Evaluation of Errors in Road Signs in a Long Roadwork Zone Using a Naturalistic Driving Study

Abstract

The paper presents an application of a new, simple approach for the naturalistic assessment of road sign quality from a driver’s perspective, using dashboard camera recordings. This method was used to evaluate signage along a 69.6 km road construction zone in Poland associated with the phased upgrade of a dual carriageway with unlimited access into a motorway. The analysis focused on three distinct phases of the roadwork: the beginning of roadwork, the progress of roadwork, and finishing roadwork. The correctness, visibility, and quality of the road signs were assessed on a specially developed scale. The study found that 1135 road signs were unnecessary, which was equal to 36% of all signs. The majority of all signs (48.1%) indicated prohibition: more than one third (33.6%) of them were speed limit signs, of which 52% were posted without the need. It was demonstrated that the simple method applied in this study can be considered a useful tool to identify deficiencies in signage, which could ultimately improve road safety and make road management more sustainable. Moreover, this study confirmed again that the use of appropriate video recordings makes it faster and easier to conduct an inventory of road signs.

1. Introduction

The main role of all road signs is to guide drivers on how and where to move safely along the roadway. Traffic devices are divided into two types: road signs and road markings. Signs warn of hazards and show which route to follow to keep traffic flowing. The implementation of a coherent signage system and the application of logical traffic organization principles are crucial. Ideally, the traffic organization should be defined in such a way that every road user knows how to move, even without road signs [1,2]. For road signs to be helpful to drivers, they must be positioned correctly and clearly visible [3]. In order for road signs to always be in good condition, they must be regularly checked [4]. Such an assessment can be made during road trips according to a special assessment scale [5,6].

In the context of traffic sign placement and design, both national and international regulations are crucial to maintain consistency and ensure road safety. One of the most important international agreements is the Vienna Convention on Road Signs and Signals developed in 1968 [7], which sets out global standards for road signage and symbols. This convention mandates the use of standardized traffic signs to facilitate navigation on international roads and ensure their clear understanding by road users across different countries. It outlines rules regarding the shapes, colors, and dimensions of signs, which are essential for driver safety and orientation. In Poland, these international regulations are integrated into national law. The Act on Road Traffic of 20 June 1997, together with appropriate legal notices of the Minister of Infrastructure [8,9], incorporates these standards and provides specific guidelines to design and position traffic signs, ensuring alignment with European Union regulations. Similarly, in the United States, the Manual on Uniform Traffic Control Devices (MUTCD) [10], developed by the Federal Highway Administration, plays a critical role in standardizing the design and placement of traffic signs. The MUTCD specifies detailed rules on the shape, color, size, and placement of signs to ensure that they are visible and legible under various conditions, ultimately enhancing road safety. Both international agreements and national regulations play a fundamental role in maintaining road safety by providing clear, consistent, and easily understood traffic signs, regardless of location. These standards help to minimize confusion among road users and promote safer driving environments worldwide.

Whereas road safety audits can provide comprehensive and quite exhaustive information and pinpoint deficiencies [11], they can also be expensive and time-consuming. In addition, safety audits require the presence of the analyzing crew on site, which might affect the behavior of the drivers or obstruct the traffic. Thus, in this article, a new and expedient method to evaluate road features from the perspective of a driver is considered. It should also be added here that analysis of recording from a readily available dashboard camcorder is seen as an inexpensive, simple, and non-obstructive approach [12].

It is worth mentioning that there are road safety inspections in Poland as well as in other European countries [13,14]. Among different elements, the Polish guidelines also include control of road signs. Here, it should be pointed out that this part organizes in a very general way, requiring only the determination of whether one of following faults on an inspected road is present or not: a lack of signs, unnecessary signs, damaged signs, incorrect location of signs. However, a summary of the most common defects also incorporates mutually contradictory road signs and signs limiting visibility. Beside such declarations of problems, no further detailed separate assessment of each case is envisaged [15].

