Abstract
Supplemental traffic control devices (STCDs) help improve the safety of traffic controllers in work zones. Despite many forms of STCDs being developed and used in work zones, there is limited understanding available in the literature with respect to the barriers and motivators for greater use of STCDs as an alternative to human flaggers. This paper addresses this important gap by identifying the types of STCDs currently being used in the traffic management industry, along with the challenges and barriers limiting their broader adoption. The study methodology involved a two-step data collection process by engaging with 54 traffic control companies: first administering focus groups with representatives from 12 companies, followed by an online survey among representatives from 42 other companies. The study results revealed that while STCDs are generally used to improve safety, there is no consistent approach to guidelines, practices, or device selection nationwide. Key challenges identified by traffic control companies include the high cost of STCDs, insufficient training, and rapid technological advancements that sometimes lead to reliability issues. These factors can discourage the industry from using STCDs regularly. The study further identified that the industry would benefit from offering tax incentives, providing better training for traffic controllers, organizing workshops, and running awareness campaigns about new technologies to overcome these challenges. The study results can be used to outline improvements in standardization, training, and technological integration into the traffic management guidelines, which could promote the wider adoption of STCDs and enhance their effectiveness in managing roadwork safety.
Traffic controllers exposed to live traffic at road worksites are at significant risk of serious and sometimes fatal injury ( 1 , 2 ). The presence of a work zone is increases fatal and injury crashes by 33% ( 3 ). To minimize the risk of these crashes, supplemental traffic control devices (STCDs) are used in work zones around the world (e.g., [(1, 3, 4)]), providing safety for both workers and motorists. Portable barriers, as well as variable message signs (VMSs), are some of the most common STCDs used in work zones. A wide variety of STCDs are available for controlling traffic at work sites. The use of STCDs is mandatory in most work zones (5–7) around the world (exceptions apply where STCD use may not be practical or warranted). These include portable traffic lights (PTLs), portable boom barriers, VMSs, and so forth.
The STCD industry can be identified as a rapidly growing field where new technology is adopted to create innovative STCDs (e.g., [6, 8, 9]). Therefore, programs and organizations such as Austroads Innovative Temporary Traffic Management Device and Solution Assessment (AITDSA) in Australia, the National Highway Traffic Safety Administration (NHTSA) in the U.S.A., and National Highway Sector Schemes (NHSS) in the UK play a crucial role in guiding the STCD industry. Among these programs, the AITDSA stands out as it was launched in July 2022, in response to industry innovation and the evolution of temporary traffic management (TTM) technologies. This is a notable example of a program where new STCDs are reviewed and recommended for use by Austroads, and it identifies the Australian jurisdictions in which each specific device has been formally accepted for use. While these devices are not conceptually new, they each represent a refinement and innovative approach aimed at improving the safety, efficiency, and usability of devices. These can be seen as essential goals, the achievement of which should help to drive increased use of STCDs overall and greater consistency of use in TTM.
When further analyzing the Australian TTM guidelines, it was noted that a lack of information in these guides can result in a lack of knowledge among practitioners. As an example, even though a wide range of STCDs are in use at Australian work zones, the guidelines (e.g., [ 10 – 12 ]) only provide details of the PTLs and portable boom barrier. While information is available from international sources, particularly the U.S.A., such as the Manual on Uniform Traffic Control Devices (MUTCD), it may not be directly applicable to the Australian context because of differences in processes and guidelines in work zone traffic management. This lack of information on STCDs in the official guidelines means that the full potential of STCDs might not be used in Australian work zones and can contribute to the lack of knowledge among traffic control personnel on what devices are available to be used in different situations.
