Drive/U.S. 89 intersection are influenced by the trip origins/destinations and the local street network. InterPlan considered the connectivity of the local street network in determining the distribution of drivers who would use Antelope Drive directly versus the Frontage Road to get to and from U.S. 89. Additionally, the model‐predicted 34 percent increase in traffic volumes due to extending Antelope Drive were included. Finally, InterPlan incorporated the increased volumes and turning movement adjustments in travel patterns due to the park and ride lot. InterPlan consulted with UTA regarding planned park and ride lot usage patterns and assumptions. Figure 7 summarizes the project build turning movement volumes at the proposed Antelope Drive/U.S. 89 intersection and the Antelope Drive/Frontage Road intersection. Intersection Level of Service (LOS) Analysis InterPlan evaluated project build intersection Level of Service (LOS) using the traffic analysis program Synchro/SimTraffic 8. Synchro provides intersection LOS outputs similar to Highway Capacity Manual 2010 (HCM) methodologies. Intersection LOS is reported on an A to F scale reflecting the average vehicle delay (seconds) at the intersection. LOS A represents the best operating conditions and LOS F the worst. Generally, LOS D is accepted as the minimally acceptable standard for peak hours in urban areas. Table 7 shows the HCM LOS criteria for signalized and unsignalized intersections. For signalized intersections, LOS is measured for the intersection as a whole whereas for unsignalized intersections, LOS is measured for the worst stop‐controlled approach. Table 8 summarizes the results of the intersection LOS analysis. As seen in Table 8 both intersections operate at an acceptable LOS for both the a.m. and p.m. peak hours. The intersections have sufficient capacity to accommodate project build traffic demand. InterPlan Co
10
Figure 7 ‐ Project Build Turning Movement Volumes Table 7 – HCM LOS Criteria Level of Service A B C D E F Average Control Delay (sec/veh)
Signalized Unsignalized Intersections Intersections 0 ‐ 10 0 ‐ 10
> 10 ‐ 20 > 10 ‐ 15
> 20 ‐ 35 > 15 ‐ 25
> 35 ‐ 55 > 25 ‐ 35
> 55 ‐ 80 > 35 ‐ 50
> 80 > 50
Source: HCM 2010 InterPlan Co
11
Table 8 – Project Build Scenario Intersection LOS Results AM Peak Hour
Intersection Antelope Drive/ U.S. 89 (signalized) Antelope Drive/ Frontage Road (stop‐controlled) PM Peak Hour
LOS
Delay 20
Worst Approach
N/A
C
21 Worst Approach
N/A
13 Southbound
C
19 Southbound
LOS
Delay
B/C
B
Queuing Analysis Vehicle queuing can influence traffic flow in ways not captured by simple intersection LOS analysis. Specifically, the close spacing between U.S. 89 and the Frontage Road has the potential to lead to queue spillback between intersections on Antelope Drive. If queues from the U.S. 89 intersection were to spill back into the Frontage Road intersection, or vice versa, it could create operational and safety concerns and even lead to gridlock. As currently designed there is only approximately 200 to 250 feet of queue storage available between intersections. To examine vehicle queuing conditions, InterPlan imported the Synchro traffic network into the SimTraffic microsimulation analysis program and measured output 95th percentile queue lengths. Due to the randomness inherent with microsimulation analysis, InterPlan averaged the results over multiple simulation runs. Early design concepts for the proposed project did not include the free‐right turn onto southbound U.S. 89. As such, it was determined that right‐turning vehicles would back into the Antelope Drive/Frontage Road intersection during the a.m. peak hour. Consequently, the free‐
right turn lane was added to the concept design to allow drivers to complete a right turn, without stopping, at any point in the signal cycle. Thus, the queuing problem was successfully mitigated. Table 9 documents the results of the queuing analysis. Table 9 – Project Build Scenario Queuing Results at Antelope Drive/U.S. 89 95th Percentile Queue Length (ft)
Intersection Eastbound RT at U.S. 89 Eastbound LT at U.S. 89 AM Peak Hour (w/o free Right Turn) (w/ free Right Turn) 250
175 175
