Evaluation of Additional 

Alternatives of, and Arrow Sizes 

for, Overhead Arrow-Per-Lane 

Guide Signs

FHWA Publication No.: FHWA-HRT-23-036

FHWA Contact: Laura Mero, Office of Safety Research 

& Development, 202-493-3377, Laura.Mero@dot.gov

INTRODUCTION

Complex interchanges with multiple exit lanes, including an option lane, 

can be confusing to navigate. Roadway signs provide navigational, lane 

assignment, and roadway geometry information that explain complex 

interchanges to drivers. Well-designed roadway signs help drivers make 

timely and accurate decisions. Signs that are confusing or that violate driver 

expectations may lead to unnecessary lane changes, sudden lane changes, and 

mistakes that may compromise roadway system efficiency and driver safety.

The Manual on Uniform Traffic Control Devices for Streets and Highways

(MUTCD) (FHWA 2009) requires overhead arrow-per-lane (OAPL) guide 

signs or diagrammatic guide signs at multilane exit interchanges and splits 

with an option lane on freeways and expressways. Diagrammatic signs show 

a graphic view of the roadway with lane assignment for the through and 

exiting lanes (figure 1). OAPL guide signs use an upward pointing or curved 

arrow for each lane centered over the lane to indicate lane assignment for the 

through and exiting movements (figure 2). Both sign types also include text 

and route shields to indicate destinations accessible by each lane.

TECHBRIEF

Research, Development, 

and Technology

Turner-Fairbank Highway 

Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

https://highways.dot.gov/research

Figure 1. Illustration. Diagrammatic guide sign for a multilane 

exit with an option lane (MUTCD figure 2E-7) (FHWA 2009).

Source: FHWA.
2

Previous research suggested that overhead signs with 

specific lane assignment information better support 

driver decisions and lane choice at interchanges than 

diagrammatic guide signs. The use of an individual 

arrow for each lane on guide signs is more effective 

in communicating lane assignment information than 

a graphic view of the entire roadway lane assignment 

displayed in one arrow (Brackett et al. 1992). 

Furthermore, drivers readily understand the relationship 

between specific lanes and corresponding destinations 

displayed by overhead signs with specific lane 

assignment information (Richard and Lichty 2013). 

Golembiewski and Katz (2008) found that drivers 

made significantly more correct lane choices and 

comprehended a sign configuration showing one 

arrow per lane compared to diagrammatic signs. 

Fitzpatrick et al. (2013) also found that OAPL signs 

were superior for helping drivers make correct lane 

choices compared with diagrammatic signs.

OAPL signs support quick and accurate lane choice 

decisions but are generally more expensive to construct 

than other advance guide signs. OAPL guide signs 

are larger than conventional diagrammatic signs and 

require costly support structures. The signs are wider 

to accommodate showing an arrow over each travel 

lane and taller to accommodate the required 66-inch 

through arrows. OAPL guide signs cannot make use 

of existing cantilevered mounting structures and require 

more substantial structures that span the entire roadway. 

Furthermore, even an existing support structure that 

spans the entire width of the roadway may need to be 

replaced to support an OAPL if it cannot support wind 

loads striking the larger sign.

Also, OAPL signs that comply with the current MUTCD 

provisions may be impractical in some applications. 

Minor and intermediate interchanges can be closely 

spaced in urban areas. OAPL signs occupy most of the 

space on a sign structure and may leave insufficient space 

for providing information about downstream interchanges 

(National Committee on Uniform Traffic Control 

Devices 2012a).

The provisions in the current version of the MUTCD 

(FHWA 2009) require that the OAPL sign include an 

arrow for each lane on the sign over the center of the 

lane, resulting in a large sign. Some agencies have 

proposed using a smaller, modified versions of OAPL 

guide signs as an alternative to OAPL guide signs. The 

smaller signs are less expensive and, in many cases, 

may be installed on existing cantilevered mounting 

structures. However, like their full-sized counterpart, 

these modified OAPLs, hereafter referred to as 

partial-width OAPL, use upward-pointing and curved 

arrows to communicate lane assignment and direction 

of travel. Though similar, partial-width OAPL signs 

display curved arrows only for the exit lanes. They show 

a bifurcated arrow for the option lane that serves both 

the through and exit movement, eliminating the straight 

arrows for only the through-route lanes.

As there is not a standard for a partial-width OAPL, the 

design characteristics (e.g., arrow size) and placement 

of signs are inconsistent. The MUTCD requires 

standardized arrows that are a height of 66 inches 

(FHWA 2009). However, some agencies have changed 

the arrow size and proportions on partial-width signs. 

Research has been limited on the effect smaller arrow 

sizes has on driver comprehension and effectiveness.

Fisher et al. (2004) used a driving simulator to evaluate 

six guide sign alternatives for two-lane freeway exits 

with an option lane in a simulated tunnel environment. 

Figure 2. Illustration. OAPL guide sign for a multilane exit with an option lane (MUTCD figure 2E-3) (FHWA 2009).

Source: FHWA.
3

Results found that every driver correctly exited when 

shown an OAPL sign, and slightly more than one-third 

made an unnecessary lane change. A partial-width 

version of the sign with down arrows over each exit 

lane and a pull-through sign for the through lanes 

was effective at reducing the likelihood that drivers 

missed the exit. However, 50 percent of the drivers 

unnecessarily changed lanes from the option lane to the 

auxiliary lane when exiting, and 44 percent of drivers 

unnecessarily changed lanes from the option lane to 

the through lane when continuing the mainline. The 

authors acknowledged that the unnecessary lane changes 

may be attributed to the partial-width sign’s arrows not 

explicitly indicating that the option lane continued into 

the mainline.