As a result of this lack of available information, improving the safety of roadworkers, especially human flaggers, has remained a key challenge for many jurisdictions. Human flaggers are identified as a high risk in work zones ( 13 , 14 ), and the need to replace these human flaggers has been established. However, human flaggers are still used extensively in work zones, as there is limited knowledge on human flagger alternatives available for practitioners to act on. A review of the literature, presented in the second section, further identified that there is limited understanding available with respect to the use of STCDs in work zones and the barriers and motivators for greater use of STCDs as an alternative to human flaggers. To fill this important gap in the literature, this paper aims to retrospectively review STCD use by the traffic control industry in Australia, analyze anecdotal evidence on STCD use, identify barriers to STCD use, and propose recommendations to increase STCD use in work zones. While this study presents a case study for Australian TTM, the methodology and findings of this study can inform similar research in other jurisdictions and have implications for understanding the barriers and motivators of STCD use in work zones.
Literature Review
As STCDs are used widely across the globe, this literature review explores existing research, government policies, and case studies to provide insights into best practices and potential areas for improvement. By assessing the effectiveness and limitations of STCDs, this review aims to support the development of more efficient traffic management strategies in Australian work zones.
STCDs are used widely in many countries, including the U.S.A., Europe, and even countries with limited resources. In North America, particularly the U.S.A. and Canada, STCDs such as portable signals, automated flagger assistance devices (AFADs), and temporary rumble strips are widely implemented in both urban and rural short-term work sites. Empirical studies from these regions have reported reductions in vehicle speeds by 10–20 km/h (15–17), highlighting the tangible safety benefits of such interventions. European countries, while still progressing toward broader deployment, have incorporated smart STCDs and queue warning systems (QWSs) ( 18 ).
The current literature on STCDs reveals a frequent focus on vehicle speeds as a primary indicator of work zone traffic control effectiveness (e.g., [13, 16]). This focus is understandable because of the contribution of speeding to work zone incident causation and severity. With much of the literature originating from the U.S.A., it is worth noting that in the locations represented, work zone speed limits and often pre-work speed limits tend to be higher than in Australia. As stated by Savolainen et al. ( 17 ), high-speed roads are typically subject to 16 km/h (10 mph) work zone reductions, with further reductions applied according to specific activities and conditions. In contrast, speeds on high-speed Australian roads are reduced for work zones by at least 20 km/h and usually more, with 40 km/h often imposed through work areas without positive protection, which is a substantially greater reduction than equivalent U.S. work zone sections.
STCDs are used for a variety of safety applications; by either influencing driver behavior, such as encouraging lower speeds and greater attentiveness, or by physically reducing the likelihood of human–vehicle interaction. STCDs, such as barriers, provide positive protection for workers by eliminating intrusion ( 19 ). Devices such as VMSs and speed feedback signs convey important messages to drivers to keep them informed ( 14 ). Devices such as portable rumble strips significantly help with speed reduction ( 18 ). The STCDs examined in this study are designed to enhance safety primarily by minimizing direct human exposure in work zones.
Stop/slow devices are of high importance and are widely used at work zones ( 20 ). The high risk to human flaggers in stop/slow operations has been recognized and documented over decades of work zone safety research (e.g., [21, 22]). Accordingly, the use of human flaggers is now clearly discouraged and avoided where possible on high-speed roads and elsewhere. As such, human flaggers as a stop/slow traffic control method are increasingly being replaced by PTLs or signals and AFADs (23, 24) across the world. Farid et al. ( 25 ) go on to identify two types of available AFAD, namely (i) the stop/slow AFAD (using interchangeable static signs) and (ii) red/yellow lens AFAD (using illuminated signals). These identifications do not include some additional components, functions, and variations on AFADs as evident in the literature, including devices with boom gate arms as trialed by Finley ( 5 ). While many alternatives are being used to replace human flaggers, Australia still relies heavily on human flaggers at work zones in some instances, including for short-term/mobile operations where space is limited.
To understand the Australian context, Debnath et al. ( 23 ) trialed remotely operated PTLs and mechanical stop/slow signs (AFAD) on a two-lane undivided rural Queensland highway. The study noted that the operation of these devices reduced worker exposure to traffic as intended, and drivers generally complied with the signs and signals. However, higher approach speeds and increased speed variance were observed compared with baseline conditions (human flagger), potentially increasing the risk of rear-end crashes. This latter finding tends to align with research indicating that drivers slow down more and are more compliant when they see workers on the road or road shoulder ( 26 , 27 ). Also relevant is the finding by Schrock et al. ( 28 ) that flagger presence was associated with higher compliance with respect to red light running.
