CLIMBING AND PASSING LANE

PRIORITIZATION STUDY

Executive Summary

February 2015

TABLE OF CONTENTS
1. PROJECT OVERVIEW ........................................................................................................................... 1
Purpose and Need .................................................................................................................... 2
Project Charter.......................................................................................................................... 3
Technical Advisory Committee .................................................................................................... 3
Agency/Stakeholder Coordination .............................................................................................. 4
ADOT Partnering Process ........................................................................................................... 4
Study Process ............................................................................................................................ 4
Passing/Climbing Lanes - Strategic Highway Safety Plan (SHSP) .................................................... 5

2. IDENTIFICATION AND PRIORITIZATION ............................................................................................... 6
Existing Conditions .................................................................................................................... 6
Passing Lanes on Two-Lane Highways ......................................................................................... 7
Climbing Lanes on Two-Lane Highways ..................................................................................... 13
Climbing Lanes on Multilane Highways ..................................................................................... 17

i

LIST OF FIGURES
1.1: Study Process .......................................................................................................................... 4
2.1: Identification Process for Passing Lanes on Two-Lane Highways ................................................... 7
2.2: Prioritization Process for Passing Lanes on Two-Lane Highways .................................................... 8
2.3: Statewide Ranking of Passing Lanes......................................................................................... 12
2.4: Identification Process for Climbing Lanes on Two-Lane Highways ............................................... 13
2.5: Statewide Climbing Lane (Two-Lane Highways) Rankings .......................................................... 16
2.6: Identification Process for Climbing Lanes on Multilane Highways ............................................... 17
2.7: Prioritization Process for Climbing Lanes on Multilane Highways ................................................ 18
2.8: Statewide Ranking of Climbing Lanes on Multilane Highways .................................................... 20

LIST OF TABLES
2.1: Passing and Climbing Lanes by ADOT Districts .......................................................................... 6
2.2: Prioritization Criteria for Passing Lanes on Two-Lane Highways .................................................... 8
2.3: Prioritized List of Passing Lanes on Two-Lane Highways ............................................................... 9
2.4: Prioritized List of Climbing Lanes on Two-Lane Highways ........................................................... 14
2.5: Prioritization Criteria for Climbing Lanes on Multilane Highways ................................................ 18
2.6: Prioritized List of Climbing Lanes on Multilane Highways ........................................................... 19

ii

1. PROJECT OVERVIEW
In 1999, the Arizona Department of Transportation (ADOT) commissioned a study to:


Establish a process to identify locations where a passing or climbing lane would provide benefit to
the traveling public; and



Rank the identified passing and climbing lanes locations by the most effective and feasible projects.

The end result of that study was a prioritized list of general locations for passing and climbing lanes within
Arizona. In 2003, the study was updated to refine the previous methodology and to identify and reprioritize
passing and climbing lane locations. Since this study was completed there has been a significant change in
traffic patterns on the Arizona State Highway System that warranted the need to develop an updated list of
passing and climbing lane candidate locations. The purpose of this study is to further enhance the 2003
methodology and to develop a new priority list of locations for passing and climbing lanes utilizing ADOT's
more robust and current transportation datasets.
For the purpose of this study, passing and climbing lanes are defined as:
Passing Lane - Additional lane on highways to facilitate the passing of all types of slow

moving vehicles at locations other than sustained grades where passing
opportunities are unavailable or very limited over a long stretch of
highway.
Climbing Lane - Additional lane on steep upgrades to facilitate the passing of trucks and

slow moving vehicles whose speed drops because of the sustained grade
rather than a lack of passing opportunity over a long stretch of highway.
Key benefits of incorporating passing and climbing lanes on highways include:




Reduced delays at specific bottleneck locations, such as steep upgrades where slow-moving vehicles
are present;
Improved overall traffic operations by breaking up traffic platoons and reducing delays caused by
inadequate passing opportunities over substantial lengths of highway; and
Improved safety by reducing the need for passing vehicles to travel in the opposing lane.

While passing and climbing lanes are physically identical, they serve two different purposes. Usually passing
lanes are used on two-lane highways, while climbing lanes are utilized on extended upgrade locations on
two-lane and multilane highways.