The Traffic Control Device Pooled Fund Study (TCD PFS) 

was formed to conduct research to provide traffic control 

device solutions to State department of transportations 

(DOTs). Under a previous study funded by the TCD PFS, 

Dagnall, Katz, and Bertola (2013) examined five different 

signing series that present information about an upcoming, 

multilane exit interchange with an option lane. This study 

included the following signs:

• Partial-width (referred to as truncated in the 

referenced study) OAPL guide sign with only option 

lane and exit-only lane information, i.e., no through 

movement information.

• MUTCD-compliant OAPL guide sign 

(MUTCD figure 2E-3).

• Partial-width OAPL guide sign with a pull-through 

sign (MUTCD figure E6-2a).

• MUTCD-compliant sign at intermediate and minor 

interchanges with multilane exits that include an 

option lane, when OAPL or diagrammatic guide 

signs are not warranted (MUTCD figure 2E-11).

• Conventional arrow guide sign that conveys the 

presence of option lanes.

Participants watched videos simulating freeway travel 

and were prompted to indicate the lanes they could and 

could not use to reach their destination (both the exiting 

destination and through destination). The full-sized 

OAPL guide sign and partial-width OAPL with a 

pull-through sign were the most effective at helping 

participants correctly indicate the lanes that would reach 

the destination. However, using partial-width OAPL 

may not be feasible in all cases. As with full-sized 

OAPL, partial-width OAPLs require overhead structures 

on which to install the signs.

Consistent sign design and practices are critical 

for supporting driver expectations and accurate, 

timely navigation decisions (Jackson et al. 2018). 

Additional research on partial-width OAPL guide 

sign design and arrow sizing must occur to inform 

practitioners and support consideration for future 

adoption in the MUTCD. This study, conducted 

under the TCD PFS, evaluated the effectiveness of 

various partial-width OAPL guide sign designs and 

arrow sizes for communicating the destination and 

direction that each lane serves for drivers approaching 

single and multiple closely spaced exits at minor and 

intermediate interchanges.

OBJECTIVES

This research explored alternative partial-width 

overhead signs and arrow sizing, including arrow height, 

proportionality, and form proportionate to the size of the 

sign to quantify driver comprehension and understanding 

on different roadway geometries. The objectives of this 

study were to understand driver’s:

• Comprehension of partial-width OAPL guide sign 

configuration alternatives.

• Understanding of the roadway and exit lane 

geometry associated with partial-width OAPL 

guide sign alternatives, especially for too closely 

spaced exits.

• Comprehension and understanding of the sign 

alternatives and roadway geometry changes 

based on different locations of the sign legend 

and “EXIT ONLY” message.

• Lane changing behavior for each signing alternative.

• Comprehension of the arrow sizes.

• Understanding of time required for drivers to 

comprehend each arrow size and signing alternative.

• Preferences among the alternatives of arrow sizes 

and signs.

VARIABLES

This research included three multilevel, independent 

variables.

Roadway Geometry

The research team evaluated the following four roadway 

geometries. Figure 3 shows schematic diagrams of the 

roadway geometries. The MUTCD has a provision for 

OAPL guide signs on single-exit roadway (roadway 
4

geometry 1). The other three roadway geometries have 

two, closely spaced (0.5 mi from the first exit) exits.

• Roadway geometry 1: Dual-lane exit with option lane 

and without a downstream exit.

• Roadway geometry 2: Dual-lane exit with option lane 

followed by downstream exit with auxiliary lane. 

• Roadway geometry 3: Dual-lane exit with option lane 

followed by downstream exit with dropped lane. 

• Roadway geometry 4: Dual-lane exit with option lane 

followed by downstream dual-lane exit with dropped 

and option lane.

Figure 3. Illustration. Roadway geometries 1, 2, 3, and 4 (from left to right).

Source: FHWA.

Sign Configurations

The study compared five sign configurations. The signs 

had a letter height of 20 inches, 20-inch uppercase and 

15-inch lowercase loop height, and 48-inch route marker. 

The five sign configurations had slightly different 

exit information between single-exit and dual-exit 

roadway geometries.

Sign Configuration 1: OAPL Guide Sign for 

a Multilane Exit with an Option Lane

Sign configuration 1 is the compliant guide sign required 

for use at major interchanges and recommended for minor 

and intermediate interchanges that have multilane exits 

with an option lane (FHWA 2009). This sign does not 

address closely spaced interchanges. Figure 4 shows sign 

configuration 1 for the single-exit roadway geometry.
5

Figure 4. Illustration. Sign configuration 1: OAPL guide sign for a multilane exit with an option lane.

Figure 5. Illustration. Sign configuration 2: Partial-width OAPL with pull-through.

Figure 6. Illustration. Sign configuration 3: Partial-width OAPL without vertical separator or pull-through sign.

Source: FHWA.

Source: FHWA.

Source: FHWA.

Sign Configuration 2: Partial-Width OAPL 

with Pull-Through

Sign configuration 2 is the partial-width OAPL guide 

sign with a separate pull-through sign (Dagnall, Katz, 

and Bertola 2013). Figure 5 shows sign configuration 2 

for the single-exit roadway geometry.

Sign Configuration 3: Partial-Width OAPL 

without Vertical Separator or Pull Through Sign

Sign configuration 3 used the same partial-width OAPL 

guide sign design as sign configuration 2 minus the 

vertical separator for the through route. In addition, this 

configuration does not include the secondary pull-through 

sign. See figure 6 for sign configuration 3 for the single-exit 

roadway geometry.
6

Sign Configuration 4: Partial-Width OAPL with 

Vertical Separator and without Pull-Through Sign

Sign configuration 4 used the same partial-width OAPL 

guide sign design as sign configuration 2. However, this 

configuration did not include the secondary pull-through 

sign. Figure 7 shows sign configuration 4 for the 

single-exit roadway geometry. 