Even though the AFAD is not widely used in Australia, remotely controlled PTLs are now a commonly preferred option to eliminate or reduce the exposure of human traffic controllers. While early PTL systems were powered by a combination of industrial batteries and diesel generators ( 29 , 30 ), advanced solar and battery-powered systems are now common, making the devices more efficient and practical in the field. Finley et al. ( 31 ) reported that some PTL devices are easier to use than others, a factor that is manufacturer dependent. This is something that should therefore be regulated and monitored.
In the U.S.A., commonly used STCDs are sometimes used as part of or in conjunction with QWSs ( 29 ), but may also supplement all forms of stop/slow controls, including PTLs and AFADs. Even though these devices can be used as STCDs, there are no clear guidelines on when and how to use these devices to improve the safety of work zones.
When considering the cost of STCDs, equipment costs for STCDs can be relatively high compared with human traffic controllers, particularly in the initial procurement phase. However, the use of STCDs can often reduce the number of traffic controllers required to implement and execute a traffic control plan, thereby reducing labor costs to provide a net benefit over time ( 21 , 28 , 30 , 31 ). While covered to some extent, studies noting potential or actual cost advantages (compared with alternatives) do not always adequately quantify cost–benefit ratios and related data for reliable conclusions.
The research by Finley et al. ( 32 ) evaluating innovative STCDs concluded that the prototype devices trialed would take from 1 to 4 years to become cost-effective (i.e., “pay for themselves”). Primarily examining driver understanding and comprehension of the devices, safety effects could not be quantified in the study, and similar statements have been made previously. Subsequently, while it is clear that STCDs are able to achieve the desired effect of reducing exposure to traffic, the actual reduction in incidents remains difficult to quantify. Additional potential benefits of STCDs, such as reduced exposure to adverse weather conditions or potential abuse from motorists, are also difficult to assess and not readily quantified. In addition to equipment and related transport costs, the installation and removal time of STCDs versus human traffic controllers alone is a factor that needs to be considered, particularly for works of very short duration. Finley et al. ( 32 ) reported that PTL and/or AFADs should not be considered for works of less than half a day duration.
While the cost of training traffic controllers to operate STCDs is not always reported or factored into STCD cost–benefit analyses, Patil ( 33 ) recognizes the potential costs of overlooking this important aspect and allowing untrained personnel to operate STCDs. Inadequate skills and competency can lead to poor device installation and setup, potentially increasing the risk of crashes, time and fuel costs, vehicle emissions, and driver frustration.
Several studies reviewed note the importance of training for STCD (e.g., [ 5 , 9 , 34 ]) use and for traffic control generally, also noting the additional cost of training for STCDs in some cases, but most do not go into detail on training requirements. Patil ( 33 ) reported that appropriate and adequate training is necessary to ensure that STCDs are correctly operated. Finley et al. ([ 32 ]) identify the need for training as one of the disadvantages of STCD use, specifically for PTLs and AFADs. Additional training is likely to be required for specific products and may or may not be available from suppliers and/or manufacturers.
There is strong evidence in the literature demonstrating that STCDs are generally effective for substantially reducing the exposure of traffic controllers to live traffic, although the overall safety benefits remain difficult to estimate. Cost–benefit analyses in the research suggest that even considering uncertain safety benefits and relatively high costs of initial acquisition/procurement, STCD use should at least be cost-effective over time and cheaper than traditional methods in many, if not most, cases. Therefore, it is important for Australian work zones to utilize the maximum advantages of STCDs. Research reviewed in this study provides useful guidance on what challenges are faced by Australian traffic controllers in using STCDs and traffic controllers' views on how to mitigate these challenges and improve the use of STCDs at work zones.