For two-lane highways with moderate to high traffic volume levels, lack of passing opportunities at
regular intervals often results in long queues and poor performance. In lieu of costly widening
projects, adding a passing lane at these locations alleviates the problem.
For two-lane highways with extended upgrade locations, trucks and other slow moving vehicles
experience significant drop in speed causing long queues and poor performance even with low
traffic volume levels. Adding a climbing lane at these locations alleviates the problem and

1



significantly enhances safety by reducing the need for passing vehicles to maneuver into the
opposing lane.
For multilane highways, "no passing" zones are not an issue. However, a highway with extended
upgrade locations and high truck traffic causes the trucks to experience a significant drop in speed
results in excessive queuing and unsafe conditions. Adding a climbing lane at these locations
alleviates the problem.

For these reasons, this study identified, evaluated, and prioritized passing and climbing lanes for the
following scenarios:




Passing lanes on two-lane highways
Climbing lanes on two-lane highways
Climbing lanes on multilane highways

PURPOSE AND NEED
With the ultimate purpose of enhancing safety and improving mobility, the Climbing and Passing Lane
Prioritization Study was initiated to develop a prioritized list of candidate locations for climbing and passing
lanes. The need for this study stems directly from ADOT’s desire to increase safety and mobility along the
Arizona State Highway System. The project purpose is demonstrated with the following statement of need:






Update the Methodology. The previous study and methodology has not been updated since 2003.
ADOT now has more accurate data and several newer datasets which could be utilized to enhance
the previous methodology to produce better recommendations.
Update the List of Passing/Climbing Lane Locations. Since the last update, there has been a
significant change in traffic patterns on the Arizona State Highway System that warranted the need to
develop an updated list of passing and climbing lane candidate locations. In addition, several of the
recommendations from the previous study have since been implemented and the list has to be
updated.
Address Safety and Improve Mobility. Adding a passing/climbing lane along an existing highway is
one of the most cost effective ways to enhance safety and improve mobility. New passing/climbing
lane locations would provide a tremendous benefit to the traveling public.

2

PROJECT CHARTER
At the first Technical Advisory Committee (TAC) meeting, a Project Charter was developed with assistance
from members of the TAC. As part of the Project Charter, a Mission Statement and Goals were developed
to provide guidance to the study team.

Mission Statement
Develop a needs based prioritization for Climbing and Passing Lane locations on the Arizona State Highway
System

Study Goals
Quality - Enhance safety and improve mobility; when typical design standards can’t be met, reference the
2010 Highway Safety Manual for additional guidance; work towards objective and needs based
prioritization for climbing and passing lanes; consider best practices from other states

Communication - Create a website to house climbing and passing lane study documents; reach every team
member and/or intended recipient when communicating

Issue Resolution - Be proactive with resolving issues; understand the process for how this team moves issues
forward and resolve issues timely; discuss at TAC meetings as necessary to communicate decisions to all
team members

Teamwork - Interrelationships understood; work together to meet the challenge; take ownership of the study
Schedule - Keep and attend scheduled meetings; meet the delivery dates for the prioritization
Budget - Identify projects that can realistically be programmed; sensitivity to the route and route continuity
(best bang for the dollar); communicate the need for specified funding for climbing/passing lanes

Project Delivery - Reach consensus on how to prioritize; include functional class factor when setting
priorities; prepare a needs based prioritization that is defendable and can be reviewed annually – the end
result is the list

TECHNICAL ADVISORY COMMITTEE
The study is guided by a Technical Advisory Committee (TAC). The role of the TAC is to provide technical
guidance, support, advice, suggestions, recommendations, and to perform document reviews throughout
the study process. TAC members included representatives from:
ADOT Statewide Project Management

ADOT State Engineer’s Office

ADOT Engineering Districts

ADOT Communications Division

ADOT Multimodal Planning

Federal Highway Administration

ADOT Traffic Design/Safety
ADOT Partnering Section
ADOT Roadway Design

3

AGENCY/STAKEHOLDER COORDINATION
To develop a thorough understanding of the issues, deficiencies, and needs, the study team identified a core
group of stakeholders and conducted two rounds of interviews. The stakeholders included representatives
from each ADOT District office. The study team also sent out email notifications to each Council of
Governments (COGs) and Metropolitan Planning Organizations (MPOs) to request feedback. Stakeholders’
feedback summary is presented in later chapters of this document.