The specificity of the considered approach lies in its ability to capture real-world driving experiences, focusing on the natural interactions between road users and infrastructure elements. By avoiding artificial or staged scenarios, it provides a genuine understanding of the challenges drivers face, offering practical insights into areas where road safety and infrastructure can be improved. All these principles align closely with the foundational concepts of naturalistic driving studies (NDS) [16], which are the basis of the discussed method here.

NDS is a very valuable method for the analysis of road users’ behavior and assessment of elements of road infrastructure [16,17]. Given the utility of NDS, it is quite surprising that it has not been employed so far for analyses of road construction zones, except for minor assessment [18,19,20]. These studies envisaged that NDS would provide a new perspective and would permit pinpointing some of the issues associated with road safety from the perspective of a driver traveling through a long work construction zone, observing deficiencies in roadside infrastructure, including road signs.

Driving in a roadwork zone can be associated with many dangers caused by the changed traffic organization [21]. Roadwork zones belong to areas where increased caution is required [18]. In order for the driver to be better prepared for an unusual event on the road, signs should be used, including those warning about impending danger (the driver can expect a given danger in advance and prepare to react) or limiting the speed limit (lowering the speed increases the time available for reaction during an unexpected traffic incident). Temporary signs play an important role in the passive protection of vehicles, passengers, workers, and construction site equipment, as they are used to signal work zones [22]. Accordingly, it is fundamental to consider whether they are easy to read.

It should be remembered that the effectiveness of labeling is related to the “priming effect,” an ergonomic paradigm based on the anticipation of some information (stimulus) that would influence the response to the next stimulus [23]. In this regard, the presence of warning signs informs the driver of upcoming work sites and prepares him to take appropriate action before reaching the hazard. Several studies have shown that earlier warning enables people to react more quickly, resulting in more correct driving behavior [24]. There is a study supporting the theory that unconsciously perceived signs (i.e., signs that drivers do not later recall) are also effective in reducing speed because they subconsciously alert drivers to hazards [25].

Proper location of road signs helps drivers avoid the problem of not being warned about the potential negative effects, which is especially important when driving through roadwork zones. Studies on the placement of signs have confirmed that it plays a key role because it affects the driver’s perception—reaction time and speed [3]. However, minimizing the number of signs through elements of road infrastructure is one of the effective ways to organize traffic and improve safety, because too many of them causes distraction [26].

The objective of this study was to extend and verify a previously developed approach to assess the quality, visibility, and correctness of road signs based on the NDS principles. The assessment method is presented using the example of a long roadwork zone. The analysis was carried out during the major reconstruction of the main north–south road in Poland; this appears to be the first reported assessment of this kind. Evaluation was done based on recordings from the dashboard camcorder of a vehicle driven by one person, which limited the additional complexity associated with numerous driving styles. Preliminary results of this research were already presented [5]. This study has been expanded while including journeys at various stages of road construction, and the assessment scale presented in the previous research work has been modified by improving the range of rating grades. The presented outcome would be useful not only for road safety scientists and advocates, but also for road administrators.

2. Methodological Aspects

2.1. Test Field

The road section being assessed concerns a roadwork zone along a 69.6 km stretch of the main north–south highway in Poland, national route 1, between the future interchanges of Piotrków Trybunalski Południe and Częstochowa Północ, encompassing two traffic lanes in each direction. This section of road underwent a complete reconstruction and upgrade, transforming from a dual carriageway unrestricted four-lane road (with a speed limit of 100 km/h, reduced to 70 km/h near intersections) to a six-lane motorway with a speed limit of 140 km/h. Throughout the construction process, the road was temporarily narrowed to three lanes (occasionally on short distances to two lanes).