Methodology
Understanding the industry perception of STCDs and the associated challenges is important for identifying the barriers and facilitators to using STCDs. A series of industry consultations (n = 12) in a semi-structured focus group discussion (FGD) setup, followed by an online survey (n = 42), was undertaken with a total of 54 representatives from different traffic control companies and local/regional government agencies in New South Wales (NSW). This sample size of 54 companies approximately represents one quarter of all registered traffic control companies operating in NSW. The findings of the FGDs informed the design of the online survey.
To recruit participants for the FGD and online survey, a list of all registered traffic control companies operating in NSW was obtained from the state department of transportation (Transport for NSW). The list contained contact information of 247 traffic control companies, including the 128 local government agencies (known as councils) in NSW. It is noted that the councils typically use a combination of in-house and contracted TTM resources.
To recruit participants for the FGD sessions, email invitations were sent to all companies between June and July 2024, requesting engagement with a suitable representative who was directly involved in TTM design and/or delivery. A reminder email was sent to each company approximately 1–2 weeks after the initial email. A total of 12 companies were involved in 11 FGD sessions (all sessions had one participant each, except one that had two participants). The FGDs were held during July–October 2024.
The collected data from the FGDs were analyzed using a mixed analysis approach of thematic analysis and quantitative analysis. The findings were used to populate a list of themes/items for questions that were used in the second phase of consultations, which was administered as an online survey to reach a wider audience (i.e., to the broader traffic control industry). The survey included questions with pre-set answer options (as informed by the findings of the FGDs) and open-ended questions (to allow participants to provide information in addition to the pre-set answer options). The survey was designed and administered using an established research survey platform at Deakin University (Qualtrics).
Recruitment for the online survey followed a similar approach to that used for FGDs. All companies in the list, except those that participated in the FGDs, were invited by email to complete the online survey. The companies were requested to forward the invite to a representative who was directly involved in TTM design and/or delivery. Following the first email sent on 26 September 2024, a reminder email was sent about 3–4 weeks later, and the survey was closed at the end of October. A total of 42 responses were recorded, including 6 partial completions and 36 fully completed surveys. All responses were deemed suitable for analysis.
The survey responses were analyzed using a mixed thematic and quantitative analysis approach. Following descriptive analysis of the survey data, an ordered probit regression model was calibrated to further examine the reliability of PTLs and portable boom barriers as alternatives for human flaggers. Ordered probit models have been frequently used in the literature to analyze similar survey data (e.g., [( 35 , 36 )]). The model is formulated as shown in Equation 1:
where y is the latent variable presenting the ranking given for a strategy by the ith survey respondent with P being the number of survey respondents; X is a vector of observed independent variables with β being the coefficient of each independent variable. The observed level of reliability, Yi is determined from the model using two threshold values (μ1 and μ2) separating each rank in the preference scale, as in Equation 2:
Two separate models were calibrated for PTLs and portable boom barriers to identify how the employment characteristics of industry workers influence the perception of reliability of alternative STCDs for replacing human flaggers.
Data Description
The FGD participants (n = 12) were mostly male (85%) with an average of 9.2 years of experience in TTM. Most participants worked primarily in urban areas with companies based in the Greater Sydney area. The two council (regional/local government) representatives who participated were both at regional councils. Attempts were made to engage a larger number of government (council) representatives in FGD sessions but they were unsuccessful in the limited data collection timeframe.
The following online survey was open for responses for 2 months from October to the end of November 2024. The descriptive statistics of the online survey participants are shown in Table 1. Most participants identified as male (76%). About half of the participants had over 10 years’ experience in the TTM industry, about 67% were contractors or subcontractors, and 65% identified their primary work role as operations manager/coordinator. More than half of the participants reported working more than 30 h per week on average and another 31% reported less than 10 h per week.
Description of the Online Survey Participants
Note: TTM = temporary traffic management; TGS = Traffic Guidance Scheme.
Results
The results from the FGDs and online survey are presented in this section on the following themes: the commonly used STCDs, the perceived effectiveness and key benefits of using STCDs, the barriers and motivators for greater use of STCDs, and the reliability of STCDs as an alternative to human flaggers.