ADOT PARTNERING PROCESS
The Climbing and Passing Lane Prioritization Study was conducted as per the guidelines of ADOT’s
Partnering Process. Partnering is a process of collaborative teamwork to achieve measurable results through
agreements and productive working relationships. The Partnering Principles include Communication,
Commitment, Cooperation, and Continuous Improvement, and assist project teams to jointly solve
problems, increase work efficiency, improve the project delivery process, and build and strengthen
relationships. Project teams that agree on measurable goals, and utilize the partnering principles are more
successful, and meet or exceed budget and schedule goals. In short, Partnering is a formal way for groups
to work together and resolve issues.
The ADOT Partnering Office assisted with facilitating the creation of the collaborative partnership
agreement. In addition, the Partnering facilitator assisted with setting up the measurement tool, Partnering
Evaluation Program, or PEP. At the end of each TAC meeting, members were requested to complete and
submit the PEP forms.

STUDY PROCESS
An eight step comprehensive process was used to complete this study. The study team maintained contact
with TAC and stakeholders by meeting at regular intervals through the course of the study. Figure 1.1
illustrates the process utilized for this study.

Figure 1.1: Study Process

4

PASSING/CLIMBING LANES - STRATEGIC HIGHWAY SAFETY PLAN (SHSP)
ADOT recently adopted a Statewide SHSP; that is intended to be a “living” implementation document,
coordinating the efforts of individual Emphasis Areas to the overall goals and objectives of the SHSP. The
2014 Arizona SHSP is a data-driven, strategic approach to reduce fatalities and serious injuries on state
roads. The 2014 SHSP update defines 12 Emphasis Areas focused on improving specific areas of roadway
safety. During the SHSP update process, the roadway infrastructure improvements were identified as an
effective countermeasure.

SHSP Section 14: Roadway Infrastructure and Operations | Lane / Roadway Departure
This emphasis area addresses head-on crashes associated with highway segments. A head-on crash
typically occurs when a vehicle crosses a centerline or a median and collides with an approaching vehicle,
or when a driver travels the wrong way in a traffic lane. Head-on crashes are often a result of a driver’s
inadvertent actions, such as running off the road, or deliberate actions, such as performing unsafe passing
maneuvers.

SHSP Section 14 – Goals and Objectives
The Emphasis Area goal for SHSP Section 14 is to, “reduce fatalities and the occurrence of serious injuries
on all public roadways in Arizona through enhance roadway infrastructure and operations.” The objectives
for reducing the number of head-on fatal crashes are:




Keep vehicles from encroaching into the opposite lane,
Minimize the likelihood of a car crashing into an oncoming vehicle, and
Reduce the severity of crashes that occur.

Effectiveness of Strategies and Proposed Action
The construction of passing and climbing lanes is a strategy that supports the SHSP Section 14 goals and
objectives. A variety of studies conducted over the last twenty years have shown that the addition of passing
and climbing lanes on highways reduces accident rates. Jacobs validated the safety benefit of adding
passing and climbing lanes by conducting a crash analysis of selected location on both two-lane and multilane highways. The results of this analysis are documented on page 28 and 29 of this document.

5

2. IDENTIFICATION AND PRIORITIZATION
EXISTING CONDITIONS
Compiling a comprehensive inventory of existing passing/climbing lane locations is an essential first step
before evaluating the need for new passing/climbing lanes. ADOT’s existing passing and climbing lanes
data set was used as the starting point. Each passing/climbing lane location and length was verified against
aerial imagery. Table 2.1 provides a summary of the number of passing and climbing lanes in each ADOT
District. Approximately 169 passing/climbing lanes currently exist on two-lane highways and the length of
the passing lanes varies from 0.25 miles to over a mile. Shorter passing lanes are typically less effective than
longer passing lanes especially on highways with higher traffic volume levels.
On multilane highways, “no passing” zones is not an issue; extended upgrade locations coupled with high
truck traffic warrant the need for climbing lanes on multilane highways. Currently, only four climbing lanes
exist on Arizona’s multilane highways however, a few are now under construction and a few more are in the
design stage.