Sign Configuration 5: Partial-Width OAPL 

without Vertical Separator with Pull Through

Sign configuration 5 used the same partial-width OAPL 

guide sign design as configuration 2. However, this 

Figure 7. Illustration. Sign configuration 4: Partial-width OAPL with vertical separator and without pull through sign.

Figure 8. Illustration. Sign configuration 5: Partial-width OAPL without vertical separator.

Source: FHWA.

Source: FHWA.

configuration did not include the vertical separator 

on the partial-width sign. Figure 8 shows sign 

configuration 5 for the single-exit roadway geometry.

As noted previously in the Introduction section, 

sign configurations 1–5 were adjusted to provide 

information about multiple, closely spaced exits for 

roadway geometry 2–4 (dual exits). Figure 9 shows 

configurations 1–5 in this order as adapted for a roadway 

geometry with a closely spaced downstream exit. 

This set of signs presents the information about the 

downstream exit and the destination associated with it.
7

Figure 9. Illustrations. Sign configurations 1–5 when applied to a closely spaced downstream exit 

(roadway geometries 2–4).

Source: FHWA.

A. Sign Configuration 1.

B. Sign Configuration 2.

C. Sign Configuration 3 

D. Sign Configuration 4.
8

Figure 9. Illustrations. Sign configurations 1–5 when applied to a closely spaced downstream exit 

(roadway geometries 2–4). (Continued)

Figure 10. Illustration. Arrow designs 1, 2, 3, and 4.

Source: FHWA.

Source: FHWA.

Arrow Designs

The study evaluated several arrow designs (figure 10). 

The only arrow design and dimensions that comply with 

the 2009 MUTCD is arrow design 1. All others are not 

compliant with the MUTCD Researchers repeated sign 

configurations to include different arrow designs, and 

they manipulated arrow design as an independent variable 

between subjects. 

• Arrow design 1: 21.625-inch type D directional 

arrowhead with an 8-inch-wide arrow shaft and height 

of 66 inches.

• Arrow design 2: 21.625-inch type D directional 

arrowhead with an 8-inch-wide arrow shaft and height 

of 42 inches.

• Arrow design 3: 21.625-inch type D directional 

arrowhead with a 7-inch-wide arrow shaft and height 

of 48 inches and turn arrow shaft extension rotated to 

54 degrees from 68 degrees.

• Arrow design 4: 21.625-inch type D directional 

arrowhead with a 6-inch-wide arrow shaft and a 

height of 48 inches and turn arrow shaft extension 

rotated to 54 degrees from 68 degrees.

E. Sign Configuration 5.
9

Figure 11. Photo. Experimental set up.

Figure 12. Screenshot. Lane choice options presented on screen.

Source: FHWA.

Source: FHWA.

METHODS

The study experiment included two parts to address all 

research objectives.

Part 1—Arrow Design, 

Dynamic Visualizations

During the dynamic visualization portion of this 

experiment, participants watched a 15-s video containing 

a randomly assigned sign configuration and roadway 

geometry. The visualization simulated traveling at 

approximately 55 mph on an 8-lane, divided highway. 

In each visualization, the point of view was from the 

second lane from the right, which became the option 

lane and aligned with the bifurcated arrow on the 

sign. The study took place at the Turner-Fairbank 

Highway Research Center Sign Lab. The Sign Lab 

includes a 60-inch liquid crystal display monitor. The 

monitor is capable of telecasting from the visualization 

software. Participants used a keyboard to interact with 

the visualization displayed on the monitor. Figure 11

shows the experimental set up. Researchers instructed 

participants to use the space bar of the keyboard to stop 

the video as soon as they understood the destination 

information conveyed on the sign. The length of each 

video was approximately 20 s.

Figure 12 shows the picture that displayed when 

participants pressed the space bar on the keyboard, 

terminating the dynamic video. Using the number pad, 

participants selected a lane—1 to 4.

Participants responded to the following questions: 

1. If you were traveling to Dallas, what lane(s) could 

you take?

2. If you were traveling to Waco, what lane(s) could 

you take?

3. If you were traveling to Plano, what lane(s) could 

you take?
10

Across all trials, Dallas was the through destination, Waco 

was the exit destination, and Plano was the downstream 

exit destination. Therefore, in single-exit roadway 

geometry trials, question 3 was not asked. After answering 

the lane choice questions, participants were asked how 

confident they were in their answers on a scale of 1 to 5, 

where 1 is not at all confident and 5 is very confident.

For part 1 of the experiment, researchers randomly 

assigned participants to one of four arrow design groups. 

Within each arrow design, participants received exposure 

to all combinations of sign configurations and roadway 

geometries. The 80 trial configurations can be seen in 

the appendix of this document. Part 1 included videos 

showing signs placed 1 mi upstream of the exit gore, a 

0.5 mi upstream of the exit gore, and at the exit location. 

Each participant viewed 60 videos.

Part 2—Questionnaire

As figure 13 shows, the questionnaire design focused on 

evaluating participant perceptions about the effectiveness 

of the 5 sign configurations and 4 arrow designs as part 

of a sign, resulting in 20 total questions. Figure 13 shows 

all arrow designs for one sign configuration. The question 

asked was, “If you saw the sign in the box while driving, 

how easy would it be for you to see and understand the 

arrows on the sign?” Participants answered the question 

by choosing an option from 1 to 5.

Figure 13. Screenshot. Arrow design preference.

Source: FHWA.

To answer each question on the effectiveness of the sign 

configurations, participants saw a still image from the 

videos used in part 1 that displayed the sign of interest 

over a four-lane road superimposed with letters that 

labeled each lane of the highway. Red circles were used 

to identify the specific lane(s) that a driver could take to 

get to a specified destination. Figure 14 shows an example 

of a question. Participants selected a number defining 

how effective they thought each sign was at conveying 

the specific lane assignment information. Numbers 

ranged from 1 (not effective) to 5 (very effective). 

