Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

PUBLICATION NO. FHWA-HRT-23-009 JANUARY 2023 

Lane Line Markings in Advance of 

Lane-Reduction Transitions
FOREWORD

The objective of the Transportation Pooled Fund Program’s Traffic Control Device (TCD) 

Consortium is to assemble a consortium of regional, State, local entities, appropriate 

organizations, and the Federal Highway Administration (FHWA) to establish a systematic 

procedure to select, test, and evaluate existing and new TCDs that will support changes to the 

Manual on Uniform Traffic Control Devices (MUTCD) and interim approvals. 

This report documents a FHWA project examining the comprehension of different 

lane-reduction markings. The goal of this study was to determine the effects of the different 

line-marking patterns in terms of merging behavior at lane-reduction transitions, driver 

understanding of the intended message conveyed at lane-reduction transitions, and perceived 

ranking of effectiveness.

This report is of interest to engineers, planners, and other researchers and practitioners who are 

concerned with the limits of road users’ ability to comprehend and follow roadway 

lane-reduction transitions correctly.

Brian P. Cronin, P.E. 

Director, Office of Safety and Operations 

Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 

(USDOT) in the interest of information exchange. The U.S. Government assumes no liability for 

the use of the information contained in this document. 

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers’ names appear in this report only because they are considered essential to the 

objective of the document. 

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve 

Government, industry, and the public in a manner that promotes public understanding. Standards 

and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality issues and adjusts its programs and processes to 

ensure continuous quality improvement. 

Recommended citation: Federal Highway Administration, Lane Line Markings in Advance of 

Lane-Reduction Transitions (Washington, DC: 2023) https://doi.org/10.21949/1521952 
TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.

FHWA-HRT-23-009

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Lane Line Markings in Advance of Lane-Reduction 

Transitions

5. Report Date

January 2023 

6. Performing Organization Code: 

7. Author(s)

Stacy A. Balk (ORCID: 0000-0003-3886-5117)

and Steven Jackson

8. Performing Organization Report No. 

9. Performing Organization Name and Address

Leidos

6300 Georgetown Pike

McLean, VA 22101

10. Work Unit No.

11. Contract or Grant No.

DTFH61-13-D-00024

12. Sponsoring Agency Name and Address

Traffic Control Devices Pooled Fund Study

13. Type of Report and Period Covered

Final Report; September 2014–February 2016

14. Sponsoring Agency Code

HRSO-30

15. Supplementary Notes

The contraction officer’s representative was David Yang. The government’s task manager was Jim Shurbutt. 

16. Abstract

Roadway lane-reduction transitions have long been reported to be problematic to drivers. Whether this problem is 

the result of a lack of understanding of lane-reduction signing or lane markings, a simple failure to comply with 

such markings, or other unidentified factors is unknown. This study, completed in 2016, explored driver 

comprehension of six different lane-reduction markings. The markings varied in terms of the incorporation and 

length of dotted and broken lines. In addition, half of the markings included a solid white line adjacent to the 

dotted/broken line. The supplemental solid white line resulted in improved understanding that the rightmost lane 

would end, earlier reported lane changes, and the highest preference ratings. Dotted lines also resulted in better 

understanding of an upcoming necessary lane change than did the longer, more traditional broken lane lines. This 

study contains recommendations and suggestions for lane-reduction marking changes to the Manual on Uniform 

Traffic Control Devices. 

17. Key Words

Lane-reduction markings, MUTCD, pavement 

markings

18. Distribution Statement

No restrictions. This document is available to the public 

through the National Technical Information Service,

Springfield, VA 22161.

http://www.ntis.gov

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

24 

22. Price

N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
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iii

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION ................................................................................................ 1

Objectives................................................................................................................................. 3

CHAPTER 2. METHOD .............................................................................................................. 5

Stimuli ...................................................................................................................................... 5

Markings ............................................................................................................................. 5

Marking Options ................................................................................................................. 5

Videos ................................................................................................................................. 8

Stills .................................................................................................................................... 9

Experimental Tasks .............................................................................................................. 10

Task 1 ................................................................................................................................ 10

Task 2 ................................................................................................................................ 10

Task 3 ................................................................................................................................ 11

Task 4 ................................................................................................................................ 11