Table 2.1: Passing and Climbing Lanes by ADOT Districts
Passing/Climbing Lanes on Two-Lane Highways
ADOT District

Flagstaff
Globe
Holbrook
Kingman
Prescott
Safford
Tucson*
Yuma
Total

Climbing Lanes
on Multilane
Highways

< 0.5 mile

0.5 - 1 mile

> 1 mile

Total

> 1 mile

1
7
2
1
21
1
0
0
33

15
23
0
8
12
5
0
5
68

16
21
10
7
6
3
0
5
68

32
51
12
16
39
9
0
10
169

2
0
0
2
0
0
0
0
4

6

PASSING LANES ON TWO-LANE HIGHWAYS
Methodology for Identification and Ranking
Figure 2.1 illustrates the steps utilized to identify potential candidate locations for passing lanes on two-lane
highways and Figure 2.2 illustrates the steps for prioritization of the candidate locations. Once a preliminary
list of potential candidates was identified, three different prioritization methods (Table 2.2) were evaluated:
 Option 1 – Subjective Rating Method: In this method, each prioritization criteria was assigned a
weight and a maximum number of points based on discussions with TAC and Districts.
 Option 2 – Z Score Method: In this method, each prioritization criteria is given the same weight.
However, the points/score are determined using a z score value that is based on each record’s
relative distance from the mean of all records. This method is based solely on technical analysis.
 Option 3 – Combined Method: This method represents a combination of subjective and technical
analysis. In this method, the z score from Option 2 is multiplied by weights used in Option 1.

Figure 2.1: Identification Process for Passing Lanes on Two-Lane Highways

7

Figure 2.2: Prioritization Process for Passing Lanes on Two-Lane Highways

Table 2.2: Prioritization Criteria for Passing Lanes on Two-Lane Highways
Criteria

Option 1: Subjective
Rating Method
Points

Mobility
Existing LOS: PTSF – Percent Time Spent Following
Existing LOS: PFFS – Percent of Free Flow Speed
Proximity to Adjacent Passing/Climbing Lanes
Future LOS: PTSF – Percent Time Spent Following
Future LOS: PFFS – Percent of Free Flow Speed
Safety
Existing Crash Rate
Existing Crash Severity (EPDO)
Existing Passing Related Crash Rate
Future Crash Severity (Future EPDO)
Construction Feasibility
Cost per Lane Mile
(Low, Med, or High - Assessed Based on Physical
Constraints)
Bridge Widening Cost
(Low, Medium, High - Assessed based on additional SQFT )
Total Points

Overall
Percent

Option 2: Z
Score Method
Z Score
(From Analysis)

Option 3: Combined
Method
Z Score
(From Analysis)

Overall
Percent

14
4
4
2
2
2
20
5
7
4
4
6

35%
10%

3

7.5%

3

7.5%

7.5%

40

100%

100%

10%
5%
5%
5%
50%
13%
18%
10%
10%
15%

In this method, each
prioritization criteria
is given the same
weight. However, the
points/score are
determined using a z
score value that is
based on each
record’s relative
distance from the
mean of all records.

35%
10%
10%
5%
5%
5%
50%
13%
18%
10%
10%
15%
7.5%

8

Recommended Prioritization
Table 2.3 presents the list of candidate locations for passing lanes on two-lane highways. The candidate
locations are ranked at the statewide and district level and grouped into three tiers – high, medium, and low
priority. Figure 2.3 illustrates the statewide location of the passing lanes. Locations identified for passing

lanes in Table 2.3 represent only the general problem area and not the exact location and length of the
passing lanes.

Table 2.3: Prioritized List of Passing Lanes on Two-Lane Highways
ADOT
DISTRICT
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Globe
Globe
Globe
Globe
Globe
Globe
Globe
Globe
Globe
Holbrook

PASSING LANE LOCATION
(VICINITY)
SR 64 EB: MP223 - MP226
SR 67 NB: MP586 - MP583
US 180 EB: MP238 - MP236
SR 64 WB: MP220 - MP213
US 160 WB: MP343 - MP337
SR 64 EB: MP195 - MP204
SR 64 WB: MP204 - MP201
US 89 NB: MP463 - MP 466
US 160 EB: MP311 - MP320
US 89 SB: MP456 - MP453
US 89 SB: MP480 - MP477
US 89 NB: MP451 - MP460
US 89 NB: MP477 - MP480
US 89 NB: MP509 - MP512
SR 64 EB: MP211 - MP218
US 160 EB: MP335 - MP341
US 89 SB: MP502 - MP499
US 89 SB: MP512 - MP509
US 60 WB: MP348 - MP345
US 60 WB: MP294 - MP296
US 60 EB: MP345 - MP348
US 60 EB: MP357 - MP360
US 70 WB: MP288 - MP281
US 70 EB: MP267 - MP270
US 70 WB: MP270 - MP267
US 60 EB: MP304 - MP307
US 60 WB: MP266 - MP263
US 191 SB: MP442 - MP451