To assess the impact of these changes on road sign quality and layout, the driver made trips at different stages of the road construction: at the beginning of the roadwork (when the entire section was under construction with frequent lane layout changes), during the progress of roadwork, and at the finishing of the roadwork (when parts of the new road were opened to traffic). The trips were conducted in both directions. In some cases, the test driver opted for alternate routes when traffic congestion was significant. As a result, the analysis was conducted only on specific sections, and these partial drives were included in the total distance covered rather than being considered separately. To eliminate the impact of incomplete drives, all results in this study were recalculated per 1 km driven for each of the three stages of roadwork. In total, 343.3 km were driven, providing a comprehensive dataset for evaluating the roadwork zone.

2.2. Equipment

Data collection was conducted using a dashboard camcorder that recorded video at a rate of 30 frames per second, with a resolution of 1920 × 1080 pixels and a field of view of 140°. Such a wide camera angle allowed covering all necessary points of interest within the scope of the road and its surroundings, which is required to collect all necessary information. The camcorder was equipped with a Global Positioning System (GPS) receiver, which captured information at a frequency of 1 Hz and saved it in NMEA file format, a standard format developed by the National Marine Electronics Association (NMEA).

Throughout the entire process of data collection and analysis, strict adherence was maintained to the ethical and data protection guidelines established by Politechnika Krakowska and Palacký University Olomouc. Only anonymized averages have been presented, and all necessary precautions were taken to prevent the disclosure of any information that could potentially violate privacy rights. It is important to note that there are no legal restrictions in Poland regarding such recordings.

2.3. Data Processing

As part of this research work, based on the observation of video recordings, each sign was recorded and described with basic information: date; time; location on the left, right, or both sides of the road; and number of signs divided by type or description in the case of complementary plaque. If a road sign contained a plaque, it was assessed as a whole. Evaluation of road signs for correctness, visibility, and quality was done based on a self-devised scale 0–2–5–10, which is described in

Table 1. Modified assessment scale for road signs.

Rating	Correctness	Visibility	Quality of Sign Face
0	Appropriate, compliant with regulations	Good, no obstructions	Good, clearly legible
2	Counterintuitive, information unclear, might cause confusions: no repetition on the left side of the road, a sign is not aligned, but its meaning and purpose are clear	Poorly positioned, probability of being unnoticed, spaced inappropriately: a sign is tilted, crooked, installed too late, or too close to another sign, but still legible and understandable	Adequate, quality not affecting overall visibility or legibility, but improvement necessary: a sign is dirty, damaged, or bent, but still legible and understandable
5	Erroneous or inappropriate, confusing: a sign is turned or installed incorrectly, contrary to the regulations (e.g., too low), but visible, the same sign is repeated—unnecessary, but consistent with each other	Positioned incorrectly, blending with similarly colored background, irrelevant (e.g., no longer valid sign), tilted or lying on the ground, poorly/slightly visible, with unreadable content	Damaged, poor quality, but still might be perceived at some angles and in some circumstances: a sign is partially faded, partially dirty, or partially bent in a way that may limit its visibility
10	Missing or plainly erroneous road sign: missing an important sign, a contradictory sign causing incorrect driver behaviour, mutually exclusive signs, a sign installed inconsistently with regulations and incomprehensible	Obscured or invisible, positioned sideways: an important (valid) sign on the ground, a broken sign, obscured by another sign or vegetation in a way that prevents its visibility and understanding	Missing or not legible, erroneous: a sign is faded, damaged, bent, preventing its visibility and understanding, the absence of a sign in an obvious situation

: on the one hand, these details give an opportunity for everyone to repeat such a field study in a similar way, and on the other hand, they allow for avoidance/minimization of the subjectivity when making the assessment. With reference to the scale from the earlier work [5,6], in this study, to increase the error significance, the scale for road signs was reversed, and the values for errors were strengthened.

Any noticed errors, inconsistencies, uncertainties, visibility obstructions, and redundancies amongst road signs were crosschecked for coherence with other signs and road features. Furthermore, unnecessary signs (e.g., unjustified repetitions) were counted. Data processing was done with an open-source video editing software (VSDC Free Video Editor version 8.1.1.450).