Commonly used STCDs
The FGD results showed that the STCDs mostly discussed by participants were PTLs and portable boom barriers. Other devices were identified by the FGD moderator as devices that can be used in work zones as STCDs. However, participants generally did not recognize those devices as necessarily being STCDs. Devices recognized by the FGD participants were only the ones that can be used for stop/slow operations.
Following the FGDs, a list of seven STCDs, namely human flagger, PTLs, portable boom barriers, a combination of PTLs and boom barriers, pilot cars, radar-activated speed feedback signs, and VMSs, was included in the online survey for the respondents to indicate the frequency of usage for each device. The frequency of usage was recorded based on the work zones where each device can be used. The survey results of the devices that can be used for stop/slow operations are shown in Figure 1.
Frequency of usage of supplemental traffic control devices (STCDs).
The most commonly used STCD was the human flagger. Around 92% of the respondents noted that the human flagger is being used at least “sometimes,” with 14% “always” using the human flagger. These results indicate that the TTM industry is using human flaggers more commonly than other STCDs that can reduce the exposure of human flaggers to live traffic at roadworks.
With PTLs and portable boom barriers being the two devices outlined as STCDs in Australian guidelines, the survey results indicate that while PTLs are used by more than 80% of traffic control companies, more than 50% of the respondents have never used the boom gate in their operations. More than 60% of the respondents did not use PTLs and boom barriers together.
Effectiveness and Key Benefits of STCDs
When the effectiveness of alternative STCDs to replace human flaggers was considered, more than 60% of the survey respondents perceived that PTLs are very effective devices that can be used as a replacement for human flaggers. The portable boom barrier was the second most noted STCD as “very effective.” The rate of responses is given in Table 2.
Effectiveness of Supplemental Traffic Control Devices in Replacing Human Flaggers
The online survey gathered respondents’ views on the level of difficulty in setting up STCDs (see Table 3). PTLs were rated as the easiest to set up among all STCDs considered. Because of the limited use of portable boom barriers, more than a third of the participants noted not having experience in setting up this device. However, about half of those who had experience of setting up such devices noted that they were “easy” to set up.
Difficulty Level in Setting up Supplemental Traffic Control Devices
The FGDs identified some key benefits and advantages of using STCDs to enhance safety at roadworks. Participants agreed that eliminating or reducing human flaggers’ exposure to traffic was the main benefit associated with using STCDs. One participant suggested that this was the only real advantage of STCD use. However, numerous additional benefits were identified by other participants, including providing a physical barrier, reducing traffic controller fatigue, reducing the risk of heat exhaustion, dehydration, and sunburns, stress reduction, allowing greater on-site mobility, and so forth.
Barriers and Motivators to Greater use of STCDs
Several barriers were identified that can discourage traffic controllers from using STCDs in work zones. These barriers include technical issues, logistical challenges, manual handling difficulties, cost–benefit perceptions, and resistance to change.
Barriers related to technical issues with respect to STCD operation were commonly cited by most FGD participants and more than half of the survey respondents. One FGD participant mentioned that technical problems occur on nearly every job. In addition, some PTLs and related devices require leveling to function properly. Tilt sensors, for example, can be triggered by heavy vehicles passing at moderate speeds, causing the PTL to enter "failure mode." Once this happens, the devices need to be reset. It was suggested that synchronization and pairing issues can be addressed through appropriate training and experience.
One participant explained, “Basically, if a truck (B-double) passes at 60 km/h (37 mph), which is the speed at most work sites, where the traffic controller is, and it’s 40 m behind, I guarantee you that the tilt sensor will go off unless you have at least 20 sandbags on that.”
Furthermore, questions were raised about the necessity of using tilt sensors in PTLs. Locking out the entire system can sometimes create more dangerous situations, such as long traffic queues. Furthermore, loss of synchronization can take up to 15 min to resolve, during which time additional traffic controllers are needed to manage traffic flow and fix the STCD issues.
Some operational barriers were noted by the study participants. It was noted that devices are often poorly maintained in the field, leading to more technical problems and increased off-site maintenance and repair needs. In addition, the device status may not always be recorded or reported when the equipment is returned to depots, which means that devices may be redeployed without undergoing necessary checks or repairs.