TOTAL POINTS
25.99
23.82
23.59
23.53
23.23
23.19
21.91
21.64
21.37
19.63
19.41
17.80
17.31
16.95
16.85
16.75
16.27
13.55
26.98
26.26
25.67
24.76
21.81
21.38
21.38
19.27
15.18
25.01

STATEWIDE
RANK
14
31
33
34
36
37
47
50
53
62
63
71
77
81
83
85
89
98
6
9
15
20
48
51
51
64
95
17

DISTRICT
RANK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1
2
3
4
5
6
6
8
9
1

TIER
LEVEL
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
1
1
1
1
2
2
2
2
3
1

9

Table 2.3: Prioritized List of Passing Lanes on Two-Lane Highways (Continued)
ADOT
DISTRICT
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Kingman
Kingman
Kingman
Kingman
Kingman
Kingman
Kingman
Kingman
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott

PASSING LANE LOCATION
(VICINITY)
US 191 NB: MP448 - MP455
SR 264 EB: MP453 - MP460
US 160 WB: MP377 - MP381
US 191 SB: MP455 - MP452
SR 87 NB: MP293 - MP296
SR 87 NB: MP296 - MP293
US 160 EB: MP377 - MP383
US 160 EB: MP361 - MP367
US 160 WB: MP361 - MP367
SR 264 EB: MP376 - MP378
US 160 EB: MP385 - MP391
US 160 WB: MP458 - MP463
US 160 WB: MP369 - MP375
US 191 NB: MP422 - MP425
US 160 EB: MP369 - MP375
SR 264 EB: MP401 - MP404
SR 264 EB: MP387 - MP394
SR 264 WB: MP387 - MP394
US 93 NB: MP167 - MP165
SR 95 NB: MP194 - 201
US 93 SB: MP165 - MP172
SR 95 SB: MP166 - MP175
SR 89 NB: MP352 - MP358
SR 89 SB: MP358 - MP364
SR 95 NB: MP166 - MP173
SR 89 NB: MP360 - MP362
SR 87 SB: MP273 - MP279
SR 89 NB: MP302 - MP304
SR 89 NB: MP330 - MP334
SR 89 SB: MP330 - 335
SR 87 SB: MP264 - MP271
SR 89 SB: MP302 - 306
SR 89 NB: MP295 - MP302
SA 89 SB: MP344 - MP347
SR 89 SB: MP295 - MP302
SR 87 NB: MP262 - MP271
SR 87 NB: MP273 - MP279
SR 169 NB: MP4 - MP10
SR 87 NB: MP281 - MP287

TOTAL POINTS
24.96
23.92
21.36
20.70
18.60
18.03
17.65
17.41
17.00
16.29
16.25
15.89
15.80
15.43
14.58
13.36
12.83
12.14
24.78
23.27
23.06
23.00
18.18
17.52
17.17
16.40
30.73
30.00
28.66
28.12
26.64
26.45
26.20
26.17
25.43
24.59
24.46
24.44
24.01

STATEWIDE
RANK
18
30
54
57
68
70
73
75
80
88
90
91
92
93
96
100
101
102
19
35
38
39
69
74
78
87
1
3
4
5
7
8
11
12
16
21
23
24
28

DISTRICT
RANK
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
9
10
11
12
13

TIER
LEVEL
1
2
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
1
2
2
2
3
3
3
3
1
1
1
1
1
1
1
1
1
1
2
2
2

10

Table 2.3: Prioritized List of Passing Lanes on Two-Lane Highways (Continued)
ADOT
DISTRICT
Prescott
Prescott
Prescott
Safford
Safford
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Tucson
Yuma
Yuma
Yuma
Yuma
Yuma
Yuma
Yuma
Yuma
Yuma
Yuma