3. Results

An inventory of road signs for driving in both directions along the entire section was conducted across the three analyzed stages of construction, as shown in

Table 2. Road signs—evolution of their number and rating.

Period	Beginning of Roadworks	Progress of Roadworks	Finishing Roadworks
Distance [km]	84.2 (24.5%)	128.3 (37.4%)	130.8 (38.1%)
Distance [min]	76.2 (24.4%)	120.7 (38.7%)	115.0 (36.9%)
Number of signs	927 (29.3%)	878 (27.7%)	1360 (43.0%)
Number of signs per 1 km	11.0	6.8	10.4
Number of posts	517 (28.7%)	552 (30.7%)	730 (40.6%)
Number of posts per 1 km	6.1	4.3	5.6
Number of signs on the left side 1	290 (29.3%)	242 (24.4%)	459 (46.3%)
Number of signs on the left side per 1 km	3.4	1.9	3.5
Number of posts on the left side	132 (28.8%)	129 (28.1%)	198 (43.1%)
Number of posts on the left side per 1 km	1.6	1.0	1.5
Signs supplemented with complementary plaques	143 (24.6%)	207 (35.6%)	232 (39.8%)
Signs supplemented with complementary plaques per 1 km	1.7	1.6	1.8
Number of intersections	6 (35.3%)	6 (35.3%)	5 (29.4%)
Number of signs per intersection	154.5	146.3	272.0
Number of signs per 1 min of driving at the posted speed limit	3.0	2.8	4.4
Average rating 0-2-5-10	0.50	0.53	0.66
-correctness	1.22	1.40	1.63
-visibility	0.13	0.08	0.15
-quality	0.15	0.10	0.21
Low ratings 2 (5 and 10)	10 (25.6%)	10 (25.6%)	19 (48.8%)
Plainly erroneous	49 (73.1%)	4 (6.0%)	14 (20.9%)
Unnecessary 3	183 (16.1%)	347 (30.6%)	605 (53.3%)

¹ Including the repeats. ² Low ratings simultaneously for all three parameters. ³ Not needed based on road features—assessment based on the recordings.

as well as in Figure 1. The number of road signs, posts, and plaques was assessed. Additionally, travel distance and time were taken into account. The results were converted into 1 km driven for each of the three stages of roadwork. Moreover, calculations were also performed per intersection, given the large number of signs that, according to regulations, are invalidated by intersections (e.g., speed limit signs). In addition to the assessment, special attention was paid to plainly erroneous (potentially misleading and leading to errors in traffic, dangerous) and unnecessary signs.

In order to check whether parameters presented in Table 2 differ significantly depending on roadwork stages, a basic statistical analysis was performed using Student’s t-test (one-tailed paired distribution) with a 5% significance level. First of all, two samples of five parameters were considered: (1) in absolute values and (2) per 1 km. The p-values for the first sample were 0.500 between the start and progress of roadworks, 0.240 between the start of roadworks and the end of roadworks, and 0.236 between the progress of roadworks and the end of roadworks. The results of p-values for the second sample were 0.228, 0.465, and 0.245, respectively. Taking into account that it is not possible to make claims about the truth of the null hypothesis on the basis of p-values only, an effect size analysis using Cohen’s d was also included to better understand the significance of changes between different phases of the construction work. For the first sample, the actual difference between the start and progress of roadworks is trivial, but when comparing the finishing roadwork stage with the start and progress stages, the effects were medium (Cohen’s d values are equal to 0.6 and 0.5, respectively). When considering the second sample, only the comparison of the progress of roadwork with the two other phases returned medium effects: 0.5 for both cases. Additionally, the significance of differences in correctness, visibility, and quality ratings was also examined and obtained, respectively: 0.482, 0.403, 0.425. The calculation of Cohen’s d values for ratings also confirmed trivial effects for all cases. Thus, although, according to the t-tests, relations between parameters did not change significantly for different roadwork stages, the effect sizes of t-tests were observed at a medium level for some cases.