Questions appeared in random order. All the participants 

encountered the same set of questions for the same set of 

sign configurations.

Visualization Development

Researchers used several software suites to develop 

sign stimuli and dynamic visualizations for this study. 

They used drawing software to develop the signs 

to guarantee appropriate sign and arrow designs, 
11

Figure 14. Screenshot. Visual aid to rate effectiveness of sign configurations.

Source: FHWA.

spacing, and proportionality. To create the roadway 

geometry and supplemental animations, the study 

used three-dimensional modeling and animating tools. 

Researchers developed 240 unique visualizations across 

the 4 arrow designs and roadway geometries.

Participants

Data collected for this research came from 112 participants, 

56 male and 56 female. Researchers further split the male 

and female groups by age as young (< 46-yr-old) or older 

(≥ 46-yr-old) participants. There were 28 younger males 

and 28 older males in the study. In the female participant 

group, 28 participants were younger and 28 were older. 

Binning participants by gender and age was done this way 

to ensure representation from all age and gender to remove 

confounding effects of age and gender in the dataset. 

Most participants were unfamiliar with the locations used 

in the sign configuration. Similar level of familiarity 

among participants helps reduce biases. However, most 

participants were familiar with overhead arrow signs used 

in this research. 

DATA ANALYSIS AND RESULTS

Data from 112 participants were used for the analysis. 

Response times associated with each sign configuration 

and confidence in selected answers, sign preference and 

arrow designs are different types of independent variables 

used in this study. Researchers manually scored accuracy 

of lane choices to produce the dataset. They also produced 

descriptive statistics and data visualizations to identify 

trends or patterns in the dataset. Applying generalized 

estimating equations (GEE) to the dataset detected 

statistically significant differences in participant groups 

based on dependent variables: response times, lane choice 

accuracy or response accuracy, confidence in lane choice, 

confidence in question answers, and preference of signs 

and arrow designs.

Response Time

Participants saw a video containing a road scenario 

in which they approached an overhead sign. The 

simulated approach speed was the equivalent of 55 mph. 

Researchers instructed participants to use the keyboard 

to stop the scenario once they comprehended the sign. 

Response time represented how quickly or slowly 

a participant comprehended a sign. Response time 

started at the beginning of the scenario and ended at the 

time the participant pressed the keyboard space bar to 

stop the video.

Average Response Time on Different 

Roadway Geometry

Figure 15 presents participant average response times for 

all sign configurations on all roadway geometries. For 

signs 1 mi from the exit location, sign configuration 1 

had the shortest average response time of 10.8 s. Sign 
12

Figure 15. Graph. Average response times for different sign configurations on different roadway geometries.

Source: FHWA.

configuration 3 had the longest average response time of 

13.1 s on roadway geometry 3. The difference between 

the shortest and longest response time was 2.3 s among 

all sign configurations across the roadway geometries.

For the 0.5-mi location, sign configuration 1 had the 

shortest response times of 10.8 s for roadway geometries 1 

and 2. Sign configuration 1 on roadway geometry 4 

had the longest average response time of 12.5 s. Sign 

configuration 4 also had a 12.5-s average response time on 

roadway geometry 4. The difference between the shortest 

and longest response times was 1.7 s.

For the 1-mi location, sign configuration 1 relates to 

the shortest average response time of 10.8-s average 

response time on roadway geometry 1. The longest 

average response time of 12.7 s was captured for sign 

configuration 4 on roadway geometry 4. The difference 

between the maximum and minimum average response 

times among sign configurations across roadway 

geometries was 2.4 s. 

Except for roadway geometry 4, figure 15 shows that 

average response times were shortest for roadway 

geometries 1 and 2. Roadway geometry 1 is the 

single-exit configuration. Roadway geometry 2 is a 

dual-exit configuration with an auxiliary lane. No 

consistent pattern was observed in average response 

times for the other four sign configurations.

Sign configuration 1 had shorter response times than 

other sign configurations on all roadway geometries 

except roadway geometry 4. There was no consistent 

pattern observed in average response times for other four 

sign configurations.

Response Times with Different Arrow Designs

Figure 16 presents average response times associated 

with different sign configurations and different 

arrow designs. For signs 1 mi from the exit location, 

participants had the shortest response time for 

configuration 1. Participants recorded the longest average 

response time for sign configuration 5 with arrow 

design 4. The minimum and maximum response times 

were 11 and 13.3 s, respectively. The difference was 

2.3 s across all arrow designs.

On the 0.5-mi location, sign configuration 1, participant 

average response time was 10.6 s, the shortest response 

time with arrow design 1. For sign configuration 4, 

participant average response time was the longest at 

12.7 s with arrow design 4. The difference was 2.1 s.

At the exit location, participants recorded the shortest 

average response time of 10.6 s for sign configuration 1 

with arrow design 1. For sign configuration 4 with arrow 

design 4, participants had the longest average response 

time of 13 s. The difference was 2.4 s between the 

shortest and longest average response times.
13

Figure 16. Graph. Average response times of different sign configurations over different arrow designs.

Source: FHWA.

Participant average response time for sign configuration 1 

with arrow design 1 and arrow design 3 was the shortest. 

The shortest participant response times was for 

arrow designs 1 and 3 at all locations across all signs 

(figure 16). Participants had the longest response time 

for arrow design 4 for all locations. No other pattern was 

observed for the other four sign configurations.