PASSING LANE LOCATION
(VICINITY)
SR 87 SB: MP258 - MP263
SR 87 SB: MP289 - MP291
SR 87 NB: MP289 - MP291
SR 80 WB: MP349 - MP346
US 191 NB: MP138 - MP145
SR 83 NB: MP43 - MP50
SR 86 EB: 161 - MP164
SR 86 WB: MP161 - MP164
SR 86 WB: MP153 - MP156
SR 77 NB: MP91 - MP94
SR 79 NB: MP93 - MP99
SR 79 SB: MP103 - MP97
SR 83 SB: MP45 - MP54
SR 287 NB: MP137 - MP140
SR 86 EB: MP153 - MP156
SR 87 SB: MP138 - MP140
SR 87 NB: MP152 - MP160
SR 87 SB: MP152 - MP160
SR 86 WB: MP85 - MP91
SR 79 NB: MP101 - MP107
SR 83 NB: MP49 - MP54
SR 287 NB: MP142 - MP139
SR 95 SB: MP95 - MP93
SR 87 NB: MP138 - MP141
SR 79 SB: MP107 - MP105
SR 86 EB: MP85 - MP91
SR 95 NB: MP158 - MP161
SR 95 NB: MP132 - MP139
SR 95 SB: MP132 - MP139
US 95 NB: MP88 - MP90
SR 95 NB: MP152 - MP155
US 95 NB: MP92 - MP98
US 95 SB: MP92 - MP98
US 95 SB: MP84 - MP90
US 95 NB: MP76 - MP82
US 95 SB: MP76 - MP82

TOTAL POINTS
23.96
19.75
17.67
22.13
20.06
30.11
26.24
26.12
24.51
24.40
24.12
24.04
23.78
22.51
22.42
22.25
22.11
21.95
20.91
20.80
20.21
20.16
19.27
18.96
17.33
15.38
22.45
21.74
18.98
17.10
16.89
16.79
16.74
14.57
13.40
12.05

STATEWIDE
RANK
29
61
72
44
60
2
10
13
22
25
26
27
32
40
42
43
45
46
55
56
58
59
65
67
76
94
41
49
66
79
82
84
86
97
99
103

DISTRICT
RANK
14
15
16
1
2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
1
2
3
4
5
6
7
8
9
10

TIER
LEVEL
2
2
3
2
2
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
2
2
2
3
3
3
3
3
3
3

Note:
Statewide Rank = Projects ranking statewide
District Rank = Projects ranking within District only
Tier Level = High, medium, and low priority

11

Figure 2.3: Statewide Ranking of Passing Lanes

12

CLIMBING LANES ON TWO-LANE HIGHWAYS
Methodology for Identification and Ranking
Figure 2.4 illustrates the steps utilized to identify potential candidate locations for climbing lanes on twolane highways. The prioritization process for climbing lanes is the same as that for passing lanes on twolane highways and illustrated in Figure 2.4. Once a preliminary list of potential candidates was identified,
similar to passing lanes, three different prioritization methods (Table 2.2) were evaluated:
 Option 1 – Subjective Rating Method: In this method, each prioritization criteria was assigned a
weight and a maximum number of points based on discussions with TAC and Districts.
 Option 2 – Z Score Method: In this method, each prioritization criteria is given the same weight.
However, the points/score are determined using a z score value that is based on each record’s
relative distance from the mean of all records. This method is based solely on technical analysis.
 Option 3 – Combined Method: This method represents a combination of subjective and technical
analysis. In this method, the z score from Option 2 is multiplied by weights used in Option 1.

Figure 2.4: Identification Process for Climbing Lanes on Two-Lane Highways

13

Recommended Prioritization
Table 2.4 presents the list of candidate locations for climbing lanes on two-lane highways. The candidate
locations are ranked at the statewide and district level and grouped into three tiers – high, medium, and low
priority. Figure 2.5 illustrates the statewide location of the climbing lanes. Locations identified for climbing

lanes in Table 2.4 represent only the general problem area and not the exact location and length of the
climbing lanes.

Table 2.4: Prioritized List of Climbing Lanes on Two-Lane Highways
ADOT
DISTRICT
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Globe
Globe
Globe
Globe
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Holbrook
Kingman
Kingman
Prescott