Participants ............................................................................................................................ 11

Procedure ............................................................................................................................... 11

CHAPTER 3. RESULTS ............................................................................................................ 13

Task 1 ..................................................................................................................................... 13

Task 2 ..................................................................................................................................... 13

Task 3 ..................................................................................................................................... 14

Task 4 ..................................................................................................................................... 15

CHAPTER 4. DISCUSSION ..................................................................................................... 17

Recommendations ................................................................................................................. 18

REFERENCES ............................................................................................................................ 19
iv

LIST OF FIGURES

Figure 1. Illustration. Dotted lane lines used at parallel deceleration lane for exit 

ramp (FHWA 2009). .......................................................................................................1

Figure 2. Illustration. Lane-reduction transition markings (FHWA 2009). .....................................2

Figure 3. Illustration. Broken lines used in markings 1A and 1B....................................................6

Figure 4. Illustration. Dotted lines used in markings 2A and 2B. ...................................................7

Figure 5. Illustration. Dotted lines used in markings 3A and 3B. ...................................................8

Figure 6. Screenshot. Aerial view of marking 3A. ..........................................................................9

Figure 7. Screenshot. Aerial view of marking 3B. ........................................................................10

LIST OF TABLES

Table 1. Overall markings ranks in terms of perceived effectiveness. ..........................................15

Table 2. Proportion of ranking win comparisons by markings. .....................................................15
v 

LIST OF ACRONYMS

FHWA Federal Highway Administration

GLM generalized linear model

MUTCD Manual on Uniform Traffic Control Devices for Streets and Highways 

1 

CHAPTER 1. INTRODUCTION

In the 2009 Manual on Uniform Traffic Control Devices (MUTCD), dotted lane lines (rather 

than broken lines) were adopted as the Federal Highway Administration (FHWA) standard for 

lanes that do not continue ahead beyond the next interchange or intersection (e.g., lane drops, 

auxiliary lanes, deceleration lanes, and acceleration lanes), both on freeways and on conventional 

roads (FHWA 2009). Figure 1 shows an example of dotted lane lines. 

Source: FHWA. 

Figure 1. Illustration. Dotted lane lines used at parallel deceleration lane for exit ramp

(FHWA 2009). 
2 

Per Section 3B.09 of the MUTCD, lane-reduction transitions occur when the number of through 

lanes is reduced between interchanges or intersections. In such cases, where pavement markings 

are used, lane-reduction transition markings shall be used to guide traffic through the transition 

areas (FHWA 2009). An example of lane-reduction transition markings is shown in figure 2. 

Notes: 

1. Lane-reduction arrows are optional 

for speeds of less than 45 mph 

2. See Section 3F.04 for delineator 

spacing 

3. L = WS for speeds of 45 mph or 

greater and L = WS2/60 for speeds 

of less than 45 mph, where: 

L = Length of taper in feet 

S = Posted, 85th-percentile or 

statutory speed in mph 

W = Offset in feet 

4. d = Advance warning distance 

(see Section 2C.05) 

Source: FHWA. 

Figure 2. Illustration. Lane-reduction transition markings (FHWA 2009). 

Dotted lane lines (such as those seen in figure 1) also have been proposed by some engineers for 

use at lane-reduction transitions with the supposition that drivers approaching lane-reduction 

transitions could benefit from the advance warning and demonstrate safer merging behaviors 

with a dotted lane line versus the existing standard marking. Conversely, the lack of any lane line 

marking for three-fourths of the distance from the advance Lane Ends warning sign to the point 

where the taper begins (as the current lane-reduction transition standard calls for) may help to 

reinforce the need to merge early. There is also concern that the use of dotted lines at 
3 

lane-reduction transitions may be confusing to motorists because lane-reduction transitions are 

significantly different from places where dotted lane lines are currently used. In other words, in a 

lane-reduction transition, all vehicles in the ending lane must merge into the adjacent lane, 

whereas in lane drops, vehicles that are unable to leave the lane have the ability to stay in the

lane and proceed to exit or turn. 

To the authors’ knowledge, at the time this project began in 2014, no research studies had been 

produced that examined the effects of dotted-line markings for lane reductions; therefore, 

research was conducted to determine whether the use of a dotted lane line for some distance in 

advance of the lane-reduction is preferable to the longstanding marking pattern for a 

lane-reduction transition (i.e., discontinuation of the normal broken lane line a distance of d/4, or 

one-fourth of the “advance warning distance,” beyond the Lane Ends warning sign) (figure 2).