Average Response Times for Different Signs

Figure 17 shows average response times corresponding 

to each sign configuration, composed of all arrow 

designs and roadway geometries. Associated with the 

shortest response time at 1-mi, 0.5-mi, and exit locations 

was sign configuration 1. For the 1-mi location, sign 

configuration 4 prompted shorter participant responses 

than the other three sign configurations. The other 

three configurations prompted similar average response 

times. Assessment of statistical analysis revealed that 

for the 1-mi location, arrow designs had no statistically 

significant impact on participant response times 

(p = 0.196). However, sign configurations (p < 0.001), 

roadway geometries (p < 0.001), gender degrees of 

freedom (df) 1, p = 0.003), and age (p < 0.001) had 

significant impacts on participant response times. 

Interactions between arrow design (p = 0.039) and 

sign configurations, and arrow designs, and roadway 

geometries (p = 0.011) were statistically significant. The 

three-way interaction between sign configuration, arrow 

designs, and roadway geometries was also statistically 

significant (p = 0.001).

For the 0.5-mi location, sign configuration 4 had the 

longest response time. Participant response times were 

similar for the other three signs. At this sign location, 

arrow design had no statistical significance (p = 0.196) 

on response times. The impacts of sign configurations 

(p = 0.016), roadway geometries (p < 0.001), gender 

(p = 0.012), and age (p < 0.001) were statistically 

significant. The three-way interaction was statistically 

significant (p = 0.003) as well.

Regarding exit location, participant response time was 

longer for sign configuration 3 than for other signs. Sign 

configuration 2 had a shorter response time than the other 

alternate sign configurations. Response times for alternate 

sign configurations did not show a consistent trend at all 

locations of the signs. Evaluation showed that the impact 

of arrow design on response time was not statistically 

significant. In contrast, the impacts of sign configurations 

(p = 0.043) and roadway geometries (p < 0.001) on 

response times were statistically significant. Interaction 

between arrow designs and sign configurations also were 

significant (p = 0.003).

Based on the estimates from the GEE model, the main 

effect (sole effect of an independent variable) of sign 

configurations and roadway geometry was significant 
14

for all three locations. Table 1 shows the difference 

in response times relative to sign configuration 1 

(full-sized OAPL). Sign configuration 1 relates to 

the shortest participant response time at all three 

sign locations. Participant response times for sign 

configurations 1, 2, and 3 at the 1-mi location were 

not statistically different. The response times for 

sign configurations 2 and 3 were 0.9 and 1.18 s, 

respectively, higher than for sign configuration 1. At 

the 0.5 mi location, participant response times for sign 

configurations 1, 3, and 5 were not statistically different 

from each other. Response times for signs 3 and 5 were 

0.8 s higher than for sign configuration 1. Response times 

for all the signs were statistically different from each 

other at the exit location. Table 1 shows signs participant 

response times from lower to higher times.

This study found that the main effect of roadway 

geometries was statistically significant at a 95 percent 

confidence level (p = 0.05). Single-exit geometry 

had lower response times than dual-exit geometries 

for all sign locations. However, impact of interaction 

between sign configurations and roadway geometry on 

participant response time was statistically significant. 

At the 1-mi location, signs 2, 5, and 4 had lower 

response times than did sign configuration 1 for roadway 

geometry 4. Participant response times for those signs 

were, respectively, 1.7 s (p = 0.021 s), 2.4 s (p < 0.001), 

and 2.1 s (p = 0.029) shorter than for sign configuration 1. 

On roadway geometry 2, sign configuration 2 had a 0.9-s 

(p = 0.047) shorter participant response time than sign 

configuration 1 at the exit location. Participant response 

times for sign configuration 2 was better for roadway 

geometries 2 and 3 as well.

Figure 17. Graph. Average response times corresponding to each sign configuration.

Source: FHWA.

Table 1. Sign configurations’ ranking based on response 

times from shortest to longest.

1 Mi 0.5 Mi Exit

1, 2, 3* 1, 3, 5 1

4 4 5

5 2 3

— — 2

— — 4

— = No entry.

*The differences between sign configurations placed on the same line 

were not statistically significant.
15

Figure 18. Graph. Average percent accuracy of lane choice based on destinations.

Source: FHWA.

Response Accuracy 

Participants received questions about the lanes to use to 

go to the destinations shown on the signs. This part of 

the study assessed the impact of sign location and sign 

configuration on the accuracy of participants’ responses. 

Average accuracies corresponding to different destinations 

were calculated at different sign locations from the exit. 

Figure 18 shows the results of participants’ average percent 

accuracy to signs placed at 1 mi from the exit, 0.5 mi from 

the exit, and at exit locations. For Dallas—the through 

destination—participants’ responses to sign configuration 1 

were approximately 20 percent higher than participants’ 

responses to the other four sign configurations. For Plano 

and Waco, accuracies among the sign configurations 

showed mixed results, i.e., no distinct pattern of accuracy 

was noticed among sign configurations. Accuracies were 

higher for Plano than Dallas and Waco.

Accuracies for lane type were calculated based on the 

answers for destinations questions. Through lanes were 

defined as lanes that allow traffic moving only straight 

ahead. In this experimental setup, through lanes were 

the two far-left lanes. The option lane, the second lane 

from the right, was the lane that allowed bidirectional 

Figure 19. Illustration. Lane assignment categories 

in full-sized OAPL.

Source: FHWA.

movement—straight ahead or right exit. The exit lane was 

the lane that took participants to only the exit destination, 

the far-right lane. Figure 19 shows the through option and 

exit lanes. 
16

Average Accuracy Time for Different 

Roadway Geometry

Figure 20 shows participants’ average lane selection 

accuracy over different roadway geometries and arrow 

designs. Specifically, the graph presents sign-selection 

accuracy for a sign positioned 1 mi from the gore for the 

five sign configurations over four roadway geometries. 

In general, selection accuracy for through and exit lanes 

was higher than for the option lane. On most roadway 

geometries, participants responded to sign configuration 1 

with greater accuracy than for through and option lanes. 