Because no significant differences in parameters according to t-tests were found between the stages of roadworks and Cohen’s d values corresponded mainly to trivial and, only in some cases, medium effects, the subsequent results are presented collectively for all drives. Because no significant enough differences in parameters were found between the stages of roadworks, the subsequent results are presented collectively for all drives. However, it is important to note that the lack of significant differences is concerning because it was assumed that with the progress of the work, the number of signs would decrease, and their condition would improve, particularly at the end of data collection during the final stage of roadwork [27]: in the case of this study, while the number of signs decreased a bit during the progress phase of roadworks, it essentially increased when the finishing phase began, likely due to final adjustments and additions to the completed sections of the road. Moreover, the number of unnecessary signs grew permanently. All this raises questions about the effectiveness of the management and planning of the signage throughout the construction process, which is important to achieve operational, tactical, and strategical objectives of the road management and, as a consequence, make the whole system more sustainable [28]. As from stage to stage the total number of signs (especially unnecessary ones) and average rating values increased, this suggests a potential oversight in the systematic removal of unnecessary or outdated signs, which could compromise road safety. The expectation that conditions would improve as the work progressed underscores the importance of ongoing monitoring and assessment. Further investigation may be needed to determine the underlying causes of such a stagnation in sign quality and placement, ensuring that road safety standards are met as construction projects reach their completion.

A summary concerning the number of road signs divided by particular types together with their ratings is provided in

Table 3. Road signs—types and ratings (sum of the analyses from the six drives, three in each direction) ¹.

Type of Road Sign	All	Warning	Prohibitory 1	Prohibitory (Speed Limit) 4	Mandatory	Information	Direction	Construction	Other
Number of signs	3165	420 (13.3%)	1519 (48.1%)	510 (33.6%)	222 (7.0%)	42 (1.3%)	64 (2.0%)	112 (3.5%)	786 (24.8%)
Number of posts	1799	384 (21.3%)	991 (55.1%)	286 (28.9%)	218 (12.1%)	39 (2.2%)	47 (2.6%)	72 (4.0%)	48 (2.7%)
Repeats on the left side	921	67 (7.3%)	536 (58.1%)	279 (52.1%)	10 (1.1%)	7 (0.8%)	5 (0.5%)	33 (3.6%)	263 (28.6%)
Number on the left side 2	991	67 (6.8%)	545 (55.0%)	5 (0.9%)	66 (6.7%)	7 (0.7%)	5 (0.5%)	33 (3.3%)	268 (27.0%)
Number of posts on the left side	459	57 (12.4%)	299 (65.1%)	46 (15.4%)	65 (14.2%)	7 (1.5%)	5 (1.1%)	14 (3.1%)	12 (2.6%)
Supplemented with complementary plaques	582	260 (44.7%)	163 (28.0%)	21 (12.9%)	139 (23.9%)	1 (0.2%)	2 (0.3%)	16 (2.7%)	1 (0.2%)
Number per 1 km	9.2	1.2	4.4	1.5	0.6	0.1	0.2	0.3	2.3
Number per intersection	186.2	24.7	89.4	30.0	13.1	2.5	3.8	6.6	46.2
Number per 1 min of driving at posted speed limit	10.1	1.3	4.9	1.6	0.7	0.1	0.2	0.4	2.5
Average correctness rating	1.44	1.15	1.13	1.74	0.64	0.54	0.43	1.09	0.79
Incorrect (ratings 5 and 10)	39	5 (12.8%)	19 (48.7%)	12 (63.2%)	2 (5.1%)	1 (2.6%)	1 (2.6%)	2 (5.1%)	9 (23.1%)
Average visibility rating	0.12	0.10	0.08	0.16	0.06	0.06	0.02	0.48	0.06
Inadequate (ratings 5 and 10)	26	5 (19.2%)	10 (38.5%)	9 (90.0%)	1 (3.8%)	-	-	6 (23.1%)	4 (15.4%)
Average quality rating	0.16	0.08	0.15	0.27	0.06	0.06	0.10	0.51	0.10
Poor (ratings 5 and 10)	39	2 (5.1%)	21 (53.9%)	14 (66.7%)	-	-	2 (5.1%)	6 (15.4%)	8 (20.5%)
Plainly erroneous	67	2 (3.0%)	41 (61.2%)	23 (56.1%)	-	-	-	-	24 (35.8%)
Unnecessary 3	1135	7 (0.6%)	733 (64.6%)	381 (52.0%)	26 (2.3%)	-	-	2 (0.2%)	367 (32.3%)