CLIMBING LANE LOCATION
(VICINITY)
SR 67 NB: MP591 - MP589
SR 64 SB: MP199 - MP197
US 180 WB: MP219 - MP221
SA 89 NB: MP392- MP398
SR 64 EB: MP196 - MP198
US 160 WB: MP345 - MP343
UA 89 NB: MP566 - MP571
US 89 NB: MP550 - MP552
US 160 EB: MP312 - MP314
US 89 SB: MP557 - MP555
UA 89 NB: MP550 - MP551
US 60 EB: MP306 - MP307
US 70 WB: MP282 - MP288
US 70 EB: MP262 - MP264
US 60 WB: MP267 - MP266
SR 87 NB: MP295 - MP297
SR 264 EB: MP457 - MP461
SR 87 NB: MP290 - MP296
SR 87 SB: MP290 - MP296
US 160 WB: MP462 - MP460
US 160 EB: MP381 - MP384
US 191 SB: MP356 - MP354
US 191 SB: MP444 - MP442
SR 264 EB: MP377 - MP379
SR 264 EB: MP402 - MP404
US 93 SB: MP161 - MP163
SR 95 SB: MP177 - MP175
SA 89 SB: MP339 - MP343

TOTAL
POINTS
24.25
23.44
22.96
22.93
22.66
22.65
19.97
18.44
18.13
17.29
13.67
23.02
22.00
19.06
14.20
23.38
23.19
21.38
19.81
17.25
16.65
16.52
15.58
15.46
12.66
25.03
23.53
30.73

STATEWIDE
RANK
9
11
15
16
18
19
24
30
32
33
44
14
21
28
41
12
13
22
26
34
35
36
38
39
45
8
10
1

DISTRICT
RANK
1
2
3
4
5
6
7
8
9
10
11
1
2
3
4
1
2
3
4
5
6
7
8
9
10
1
2
1

TIER
LEVEL
2
2
2
2
2
2
2
3
3
3
3
2
2
2
3
2
2
2
2
3
3
3
3
3
3
1
2
1

14

Table 2.4: Prioritized List of Climbing Lanes on Two-Lane Highways (Continued)
ADOT
DISTRICT
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Safford
Safford
Safford
Safford
Safford
Safford
Safford
Safford
Tucson
Tucson
Tucson

CLIMBING LANE LOCATION
(VICINITY)
SA 89 NB: MP334 - MP336
SR 260 EB: MP288 - MP289
SR 89 NB: MP339 - MP341
SA 89 SB: MP348 - MP349
SR 89 NB: MP344 - MP345
SR 169 SB: MP9 - MP7
UX 191 NB: MP168 - MP171
UX 191 SB: MP169 - MP167
SR 90 WB: MP329 - MP327
SR 90 EB: MP335 - MP337
US 191 NB: MP139 - MP144
SR 80 EB: MP334 - MP338
SR 80 EB: MP314 - MP317
US 191 NB: MP147 - MP149
SR 83 NB: MP43 - MP49
SR 83 SB: MP54 - MP52
SR 83 NB: MP52 - MP54

TOTAL
POINTS
27.80
25.40
22.84
19.75
14.07
13.68
28.23
26.54
25.93
22.46
20.08
18.14
15.75
15.40
30.56
19.90
19.04

STATEWIDE
RANK
4
7
17
27
42
43
3
5
6
20
23
31
37
40
2
25
29

DISTRICT
RANK
2
3
4
5
6
7
1
2
3
4
5
6
7
8
1
2
3

TIER
LEVEL
1
1
2
2
3
3
1
1
1
2
2
3
3
3
1
2
2

Note:
Statewide Rank = Projects ranking statewide
District Rank = Projects ranking within District only
Tier Level = High, medium, and low priority

In some instances, need for a climbing and passing lane may have been identified in the same vicinity. The
TAC recommended leaving the overlaps/duplicates in place to illustrate that those locations were deemed
warranted in both analysis.

15

Figure 2.5: Statewide Climbing Lane (Two-Lane Highways) Rankings

16

CLIMBING LANES ON MULTILANE HIGHWAYS
Methodology for Identification and Ranking
Figure 2.6 illustrates the steps utilized to identify potential candidate locations for climbing lanes on
multilane highways and Figure 2.7 illustrates the steps for prioritization of the candidate locations. Once a
preliminary list of potential candidates was identified, three different prioritization methods (Table 2.5) were
evaluated:
 Option 1 – Subjective Rating Method: In this method, each prioritization criteria was assigned a
weight and a maximum number of points based on discussions with TAC and Districts.
 Option 2 – Z Score Method: In this method, each prioritization criteria is given the same weight.
However, the points/score are determined using a z score value that is based on each record’s
relative distance from the mean of all records. This method is based solely on technical analysis.
 Option 3 – Combined Method: This method represents a combination of subjective and technical
analysis. In this method, the z score from Option 2 is multiplied by weights used in Option 1.