175 PM Peak Hour 75 200 Safety As mentioned previously, the proposed project will consolidate six accesses into a single, signalized access point on U.S. 89. By reducing the number of conflict points, it is anticipated that crashes (particularly angle crashes) will decrease on U.S. 89. Because the proposed design of the new Antelope Drive intersection will be similar to the existing High‐T signal at Sunset Drive, crash patterns are expected to be comparable to what is currently experienced at Sunset Drive. Specifically, there may be some occurrence of sideswipe crashes at the new intersection related to the merging activity of a High‐T intersection. InterPlan Co
12
Future Conditions InterPlan investigated future conditions to account for the long‐term impacts of the proposed project and to investigate the lifespan of the project improvements in the context of planned changes to the background transportation network. Future Surrounding Area Projects Future WFRC Long Range Transportation Plan projects have a significant influence on traffic patterns in the study area. Several projects directly impact Antelope Drive, U.S. 89, and U.S. 89 intersections. While these projects are planned out over the next thirty years, the cumulative effect is to convert U.S. 89 into a six‐lane freeway‐type facility with grade separated interchanges at every access point. Table 10 summarizes these projects and includes the planned timeframe for implementation: Phase 1 (2011‐2020), Phase 2 (2021‐2030), Phase 3 (2031‐2040). It should be noted that while the long range transportation plan denotes a Phase 1 project to construct an interchange at Antelope Drive/U.S. 89, the scope of the current project is to construct an at‐grade intersection and frontage road only. It is unknown when the full plan to create an interchange at Antelope Drive will be realized. Table 10 – WFRC Planned Projects Affecting U.S. 89 Phase
1 1 2 2 2 3 Road U.S. 89 U.S. 89 U.S. 89 U.S. 89 U.S. 89 U.S. 89 Location
Antelope Drive 400 North (Fruit Heights)
From I‐84 to Antelope Drive
Gordon Avenue SR‐109 (Oak Hills Drive)
Antelope Drive to I‐15
Improvement Type Construct interchange1
Construct interchange
Widening, Upgrade Antelope to interchange
Construct interchange
Construct interchange
Widening
1. Construction of a grade‐separated interchange is not within the scope of the current project. Future Travel Demand Modeling Future travel demand model scenarios were performed for the 2040 forecast year. InterPlan prepared two 2040 analysis scenarios. The first scenario incorporated all WFRC‐MAG 2040 Long Range Transportation Plan projects. The second scenario adopted all future projects except for planned improvements to U.S. 89 in the vicinity of the study area. The purpose of running the second scenario was to fully test the lifespan for the proposed project, since long‐term plans for U.S. 89 would eventually supersede the shorter‐term improvements evaluated in this study. Specifically, converting the Antelope Drive/U.S. 89 intersection to a grade‐separated interchange would require a full reconstruction of the High‐T intersection and the adjacent frontage road. Essentially, the second scenario helps InterPlan to determine if the proposed project will continue to function adequately up to 2040 as if it were the only improvement to the highway. Table 11 summarizes the model network differences between each scenario. InterPlan Co
13
Table 11 – Comparison of 2040 Model Networks Road From To 2040 Long Range Plan (Calibrated)
2040 No U.S. 89 Projects
U.S. 89 SR‐273 Antelope Drive U.S. 89 Fort Lane U.S. 89 U.S. 89 U.S. 89 U.S. 89 I‐84 Antelope Drive Interchange Gordon Avenue Interchange Oak Hills Drive Interchange 200 North Interchange FT 2 (Principle Arterial) FT 31 (Freeway: Lower Capacity)
FT 3 (Minor Arterial)
FT 4 (Major Collector) Grade‐separated Interchange
At‐grade Intersection Grade‐separated Interchange
At‐grade Intersection Grade‐separated Interchange
At‐grade Intersection Grade‐separated Interchange