For exit lanes, no discerning selection accuracy pattern 

could be observed. Similar comparisons were made 

among participant selection accuracies for different 

sign configurations at 0.5 mi and exit locations. Sign 

configuration 1 had higher selection accuracy than did the 

other sign configurations for most sign locations. Selection 

accuracies for through and exit lanes were higher for 

roadway geometries 1 and 4 than for roadway geometries 2 

and 3. Accuracies associated with option lanes were low at 

all sign locations.

Figure 20. Graph. Response accuracy of sign configurations over roadway geometries.

Source: FHWA.

Average Accuracy Time for Different 

Arrow Designs

Similarly, accuracies of response times to different sign 

configurations were compared over different arrow designs. 

Figure 21 presents lane selection accuracies for different 

arrow designs from gore. Selection accuracy for sign 

configuration 1 was higher for all the arrow designs. Option 

lane accuracy was consistently lower or through and exit 

lanes. Alternate sign configurations (2, 3, and 4) displayed 

inconsistent patterns for all sign locations. Lane selection 

accuracy for sign configuration 1 was higher for option 

lanes across all arrow designs.

Sign configurations were compared by averaging 

accuracies across arrow designs and roadway geometries. 

Figure 22 shows lane selection accuracy for sign 

configuration 1 garnered slightly higher accuracy 

percentages for through and option lanes. Exit lane 

accuracies were similar for all the signs. Option lane 

accuracies were low for all three sign locations.
17

Figure 21. Graph. Response accuracy of sign configurations over arrow designs.

Figure 22. Graph. Average percent accuracy based on sign configurations.

Source: FHWA.

Source: FHWA.
18

The research team used GEE models to evaluate the 

statistical significance of the independent variables and 

found a 95 percent confidence level. Sign configurations 

and roadway geometries were statistically significant at 

1- and 0.5-mi sign locations. Selection accuracy for the 

exit location was not statistically significant.

Table 2 summarizes the statistics regarding the 

significance of the independent variables (sign 

configurations, arrow designs, and roadway geometries).

In table 3, the order of sign configurations is from most 

to least likely to elicit an accurate lane selection response. 

Analysis of main effects of the sign configuration 

produced this order. Analysis of selection accuracies 

for different types of lanes occurred separately. 

More than one sign configuration on the same line 

indicates no statistical difference in lane selection 

accuracies between the configurations. For example, 

at the 1-mi sign location, sign configurations 1 and 2 

were not found statistically different from each other 

regarding selection accuracy. The likelihood of sign 

configuration 5 eliciting accurate responses was lower 

than for sign configurations 1 and 2 for through lanes. 

For through lanes, sign configurations 1, 2 and 5 had 

higher likelihood than 3 and 4. For option and exit lane 

accuracies, no such pattern could be observed.

Table 2. Statistical significance of independent variables.

Sign 

Location

Statistical 

Features

Sign Configuration Roadway Geometry

Through 

Lanes

Option 

Lane

Exit 

Lane

Through 

Lanes

Option 

Lane

Exit 

Lane

1 mi

df 4 4 4 3 3 3

χ2 37 53 2.62 80.1 461 7.38

p-Value <0.001 <0.001 0.621 <0.001 <0.001 0.061

1⁄2 mi

df 4 4 4 3 3 3

χ2 16 25.7 8.97 86 268.9 2.93

p-Value 0.003 <0.001 0.062 <0.001 <0.001 0.403

At exit

df 4 4 4 3 3 3

χ2 40 27 10.4 74.8 327 9.36

p-Value <0.001 0.034 <0.001 <0.001 <0.001 0.025
19

Table 3. Order of the sign configuration based on their accuracies and statistical significance.

Lane 

Types 1 Mi 0.5 Mi Exit

Through 

lanes

1, 2 1 1

5 2 5

4 5 2

3 3 3

‒ 4 4

Option 

lanes 

1 1,3 1, 4

3, 4 2 5

2 4 2

5 5 3

Exit 

lanes 1, 2, 3, 4, 5 1, 2, 3, 4, 5

1, 2

5

4

3

Note: The differences between sign configurations placed on same line were not found statistically significant.

Confidence of Answers

After responding to the questions about the appropriate 

lane choice for different destinations, participants rated 

confidence in their answers. The basis for calculating 

the average rate was their responses over roadway 

geometries and arrow designs. Using GEE models, 

researchers evaluated the sign configurations more 

likely to receive high confidence ratings. Table 4

shows average ratings of the sign configurations. 

Sign configuration 1 received the highest confidence 

ratings for all sign locations. Sign configurations 

2 and 5 received higher confidence ratings than 

configurations 3 and 4. The statistical analysis, as well 

as the sign order in table 4, reflects this confidence 

level. Statistical analysis revealed that for the 0.5-mi 

sign location, sign configurations 2 and 5 were likely 

to have higher ratings than sign configurations 3 and 4. 

Sign configurations 2 and 5 did not have a statistically 

significant difference. Similarly, rating results for sign 

configurations at exit location were not statistically 

significant. Also, accuracy responses for sign 

configurations 3 and 4 were not statistically different.
20

Table 4. Confidence ratings of sign configurations.

1 Mi 0.5 Mi Exit

Sign 

Configurations Ratings Sign Configurations Ratings Sign Configurations Ratings

1 4.5 1 4.5 1 4.5

2 4.3 2 4.3 2 4.4 

3 4.1 3 4.2 3 4.2 

4 4.2 4 4.1 4 4.2

5 4.3 5 4.3 5 4.3

The confidence ratings mirrored the accuracies for 

through lanes. Both accuracy and confidence ratings 

for sign configurations 2 and 5 were higher than for 

sign configurations 3 and 4. However, accuracies for 

option and exit lanes did not reflect this observation. 