OBJECTIVES 

The researchers evaluated the existing standard lane-reduction lane line marking pattern as well 

as potential layouts of a dotted line for a lane-reduction transition. The goal of this project was to 

determine the effects of the different line-marking patterns on the following: 

• Merging behavior (i.e., moving into the adjacent lane) at lane-reduction transitions. 

• Driver understanding of the intended message conveyed at lane-reduction transitions 

(from both the terminating lane and the left-adjacent lane). 

• Perceived rankings of effectiveness. 

5 

CHAPTER 2. METHOD

STIMULI 

Design software was used to generate virtual roadways. This software package allowed the 

research team to generate environments using real roadway geographic information system 

(known as “GIS”) data. The researchers were then able to manipulate the roadways as necessary

(e.g., modify roadway lane line markings). After the roadway was built, a “fly through” was

made, which created the illusion of moving through the environment from the drivers’ 

perspective by using a computer animated simulation. 

Markings 

Researchers used five different roadways to present lane-reduction markings. The roadways had

two lanes of traffic in each direction, and they transitioned to one lane of traffic in each direction. 

Design speed for all roads was 40 mph. Taper length was 320 ft. Given the design speed, the 

advanced warning sign (had it been present) would have been placed at 670 ft before the 

beginning of the taper (see table 2C-4 in the MUTCD) (FHWA 2009). Note that the lane 

marking relationship to the taper may vary with different road design speeds. 

Six different lane-reduction markings were created (1A, 1B, 2A, 2B, 3A, 3B). Each was 

presented on five different roadways. In total, 30 different environments were created. Within 

each roadway, the only visual component that varied was the pavement markings—all other 

environmental aspects remained constant. 

To explore exclusively the potential effect of the lane-reduction markings on driver 

understanding and behavior, neither elongated pavement arrows nor Lane Ends signs were 

included. It was suspected that the cues of these two items may overwhelm any potential 

differences in the lane line markings. 

Marking Options

A 3 (broken versus dotted line) × 2 (solid white line) factorial design was used in lane-marking 

combinations. 

1. Broken line versus dotted line: There are three different broken/dotted line combinations 

(labeled numerically).

2. Solid white line: The presence or absence of a solid white line adjacent to the 

broken/dotted line (labeled with alphabetic characters). 

The dotted-line marking does not comply with the 2009 MUTCD. Dotted lane lines are used to 

convey a lane drop rather than a lane reduction. The dotted lane line informs drivers that the lane 

they are in will exit the current traveled way. It does not indicate a merge into the current 

traveled way.
6 

Additionally, the double white lane lines with the solid line on the left and the dashed line on the 

right are not addressed in the 2009 MUTCD. Applying the combination to roadways is not an 

MUTCD-compliant practice. When this report was created in 2016, this lane line configuration 

was undergoing the Request to Experiment process, which is the process used gain 

MUTCD approval. 

Marking 1A was the existing, standard lane-reduction and lane line-marking pattern. Standard 

6-inch-wide broken line pavement markings—each 10 ft in length and spaced 30 ft apart—were 

used in this study. Broken line pavement markings terminated 502.5 ft before the start of the 

taper (figure 3). The 2009 MUTCD states that markings should end at a distance of “advance 

warning distance”/4 beyond the Lane Ends warning sign. 

Source: FHWA. 

Figure 3. Illustration. Broken lines used in markings 1A and 1B.

Marking 1B was the same as marking 1A and included the addition of a solid white line to the 

left of the dotted/standard dashed lines. This line was meant to indicate that traffic in the 

continuing lane should not attempt to move into the ending right lane. The solid white line was 

6 inches wide. It began at 1,005 ft before the start of the taper and terminated at 502.5 ft before

the taper (i.e., the same location where the broken line terminated). The starting distance of the 

solid white line was selected to mirror the roadway distance between the end of the lane line 
7 

markings and the beginning of the taper. In other words, the length of the solid line was 

1.5 × “advanced warning distance” – “advanced warning distance”/4 in length. 