At‐grade Intersection Model Results Table 12 compares the project build volumes in both 2040 model scenarios. Without the conversion of U.S. 89 to a freeway‐type facility, traffic volumes on study area roadways remain relatively stable, only increasing by approximately one percent. However, if U.S. 89 is upgraded to reflect changes in the WFRC‐MAG Long Range Transportation Plan, the volumes on U.S. 89 dramatically increase by approximately 125 to 130 percent. Corresponding volumes on Antelope Drive increase by 22 percent. The current project, however, is not required to accommodate the predicted freeway‐level volumes since any freeway conversion would result in a full reconstruction of the High‐T intersection and the adjacent frontage road. Table 12‐ Future Model Daily Traffic Volumes Road U.S. 89 U.S. 89 From SR‐109 To Existing Project Build Antelope Drive SR‐193 Antelope Drive Antelope Oak Forest U.S. 89 Drive Drive 2040 Percent With U.S. 89 Change LRTP Projects Percent Change 30,700
2040
Without U.S. 89 LRTP Projects
31,100
1%
69,200 125%
30,300
30,700
1%
69,700 130%
8,500
8,600
1%
10,400 22%
Traffic Analysis To conduct detailed traffic analysis, InterPlan developed future peak hour turning movement volumes for study area intersections based on no additional Long Range Transportation Plan projects to U.S. 89. As mentioned previously, without future improvements, traffic volume growth for surrounding roadways is expected to be remain low. Thus in order to produce a conservative (high) estimate of future travel demand, InterPlan generated future turning movement volumes by applying a 0.5 percent annual growth rate to existing turning movement InterPlan Co
14
volumes. This effort resulted in volumes slightly higher than those that would be generated by considering model‐predicted growth alone. Figure 8 displays the resulting peak hour turning movement volumes. Figure 8 ‐ 2040 Project Build Turning Movement Volumes Intersection Level of Service (LOS) Analysis InterPlan evaluated project build intersection LOS for 2040 conditions. Table 13 summarizes the results of the analysis. As seen in Table 13 both intersections operate at an acceptable LOS for both the a.m. and p.m. peak hours. The intersections have sufficient capacity to accommodate future traffic demand and project build demand. InterPlan Co
15
Queuing Analysis InterPlan investigated queuing performance of the future project build scenario. As seen in Table 14, the importance of the free right‐turn lane is again manifest during the a.m. peak hour. With the free right‐turn lane, right‐turn queues do not encroach on the Antelope Drive/Frontage Road intersection. Table 13 – 2040 Project Build Scenario Intersection LOS Results AM Peak Hour
Intersection Antelope Drive/ U.S. 89 (signalized) Antelope Drive/ Frontage Road (stop‐controlled) PM Peak Hour
LOS
Delay 28
Worst Approach
N/A
C
21 Worst Approach
N/A
14
Southbound
C/D
25 Southbound
LOS
Delay
C
B
Table 14 – 2040 Project Build Scenario Queuing Results at U.S. 89/Antelope Drive 95th Percentile Queue Length (ft)
Intersection Eastbound RT at U.S. 89 Eastbound LT at U.S. 89 AM Peak Hour (w/o free Right Turn) (w/ free Right Turn) 300
200 175
175 PM Peak Hour 125 200 Conclusions Traffic analysis shows that the proposed extension of Antelope Drive to U.S. 89 and the consolidation of access points on U.S. 89 is an acceptable improvement. The design can serve the combined U.S. 89 traffic demand from the six existing accesses between Hobbs Creek Drive and Country Oaks Drive. The design can also accommodate the expected 34 percent increase in traffic demand (as predicted by the travel demand model) resulting from streamlining access to U.S. 89 and improving east‐west connectivity on Antelope Drive. Finally, the design is expected to operate properly with the current configuration of U.S. 89 up to 2040. Substantial traffic growth is expected if the Long Range Transportation Plan is fully realized and U.S. 89 is converted into a freeway‐type facility. However, the proposed project is not designed to serve such demand because, at that point, the intersection would be reconstructed as a grade‐
separated interchange. Historical crash data indicates crash occurrences in the study area are low compared to urban roadways of similar functional class and traffic volume. Likewise there have been no fatal or severe injury crashes in the most recent three years of data. The proposed project is expected to result in some crash reduction due to the consolidation of access points into a single, signalized access on U.S. 89. Crash patterns at the new Antelope Drive/U.S. 89 High‐T intersection are anticipated to be similar to those experienced at the existing High‐T intersection at Sunset Drive. InterPlan Co
16