It is worth noting that even though there are statistical 

differences between the confidence ratings of the signs, 

the ratings remained between 4.1 and 4.5.

Effectiveness of Sign Configurations

Participants also rated how effective each sign was at 

conveying the specific lane assignment information 

following the method demonstrated in figure 14. Sign 

configuration 1 received an effectiveness rating of 

4.0 out of 5.0. Sign configurations 2 and 5 received 

ratings 3.9 and 3.7, respectively. Participants rated sign 

configurations 3 and 4 as 3.6 each out of 4.0.

Comparisons of Arrow Designs

Researchers used two methods to assess arrow designs: 

by actual differences in response times and accuracies 

and by participants’ perceived effectiveness of the 

arrow designs used in a sign configuration. Arrow 

designs impacted response times significantly but did 

not impact response accuracy. Responses times for 

arrow designs 1 and 3 were statistically no different, 

and both were shorter that response times for arrow 

designs 2 and 4.

Participants also rated arrow designs for their 

effectiveness as part of a sign. Their design preferences 

did not match their response time results. Participants 

preferred arrow design 2, followed by designs 1, 

4, and 3.

CONCLUSION AND RECOMMENDATION 

This study evaluated the effectiveness of alternates to 

OAPL signs for different roadway geometries. It also 

evaluated the effectiveness of four different arrow designs 

and layouts used on the signs. The researchers used four 

dependent variables to study drivers’ perception and 

comprehension of the signs: response time (how long it 

takes to understand the message of the sign), response 

accuracy (how accurately the participant interpreted the 

message about the lane choice of the sign), participants’ 

confidence in their answers, and perceived effectiveness 

of the signs using ratings (how effective participants 

thought a sign was in indicating lane assignments). 

Independent variable (effectiveness of the arrow designs 

was also assessed).

Response times across the sign configurations were 

higher at the 1-mi sign location than at the 1⁄2-mi and exit 

sign locations. When the average response times were 

aggregated across different roadway geometries and arrow 

designs, the participants understood sign configuration 1 

at the 1 mi location most quickly.

However, study findings indicate taking caution if 

considering the use of sign configuration 1 on roadway 

geometry 4 (dual-lane exit with option lane followed by 

downstream dual-lane exit with option lane). This is to 

note that sign configuration 1 is not MUTCD compliant 

for roadway geometries with multiple closely spaced 

exits. The reason is that roadway geometry 4 includes 

alternate sign configurations that had shorter response 

times than did sign configuration 1. Participant response 

times for sign configuration 2 differed from times for sign 
21

configuration 3; however, both times did not statistically 

differ from times for sign configuration 1.

Participants recorded the longest response times for 

sign configuration 5 (2.1 s longer than response time 

for sign configuration 1). The findings from response 

times indicated that the OAPL, partial-width OAPL 

with pull-through sign, and partial-width OAPL without 

pull through sign have some advantage over other 

sign configurations. For OAPL with pull through sign 

(sign configurations 2 and 5), a vertical separator was 

advantageous. However, for a partial-width OAPL 

(sign configurations 3 and 4), not having the vertical 

separator presented an advantage. An explanation for 

this difference may be that sign configurations 1, 2, 

and 5 present more information than information in 

sign configurations 3 and 4. The vertical separator may 

facilitate quick understanding of the information by 

providing a visual barrier between different segments of 

information. For sign configurations 3 and 4, a vertical 

separator may not have an importance.

In contrast, at the 1⁄2-mi sign location, sign configuration 5 

was more effective than sign configuration 2. At that 

location, sign configurations 3 and 5 were found to 

be statistically insignificant from sign configuration 

1 with the shortest response times. In this case, sign 

configuration 2 had the longest response time (1.3 s 

longer than sign configuration 1).

At the exit location of the sign, sign configuration 1 

had the shortest response times followed by sign 

configuration 5 (1 s longer) and configuration 3 

(1.1 s longer). Locations of the sign seemed to play an 

important role in variation in response times among 

sign configurations. Considering all the sign locations 

sign configuration 3 (partial-width arrow-per-lane 

without vertical separator or pull-through) was the 

most similar, meaning, prompted response times were 

very close to those recorded for sign configuration 1 

(full-sized OAPL).

Descriptive statistics of response accuracy (lane choice 

accuracy) revealed that none of the signs conveyed 

option lane information as effectively as they conveyed 

information for through lanes and exit lanes. Sign 

configuration 1 had higher accuracy (95 percent at 

1 mi, 93.3 percent at 0.5 mi, and 91.4 percent at the exit 

location of the sign) than the other sign configurations 

(figure 22). Overall, lane selection accuracies were 

higher when participants saw the sign 1 mi ahead of the 

exit than when sighted at a 0.5-mi and exit locations. It 

should be noted that at the 1 mi sign location, response 

times were longer than at other locations.

Sign configurations 2 and 5 (partial-width arrow-per-lane 

with and without vertical separator with pull-through 

sign) had higher accuracy than sign configurations 3 

and 4 (partial-width arrow-per-lane with or without 

vertical separator or pull-through) for through lanes. An 

explanation for these differences could be that in the 

partial-width sign configurations without the pull-through 

sign (3 and 4), explicit information about the through 

destination was not provided. When participants were 

asked about the locations they have not seen in the 

sign (e.g., Dallas), the accuracy for through lanes was 

negatively impacted.

However, sign configurations 3 and 4 had higher lane 

choice accuracy than did sign configurations 2 and 5. 

Conveying option lane information is complicated. 

Partial-width sign configurations showing less information 

may contribute to the higher accuracy of option lane 

choice. If placing full-sized OAPL is not feasible, sign 

configurations 3 and 4 could be advantageous for agencies 

targeting a specific segment of the roadway where vehicle 

weaving movement in the option lane is a major concern. 