Figure 2.6: Identification Process for Climbing Lanes on Multilane Highways

17

Figure 2.7: Prioritization Process for Climbing Lanes on Multilane Highways

Table 2.5: Prioritization Criteria for Climbing Lanes on Multilane Highways
Option 1: Subjective
Rating Method

Criteria
Mobility
Existing LOS: Existing Density
Proximity to Adjacent Passing/Climbing Lanes
Future LOS: Future Density
Safety
Existing Crash Rate
Existing Crash Severity (EPDO)
Existing Passing Related Crash Rate
Future Crash Severity (Future EPDO)
Construction Feasibility
Cost per Lane Mile
(Low, Medium, or High - Assessed Based on Physical
Constraints)
Bridge Widening Cost
(Low, Medium, High - Assessed based on additional SQFT )
Total Points

Option 2: Z
Score Method
Z Score
(From Analysis)

Option 3: Combined
Method

Points

Overall
Percent

Z Score
(From Analysis)

Overall
Percent

14
8
2
4
20
5
7
4
4
6

35%
20%
5%
10%
50%
13%
18%
10%
10%
15%

35%
10%
5%
5%
50%
13%
18%
10%
10%
15%

3

7.5%

7.5%

3

7.5%

7.5%

40

100%

100%

18

Recommended Prioritization
Table 2.6 presents the list of candidate locations for climbing lanes on multilane highways. The candidate
locations are ranked at the statewide and district level and grouped into three tiers – high, medium, and low
priority. Figure 2.8 illustrates the statewide location of the climbing lanes. Locations identified for climbing

lanes in Table 2.6 represent only the general problem area and not the exact location and length of the
climbing lanes.

Table 2.6: Prioritized List of Climbing Lanes on Multilane Highways
DISTRICT
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Flagstaff
Kingman
Kingman
Kingman
Kingman
Kingman
Kingman
Kingman
Kingman
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Prescott
Safford
Safford
Safford
Tucson
Yuma

CLIMBING LANE LOCATION
(VICINITY)
I 40 EB: MP188 - MP190
I 17 NB: MP307 - MP311
I 17 SB: MP318 - MP316
I 17 NB: MP299 - MP305
I 40 WB: MP193 - MP191
I 40 EB: MP151 - MP152
I 15 NB: MP19 - MP25
I 15 SB: MP21 - MP19
I 40 EB: MP156 - MP159
I 40 WB: MP163 - MP162
I 40 EB: MP47 - MP49
I 40 WB: MP132 - MP136
I 40 EB: MP58 - MP60
I 40 EB: MP81 - MP83
I 40 EB: MP125 - MP128
I 40 EB: MP76 - MP77
I 40 WB: MP115 - MP114
I 40 EB: MP93 - MP97
I 17 NB: MP246 - MP250
I 17 SB: MP281 - MP285
I 17 NB: MP255 - MP256
I 17 SB: MP293 - MP295
I 17 SB: MP284 - MP286
I 17 NB: MP294 - MP298
I 17 SB: MP240 - MP238
I 17 NB: MP270 - MP275
I 10 WB: MP306 - MP302
I 10 EB: MP315 - MP317
I 10 EB: MP309 - MP311
I 10 EB: MP286 - MP291
I 8 EB: MP18 - MP20

TOTAL
POINTS
32.45
27.84
24.15
24.01
20.43
19.08
18.59
16.65
14.19
13.81
25.35
18.56
17.30
17.24
16.32
14.07
12.09
11.48
33.07
30.12
27.27
21.08
20.19
19.06
17.86
14.09
29.51
17.55
12.10
21.01
15.70

STATEWIDE
RANK
2
5
8
9
12
14
16
22
25
28
7
17
20
21
23
27
30
31
1
3
6
10
13
15
18
26
4
19
29
11
24

DISTRICT
RANK
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
1
1

TIER
LEVEL
1
1
2
2
2
2
3
3
3
3
2
3
3
3
3
3
3
3
1
1
1
2
2
2
3
3
1
3
3
2
3

Note: Statewide Rank = Projects ranking statewide; District Rank = Projects ranking within District only;
Tier Level = High, medium, and low priority

19

Figure 2.8: Statewide Ranking of Climbing Lanes on Multilane Highways

20