¹ Including speed limit signs. ² Including the repeats. ³ Not needed based on road features—assessment based on the recordings. ⁴ Percentages from prohibition signs.

. This categorization of signs based on their function was done with the aim to identify areas where signage could be improved or updated to enhance driver awareness and safety. This detailed approach can provide valuable insights into the management of road signage during construction, which is crucial for maintaining safe and efficient traffic flow in changing environments. For example, for this study, the separation of speed limit signs from all prohibition signs confirmed that most unnecessary prohibition signs are associated with redundantly duplicated speed restrictions.

As the work progressed, the number of road signs and posts changed. The cause was not only a simple increase or reduction of their numbers. It can be also explained by the following reasons: locations of signs were changed (e.g., some signs from the same posts were into separate posts), some posts were left empty, etc. Obviously, there was a large increase in the number of signs in the final phase of roadwork, 53.3% of which were unnecessary. This phenomenon was due to the large number of situations where the signs on the sections were repeated when the new road was opened to traffic. Although the correctness, visibility, and quality of signs also deteriorated in the final stage (additional, often unnecessary signs were added to old and damaged ones), it should be pointed out that when looking at all the phases together, the road signs were of good quality (average rating was 0.16), even while many of them were positioned incorrectly (average rating was 1.44). The majority of signs (48.1%) indicated prohibition. More than one third (33.6%) of them were speed limit signs, of which 52% were posted unnecessarily.

The numbers are worrying: drivers cannot possibly perceive the road signs and at the same time focus on the road ahead while their perception is distracted by a road sign every 7.0 s. The largest encountered concentration of road signs was 14 signs (one of them on the left side) at a distance of 85 m—this situation is shown in Figure 2. Based on the study [29], which determined the average observation time of one road sign by the driver as 0.154 s, it can be concluded that drivers would need 2.156 s to observe the signs shown in Figure 2. Assuming that the driver respects the 60 km/h speed limit, in one second, they will travel 16.67 m, which means that 85 m will take only 5.099 s. However, the matter is complicated by the number of signs on one post: in one moment, the driver receives more information (e.g., two or three different signs placed one below the other) than from a single sign. In addition, the first upper prohibition sign B-6/8/9 “bicycles, tractors and horses are not allowed” has a triple meaning, which additionally requires more attention [30]. Such a situation confirms that research on the observation of such multi-meaning signs should be carried out.

Furthermore, the incorrect road signs are very concerning—drivers were misinformed about features such as distances to obstacles or the layout of the road ahead in 12 cases. Although such situations could be considered rare, taking into account the overall number of road signs, they undermine trust in road signs and leave drivers relying solely on their own perception and interpretation of the road features in front of them. An example of incorrectly placed signs that contradict each other and can mislead drivers (an informational sign shows the wrong road profile) and violate common sense (the speed limit applies over a stretch of only about 30 m, after which the speed is increased) is shown in Figure 3. Moreover, in several cases, incorrect signs forced drivers to break traffic regulations. As shown in Figure 4, the sign warning about lane change was placed after the lane change had occurred. At the same time, drivers were forced to cross a double solid line.