Although, this should be taken into consideration that sign 

configurations 3 and 4 are not MUTCD compliant and 

would need to go through the MUTCD Experimentation 

Process. Exit lane choice accuracy was similar between 

sign configurations 3 and 4, ranging from 94.8 to 93.3 

percent among the sign configurations at three locations.

Confidence ratings regarding lane choice questions 

revealed that sign configuration 1 received the highest 

confidence, followed by sign configurations 2 and 5. A 

potential reason for sign configuration’s high rating may 

be that these three sign configurations had information 

about all destinations. Sign configurations 3 and 4 ranked 

lower than sign configurations 1, 2, and 5; however, the 

rating scores remained between 4.1 and 4.5. Confidence 

in sign configurations 2 and 5 reflected the lane choice 

accuracies for those signs for through lanes. For option 

and exit lanes, there was no observable trend. Participants’ 

preference for sign configurations 2 and 5, over 3 and 

4, positively impacted effectiveness ratings for sign 

configurations 2 and 5.

Arrow design 1 was associated with lower preference and 

higher effectiveness ratings than alternate designs except 

for arrow design 3. Arrow design 3 is recommended as 

well as arrow design 1.

Although there is wide variation in the research findings, 

participants felt more confident in their lane selections 

and found it helpful to have information about all the 

destinations (sign configurations 1, 2, and 5). However, 

assessment of the time it took to comprehend the sign 

(response time) and lane choice accuracy (response 
22

Further research could be conducted on simulated urban 

and rural roadways to test complexity of destination 

names (different length of the word can have different 

impact on sign comprehension), varying lettering and 

shield sizes, incorporation of various sign spacing 

between exits, volumes of traffic, number of lanes, 

etc. Additionally, testing could be expanded to test the 

effectiveness of signs in contrasting environments. Those 

tests would be helpful in producing recommendations for 

a wide variety of the agencies.

APPENDIX

The appendix displays different levels of the three 

independent variables that were used to produce different 

experimental scenarios. There were 5 sign configurations 

(1–5) those had separate versions for 4 different arrow 

sizes. These sign configurations with different arrow 

designs were, further, applied to different roadway 

geometries (1–4) to evaluate participants’ comprehension 

and perception as shown in table 5.

accuracy) did not translate to participant preference 

in some cases. For example, participants did not find 

sign configurations 3 and 4 to be highly effective in 

conveying information about the lanes, but their lane 

choice accuracy was high for these sign configurations. 

There is the possibility that based on sign location and 

the goal the agency has for the sign may make sign 

configurations 2, 3, and 5 viable options, if using a 

full-sized OAPL is not feasible. Researchers of this 

study would like to reiterate that sign configurations 2, 

3 and 5 are not compliant with current MUTCD 

guidelines and would need to go through the MUTCD 

Experimentation Process.

There is a clear tradeoff between cost and performance 

of sign configurations. Sign configuration 1 (full-sized 

OAPL) is the most effective in both response time and 

lane selection accuracy, but it is expensive. Findings 

of this study indicate the potential for using other sign 

configurations for specific locations and scenarios.

Table 5. Experimental scenarios.

Roadway 

Geometries

Sign 

Configurations

Arrow Designs

1 (1,0,0) 2 (2,0,0) 3 (3,0,0) 4 (4,0,0)

1 (0,0,1)

1 (0,1,0) (1,1,1) (2,1,1) (3,1,1) (4,1,1)

2 (0,2,0) (1,2,1) (2,2,1) (3,2,1) (4,2,1)

3 (0,3,0) (1,3,1) (2,3,1) (3,3,1) (4,3,1)

4 (0,4,0) (1,4,1) (2,4,1) (3,4,1) (4,4,1)

5 (0,5,0) (1,5,1) (2,5,1) (3,5,1) (4,5,1)

2 (0,0,2)

1 (0,1,0) (1,1,2) (2,1,2) (3,1,2) (4,1,2)

2 (0,2,0) (1,2,2) (2,2,2) (3,2,2) (4,2,2)

3 (0,3,0) (1,3,2) (2,3,2) (3,3,2) (4,3,2)

4 (0,4,0) (1,4,2) (2,4,2) (3,4,2) (4,4,2)

5 (0,5,0) (1,5,2) (2,5,2) (3,5,2) (4,5,2)
23

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Table 5. Experimental scenarios. (Continued)

Roadway 

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Sign 

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Arrow Designs

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24

Researchers—This study was performed by these researchers at Leidos, Inc.: Ananna Ahmed (ORCID: 0000-

0002-5353-508X), Starla Weaver (ORCID: 0000-0002-9559-8337), Szu-Fu Chao (ORCID: 0000-0002-2037-5200), 

Mathew Marchese (ORCID: 0000-0002-6899-8810).

Distribution—This TechBrief is being distributed according to a standard distribution. Direct distribution is being 

made to FHWA divisions and Resource Center.

Availability—This TechBrief may be obtained at https://highways.dot.gov/research.

Key Words—Overhead arrow-per-lane guide sign, partial-width OAPL guide sign, sign configuration, arrow size, 

sign comprehension, response time, lane choice, sign preference, lane selection accuracy.

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 Extended TechBrief 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.

MARCH 2023 FHWA-HRT-23-036

HRSO-20/03-23(WEB)E

Recommended citation: Federal Highway Administration, 

Evaluation of Additional Alternatives of, and Arrow Sizes for, Overhead 

Arrow-per-Lane Guide Signs (Washington, DC: 2023) https://doi.org/10.21949/1521980

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November 24, 2020.

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Devices. 2012b. GMI Signs and Technical Committee 

Recommendation Meeting Minutes, January 19, 2012, 

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last accessed November 24, 2020. 

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