For marking 2A, the standard broken line changed to a dotted line at 1,005 ft (1.5 × “advanced 

warning distance”) before the beginning of the taper; the dotted line pavement markings 

terminated 502.5 ft before the start of the taper (“advanced warning distance”/4) (figure 4). The 

dotted lines were 6 inches wide; they were 2 ft in length and spaced 4 ft apart. Again, this 

marking is noncompliant with the MUTCD.

Source: FHWA

Figure 4. Illustration. Dotted lines used in markings 2A and 2B. 

Marking 2B was the same as marking 2A but included the addition of a solid white line to the 

left of the dotted/standard dashed lines. This line was meant to indicate that traffic in the 

continuing lane should not attempt to move into the ending right lane. The solid white line was 

6 inches wide. It began at 1,005 ft before the start of the taper and terminated at 502.5 ft before

the taper (i.e., the same location where the dotted line terminated). The starting distance of the 

solid white line was selected to mirror the roadway distance between the end of the lane line 

markings and the beginning of the taper. In other words, the solid line was 1.5 × “advanced 

warning distance” – “advanced warning distance”/4 in length. Again, this marking is in the 

Request to Experiment process, but it is noncompliant with the MUTCD. 
8 

For marking 3A, the standard broken line changed to a dotted line at 670 ft (“advanced warning 

distance”) before the beginning of the taper; the dotted line pavement markings terminated as the 

taper began (figure 5). The dotted lines were 6 inches wide; they were 2 ft in length and spaced 

4 ft apart. Again, this marking is noncompliant with the MUTCD.

Source: FHWA

Figure 5. Illustration. Dotted lines used in markings 3A and 3B.

Marking 3B was the same as marking 3A but included the addition of a solid white line to the 

left of the dotted/standard dashed lines. This line was meant to indicate that traffic in the 

continuing lane should not attempt to move into the ending right lane. The solid white line was 

6 inches wide. It began at 1,005 ft before the start of the taper and terminated as the taper began 

(i.e., the same location where the dotted line terminated). Again, this marking is in the Request to 

Experiment process, but it is noncompliant with the MUTCD. 

Videos 

Thirty videos (consisting of six different markings for five different roadways) concluded at the 

beginning of the roadway taper. An additional five videos (one for each of the five different 

roadways) were created in a neutral section, where the roadway did not taper (i.e., all travel lanes 

continue). These additional five videos were used as “control” or “catch” videos to ensure that 

participants were responding to the different stimuli presented. All videos simulated a driver’s 
9 

perspective traveling at 36 mph for 2,000 ft. Each video’s duration was approximately 38 s. 

Videos were presented on a 60-inch LCD/LED 1080i television screen. 

Stills 

Aerial still shots were captured for all six pavement markings in a single environment. Stills 

included a 24-inch by 36-inch poster showing a longer approach as well as 18-inch by 24-inch

zoomed-in images. Examples of two of the zoomed-in images can be seen in figure 6 and

figure 7. 

Source: FHWA. 

Figure 6. Screenshot. Aerial view of marking 3A.
10 

Source: FHWA

Figure 7. Screenshot. Aerial view of marking 3B. 

EXPERIMENTAL TASKS

Task 1 

The goal of task 1 was to determine if participants traveling in the rightmost lane (with lane

reduction) were able to understand that their lane was going to end. Participants were shown 

videos from the driver’s perspective in the far-right lane. After the video concluded, participants 

were asked two questions: 

1. Are you allowed to continue to travel in the right lane? (yes or no) 

2. If you continued to travel in this lane, what, if anything, would happen? (open answer)

Task 2 

The goal of task 2 was to determine if participants traveling in the lane just to the left of the 

ending lane were able to understand that the right lane was going to end. Participants were 

shown videos from the driver’s perspective in the left lane (the nonterminating lane that 

continued). After the video concluded, participants were asked two questions: 
11 

1. May you merge into the right lane? (yes or no)

2. What, if anything, might you expect the traffic in the right lane to do? (open answer) 

Task 3 

The goal of task 3 was to determine how quickly participants traveling in the rightmost lane 

(with lane reduction) were able to understand that their lane was going to end and would 

subsequently change lanes. Participants were shown videos from the driver’s perspective in the 

far-right lane. Participants were told: “Imagine that you are driving down the roadway. While 

you are driving, you may need to change lanes to continue travel. As soon as you are confident 

that you need to change lanes, click the mouse.”