Additionally, the problem was a large number of unnecessary signs (as shown in Figure 5). The signs were placed only on the left side of the road, but they should have been on the right and only in such case their repeating on the left is acceptable. In addition, the third sign incorrectly shows the layout of the road lanes.

4. Discussion

Road signs should be uniform, intuitive, and fully legible for drivers [31]. Moreover, the number of messages sent to road users in the form of signs should be limited to the most important ones [26]. The analysis of road signs revealed not only their enormous excess but also a large number of signs falsely informing the drivers. Previous studies support this statement [5].

It is important to note that the driving occurred on different days of the week, under varying lighting conditions and weather. Unfavorable weather conditions, such as glare, rain, snow, and fog, could negatively affect the image quality of the video recordings, potentially leading to inaccuracies and errors in reading road signs. Additionally, the presence of construction vehicles and ongoing work could vary depending on the stage of construction, influencing road sign placement based on whether work was being carried out or whether workers were present on the road. However, this article does not examine these variables, as only trips conducted under clear weather conditions were selected for analysis. Here, it should be pointed out that such issues as, for example, the visibility of road signs during the winter months as well as the impact of other various disadvantageous weather conditions should be investigated separately and could be considered as further research directions of this topic. Similarly, tasks related to road markings were also excluded from consideration, mainly due to their specific nature and extensive coverage.

The study focuses on a single 69.6 km road construction zone in Poland, which may limit the generalizability of the results. The findings could have been more impactful if the study had been expanded by applying the method to different types of roads, urban settings, or international contexts, which, unfortunately, was out of the scope of this research work. A comparative analysis of signage deficiencies across different road environments and/or regions could provide a broader perspective on the issue, which should be considered as a further research direction.

The proposed scale for assessing road signs may require further refinements. For instance, it was observed that a road sign placed on a crooked post might be deemed as not meeting the quality requirement (because the law defines that a sign must be positioned straight) or the visibility requirement (because it is positioned improperly). These instances of uncertainty necessitate additional research and standardization for future assessments. Herein, the situation was classified as an issue with the visibility. Additionally, although the scale was benchmarked against existing international traffic safety standards and national regulations associated with road safety inspections, the involvement of independent reviewers or transportation professionals for its further validation should be considered as the next step to improve the discussed approach.

The regulations do not directly specify the maximum number of road signs that can be placed onto a kilometer of road, but they do so indirectly, specifying the minimum distances between them. For example, on roads with a maximum speed of more than 90 km/h, the minimum distance between signs is 50 m, on roads with a maximum speed of more than 60 km–20 m, and on other roads, the next sign may be placed at a distance of at least 10 m. At the same time, the regulations allow for placing up to three signs on one pole. Thus, it is easy to calculate that, theoretically, up to 300 signs can be crammed in one direction of travel per kilometer of road.

An additional problem for drivers is that different signs from the same group of types have different scopes of validity. Some of them create mutually exclusive combinations (for example, different road signs may be found on the left and right sides of the road), and the traffic regulations are so complicated that there are practically no drivers who would know the full meaning of all road signs that can be found on the road. For example, when it comes to the validity of prohibition signs in Poland, they apply along segments (i.e., until the occurrence of the next intersection). They can also be cancelled with other signs, e.g., the “end of prohibition” sign. However, if there are many signs and they provide different information, the driver may not know which sign is currently relevant.

The analysis confirmed a large number of road signs. One of these examples is the signs B-33 “speed limit 70 km/h.” On a section of only 25 km, 45 identical signs were placed. According to observations, 43 (95.6%) of them were repeated without a clear need (there was no cancellation or intersection). Such repeats can confuse the driver: “Is it only a repeat, or was there previously a different speed limit?” Furthermore, research suggests that while reminder signs, such as the “rappel” plates in France, play a role in increasing driver awareness, their effectiveness in reducing speed and improving road safety is limited without the support of additional measures [32].