Task 4 

The goal of task 4 was to determine participants’ preferences for the different lane markings. 

Participants were shown stills of all six of the markings and were encouraged to move around 

and to look as closely as desired at the markings. Participants were asked to answer the 

following questions: 

1. There are several different ways in which roadway lane markings can be placed to 

indicate to drivers that the lane is about to end. Imagine that you are traveling

northbound. Please rank the different pavement markings in terms of their 

effectiveness in indicating that the right lane is about to end. 

2. In your opinion, what aspects of your highest ranked set of markings helps to make 

them more effective?

3. What, if anything, might you change in order to increase people’s understanding of 

the lane ending road markings? 

4. Which set of markings do you encounter most frequently in the areas that you drive? 

5. Additional comments. 

PARTICIPANTS

A total of 90 people (51 males) with ages ranging from 19 to 77 yr (mean [M] = 45.23 yr) 

participated. Each person was paid $40. 

PROCEDURE

On arrival, participants were given a brief overview of the experiment, and each completed an 

informed consent document. Each participant was then assigned to task 1, task 2, or task 3. 

A brief, visual screening was performed to ensure a minimum of 20/40 acuity (the minimum to 

obtain a driver’s license in most States). Next, participants were provided more specific 

instructions for their assigned tasks, were provided practice trials, and were given opportunities

to ask any questions. 
12 

Participants were allowed to take breaks to stretch and to rest their eyes as needed. On 

completion of the assigned tasks, all participants completed task 4 (subjective preference of 

lane-reduction markings). In other words, all participants completed two tasks. Total 

participation time ranged from 30 to 50 min, depending on participant response speed.
13 

CHAPTER 3. RESULTS

TASK 1 

Again, the goal of task 1 was to determine if participants traveling in the rightmost lane 

understood that their lane would end and that they would need to move out of that lane. 

A repeated-measures generalized linear model (GLM) (binomial response distribution, logit link 

function) was used to determine the influence of lane markings on participant response. 

A response of “no” to the question, “Are you allowed to continue to travel in the right lane?” was 

considered correct. 

Overall, the presence of the solid line to the left of the broken or dotted line (markings A versus

markings B) did not affect responses, χ2

(1) = 2.94, p > 0.05. 

Overall, the variation of dotted or broken lines significantly affected participant responses, 

χ2(2) = 16.94, p = 0.0002. 

Marking set 3 generated significantly more correct responses (must move out of the lane) than 

both marking set 2 (p < 0.001) and marking set 4 (p = 0.003). The responses to marking set 2 

were similar to those responses to marking set 1 (p > 0.05). 

The interaction between the addition of the solid white line and broken/dotted lines did not 

significantly affect participant response, χ2(2) = 0.52, p > 0.05. 

In general, those participants who responded correctly demonstrated their understanding of the 

roadway markings in their responses to the question, “If you continued to travel in this lane, 

what, if anything, would happen?” Most participants indicated that the lane would end, that they

would need to merge, or they otherwise responded with a similar answer. 

Those participants who incorrectly responded to the yes-or-no question demonstrated their lack 

of understanding in their responses to the open-ended answers. Their comments were that

nothing would happen, that they should continue straight, or they otherwise responded with a 

similar answer.

TASK 2 

Again, the goal of task 2 was to determine if participants traveling in the lane just to the left of 

the ending lane were able to understand that the right lane was going to end and that they should 

expect traffic to move from the right lane into the left lane. 

A repeated-measures GLM (binomial response distribution, logit link function) was used to 

determine the influence of lane markings on participant response. A response of “no” to the 

question, “May you merge into the right lane?” was considered correct. 

Overall, the presence of the solid line to the left of the broken or dotted line (markings A versus

markings B) significantly affected participant response, χ2

(1) = 34.46, p < 0.0001. The presence 
14 

of the solid white line (markings B) resulted in significantly more correct responses than the 

absence of the solid line (markings A). 

When markings that included the broken line were compared to markings that included the 

dotted line, no significant effect on participant responses was found, χ2

(2) = 1.36, p > 0.05. The 

interaction between the addition of the solid white line and broken/dotted lines did not 

significantly affect participant response, χ2(2) = 4.12, p > 0.05. 