The accumulation of road signs can lead to distraction, resulting in a failure to notice road signs [33], which may consequently lead to non-compliance with the speed limits normally imposed in roadwork zones. It is therefore important to organize the road signs as the work progresses and to keep them in good condition so that the traffic rules on the road are as clear and understandable as possible. Unfortunately, although they are written in the law, this study shows that road builders do not use the guidelines.

The range of signs used is constantly expanding, and unusual traffic situations require the use of non-standard signs or an unusual combination of existing standard signs. As a quite interesting special case, one can consider the road signs classified as construction signs, which should be easy to understand by any driver, but they lack a statutory regulation. These signs were often defined by road administrator, but one should note that this entity has no legal right to establish road signs; hence, they can be classified as unofficial—not existing according to the law. The question that remains open is whether drivers are required to obey a road sign that is not meeting the statutory demands.

It should be pointed out that this study did not investigate the underlying reasons for the excessive number of road signs or other issues, because its primary focus was to estimate the visibility, quality, and correctness of road signs using the proposed method. This approach aims to provide a practical evaluation of the current state of road signage, allowing the identification of problems and targeting future possible improvement actions and measures. Moreover, understanding the root causes of ineffective signage would require further analysis, including examining planning processes of roadworks, consulting with relevant authorities, and reviewing historical changes in regulations. Such an investigation would demand additional time and resources, which are beyond the scope of this study. While the research focused on the current situation, future studies could explore these systemic issues and offer recommendations for signage policy improvements.

Furthermore, the study did not include an analysis of driver reactions to inadequate signage, such as sudden braking or lane changes, and does not provide any direct proof for the statement that the elimination of unnecessary signage improves driver comprehension and safety, as it focused on the assessment of the quality, visibility, and correctness of road signs in a general context. Here, it is necessary to review that the primary objective was to extend and verify a previously developed approach, which identifies and assesses the presence of unnecessary, incorrect, or poorly placed signs, rather than directly measuring driver reactions. The study of driver behavior in the context of signage requires further analysis, for example, by using the eye-tracking technique and could be considered as a future research step. This would allow for a more detailed assessment of how drivers react to incorrect road signs, changes in road signage, etc. and, as a consequence, return outcomes, which help to better understand the impact of signage on driver behavior and ultimately lead to more precise recommendations to improve the road traffic safety.

5. Conclusions

Roadwork zones require special attention from the driver due to the large number of road signs. Moreover, as correctly positioned and clearly visible road signs are helpful for drivers, it could be concluded that road signs that are illegible or incorrectly placed can pose an unnecessary road safety risk. This article expands upon previous work by including journeys at different stages of road construction and introducing a new assessment scale. Each sign was registered along with an assessment of the visibility, quality, and correctness of the sign according to the modified assessment scale.

Observation of road infrastructure revealed the following: (1) road signs of good quality and visibility in most cases, (2) road signs that were falsely informing drivers, (3) an enormous excess of road signs with (4) plentiful unnecessary repeats, and (5) no removal of old signage as work progresses. The situation changed only when some sections of the road were partially put into use—then the signs were partially put in order, but some of them were still incorrect and unnecessary. The proposed simple method presented in this study should help identify signage gaps that could ultimately improve road safety.

This research is intended to serve as a guideline for road administrators and traffic managers to pay particular attention to the planning and subsequent monitoring of the installation of road signs, especially during multi-stage roadworks. In such cases, road signs often change with each phase of construction, which can create confusion among drivers. In addition, it is essential to highlight that all details associated with signage should already be addressed in the road design phase, including the proper placement and removal of road signs subject to road construction stages, which should further positively influence the whole road management system, making it more sustainable. Such proper management and early consideration of signage effectiveness at every stage should contribute to the creation of safer and more efficient roadwork zones.