As in task 1, participants demonstrated their understanding of the lane markings when 

responding to the free response question, “What, if anything, might you expect the traffic in the 

right lane to do?” Those who answered the yes-or-no question correctly overwhelmingly 

responded with an indication that the traffic in the rightmost lane would be merging into the left 

lane. For example, responses included “merge into the left lane,” “switch lanes,” and “expect 

them to yield.” However, those who responded incorrectly to the yes-or-no question frequently 

failed to indicate that it was understood that the right lane would end. For example, responses 

included, “continue straight” and “nothing.” 

TASK 3 

The goal of task 3 was to determine how quickly participants traveling in the rightmost lane 

(with lane reduction) were able to understand that their lane was going to end and would 

subsequently change lanes. 

A repeated measures GLM (normal response distribution) was used to determine the influence of 

lane markings on participant response time. 

Overall, the presence of the solid line to the left of the broken or dotted line (markings A versus

markings B) significantly affected participant response times, χ2

(1) = 42.20, p < 0.0001. The 

presence of the solid white line (markings B) resulted in significantly faster responses 

(M = 21.31 s) compared to those responses with the absence of the solid line (markings A; 

M = 23.64 s). 

Overall, the variation of dotted/broken lines significantly affected participant response times, 

χ2(2) = 289.56, p < 0.0001. Marking set 2 resulted in the fastest response times (M = 19.29 s), 

p < 0.0001. Marking set 1 (M = 21.97 s) resulted in significantly faster response times than 

marking set 3 (M = 26.156 s), p < 0.0001. 

The interaction between the addition of the solid white line and broken/dotted lines significantly 

affected participant response times, χ2

(2) = 29.30, p < 0.0001. Within marking set 1, the presence 

of the solid line (markings B) significantly reduced response time (M = 19.44 s) compared to the 

response times with the absence of the solid line (markings A; M =24.51 s), p < 0.0001. 

Within marking set 2, the presence of the solid line (markings B) did not significantly affect 

response times (M = 18.84 s) compared to the response times with the absence of the solid line 

(markings A; M =19.74 s), p > 0.05. Within marking set 3, the presence of the solid line 

(markings B) did not significantly affect response times (M = 25.65 s) compared to response 

times with the absence of the solid line (markings A; M = 24.51 s), p > 0.05. 
15 

TASK 4 

The goal of task 4 was to determine participants’ preferences for the different lane markings. 

Participants were asked to rank the different pavement markings in terms of their perceived 

effectiveness in indicating that the right lane is about to end. Overwhelmingly, the markings with 

the solid white line (markings B) were ranked higher than those without the solid white line 

(markings A). Markings 3 were rated better than markings 2 and markings 1. Markings 2 were 

ranked higher than markings 1. Table 1 provides overall rank of each set of markings. 

Table 1. Overall markings ranks in terms of perceived effectiveness.

Rank Markings

1 3B

2 2B

3 1B

4 3A

5 2A

6 1A

Table 2 shows the Condorcet win/loss rates for each of the markings. Each cell depicts the 

proportion of time that the row markings would have been selected over the column markings 

had the two markings been directly compared. For example, markings 3B was selected as higher 

rated than markings 1A 87 percent of the time. 

Table 2. Proportion of ranking win comparisons by markings. 

Markings 1A 1B 2A 2B 3A 3B

1A — 0.15 0.07 0.11 0.12 0.13

1B 0.85 — 0.55 0.24 0.55 0.28

2A 0.93 0.45 — 0.29 0.44 0.35

2B 0.89 0.76 0.71 — 0.66 0.49

3A 0.88 0.45 0.56 0.34 — 0.24

3B 0.87 0.72 0.65 0.51 0.76 —

—No data. 

17 

CHAPTER 4. DISCUSSION

The goal of this work was to assess drivers’ understanding of both new and traditional 

lane-reduction roadway markings. Drivers participated in different tasks to determine the effects 

of the different lane marking patterns in terms of the following: 

• Merging behavior (i.e., moving into the adjacent lane) at lane-reduction transitions. 

• Driver understanding of the intended message conveyed at lane-reduction transitions 

(from both the terminating lane and the left-adjacent lane). 

• Perceived rankings of effectiveness. 

When participants were positioned in the rightmost lane that was ending and requiring traffic to 

merge, the addition of the solid white line did not affect the understanding that the lane would 

end and a lane change was required. However, marking set 3 (dotted line to the beginning of the 

taper) generated the most correct responses as indicated by the knowledge that the rightmost 

travel lane would end, and a lane change was required. Dotted lines are currently endorsed only 

when a lane drops, and there is concern that the use of dotted lines at lane-reduction transitions 

may be confusing to motorists, given lane-reduction transitions are significantly different from 

lane drops. However, no evidence of confusion was found in this study. Future work could 

explore how well drivers differentiate between land-reduction and lane-drop situations. 

When participants were positioned in the left-adjacent lane to the terminating lane, the addition 

of the solid white line (markings B) helped drivers to understand that the right lane was going to 

end and that they should not attempt to move into that lane. Subsequently, open-ended questions 

confirmed a greater understanding that the traffic in the right lane would be expected to merge 

into the adjacent lane because of a lane reduction. 

A group of participants was asked to indicate when they were confident that they would need to 

change lanes. The solid white line (markings B) significantly reduced participant response time 

by 2.33 s. At 40 mph, this reduction provides drivers an additional 136.87 ft to change lanes. In 

terms of dotted lines versus broken lines, marking set 2 generated the fastest response times, 

followed by marking set 1, and finally marking set 3. This finding may seem a bit challenging to 

interpret. Although not specifically tested as a variable, the location where the lane markings 

terminate influences when a driver is confident that the lane will end and when he or she will 

elect to change lanes. In other words, both marking set 2 and marking set 1 terminate lane 

markings at “advanced warning distance”/4, whereas marking set 3 continues markings until the 

beginning of the taper. Evidence from this study suggests that the termination of the markings 

acts as a cue to change lanes. However, an active driving study may help to confirm this finding. 

These results taken together lead to several conclusions: 

• The addition of a solid white line results in earlier lane changes, an understanding that 

drivers in an adjacent lane should not move into a lane that is about to terminate, and an 

understanding by drivers in an adjacent lane that they should expect merging traffic. 
18 

• Dotted lines (as opposed to broken lines) result in greater understanding that a lane is 

about to end. 

• Drivers subjectively perceive the addition of the solid white line in lane-reduction 

markings to be helpful in indicating a lane reduction. 

• Drivers subjectively perceive dotted lines to be more effective than the broken line alone.

RECOMMENDATIONS

Researchers have several recommendations based on the results of this laboratory study. These 

recommendations, however, would need to undergo the full MUTCD experimentation process 

before being implemented: 

1. Add a solid white line to the left of broken/dotted lane markings in lane-reduction

situations. This addition may help drivers to understand that a lane is ending. This 

addition is especially pertinent in situations in which drivers are: 

a. Frequently moving into a lane that is about to terminate. 

b. Not allowing other drivers to merge from a terminating lane. 

c. Taking too much time to begin merging out of a terminating lane. 

2. Allow the usage of the dotted line in place of the broken line to indicate a 

lane-reduction. However, this study recommends that a more full-scale study (either 

via active driving simulation or real-world application) be performed to determine if 

marking set 2 or marking set 3 is more effective in the real world. Although marking 

set 3 generated more correct responses in terms of understanding that the right lane

would end, marking set 2 generated faster response times. At this time, is it is unclear 

if one set of markings might cause more traffic problems (e.g., waiting to merge until 

the taper).

3. Future work should include the investigation of lane-reduction signage, delineation 

markers, and pavement arrows as they supplement lane-reduction 

pavement markings.
19 

REFERENCES

Federal Highway Administration. 2009. Manual on Uniform Traffic Control Devices. 

Washington, DC: Federal Highway Administration. 

https://mutcd.fhwa.dot.gov/pdfs/2009r1r2r3/mutcd2009r1r2r3edition.pdf, last accessed 

July 22, 2022. 
HRSO-30/01-23(WEB)E Recycled

Recyclable

Recommended citation: Federal Highway Administration, Lane Line Markings 

in Advance of Lane-Reduction Transitions (Washington, DC: 2023) 

https://doi.org/10.21949/1521952