With respect to logistics and manual handling processes, some participants highlighted that tracking, auditing, and maintaining all devices can be a significant burden for businesses, especially when many individual devices are involved. The transportation and setup of specific devices may also pose challenges, as not all traffic control providers are adequately prepared. For example, one portable boom arm, weighing a claimed 90 kg, reportedly requires a crane for safe installation and removal. Other concerns related to manual handling processes included the time required to set up the devices and the physical labor involved, particularly for short-term or mobile work. Several participants raised this issue.
Given these challenges, the costs associated with using STCDs can be high, and these costs are ultimately passed on to clients. Multiple participants noted that some clients are hesitant to use STCDs, mainly because of concerns about costs outweighing perceived benefits. One participant mentioned, “Clients are often difficult to convince regarding the net benefit of STCD use.” It was suggested that educating clients on these issues, with a clearer demonstration of benefits relative to cost, could help address some of this resistance. However, it was also evident that traffic control providers are reluctant to invest in assets that are not used frequently. They need a return on investment and the ability to regularly invoice for the deployment of the devices. As a result, the cost can be an even bigger barrier for smaller traffic control companies, which may consider STCDs unnecessary.
As traffic control companies attempt to incorporate innovative STCDs into their operations, a lack of training and the rapidly evolving nature of STCD technology have emerged as major challenges. This has also led to some resistance from traffic controllers, especially in the early stages following the introduction of a new device.
While these barriers were identified primarily through the FGDs, the survey focused more on understanding what factors would motivate the traffic controllers to increase the use of STCDs at work zones (see results in Figure 2). Most survey respondents (around 62%) identified “lower product cost” as a key motivator for using STCDs on-site. Apart from cost, “product reliability’ and “greater clarity in guidelines” were selected as key motivators by more than 50% of the respondents. In addition, the respondents noted that increasing public awareness of STCDs can also act as a motivator to increase the use of STCDs on-site.
Motivating factors for using supplemental traffic control devices.
Reliability of STCDs
To assess industry perceptions on the reliability of alternative STCDs in reducing human flaggers’ exposure to traffic, survey respondents were asked to rate how reliable they believe the PTLs and portable boom barriers are as alternatives to human flaggers. These results were further analyzed using an ordered probit model. Only the PTL and the boom barrier were selected for this analysis as they are the two devices outlined as STCDs in most Australian guidelines (e.g., [ 10 – 12 ]). These two devices were also identified as most effective in replacing human flaggers by the respondents of this study, as noted earlier. From the survey responses received, 39 respondents completed the relevant questions and were included in the model. The coefficients of the regression models (i.e., beta values) and their statistical significance at a 90% confidence level are presented in Table 4. The negative coefficients show higher reliability when compared with the reference category, and positive coefficients represent lower reliability. The magnitude of the coefficients indicates the size of the change in the independent variable compared with the reference category.
Regression results for Portable Traffic Lights and Boom Barriers as an Alternative to Human Flaggers
Note: TTM = temporary traffic management; STCD = supplemental traffic control device; TGS = Traffic Guidance Scheme.
- Did not remain in the most parsimonious model.
Significant at a 90% confidence level.
The regression model results showed that experience in the TTM industry is a statistically significant factor when assessing worker perception of the reliability of STCDs. Compared with industry personnel with more than 10 years of experience, employees with less experience reported PTLs as less reliable and portable boom barriers as more reliable in replacing human flaggers. Compared with operations managers/site supervisors, survey respondents with other job roles (e.g., company owners, regional managers, and registered training course designers) believed that PTLs are less reliable as a replacement for human flaggers. The employees who use PTLs less frequently also believed that PTLs are less reliable in comparison with those who use PTLs frequently. Gender and working hours of employees were not significant at a 90% confidence interval in the PTL model.
With regards to the portable boom barriers, employees with less experience believed the boom gate is more reliable in replacing human flaggers when compared with employees with more than 10 years of experience. The portable boom barrier was believed to be more effective by employees working in regional/ rural areas when compared with employees who work in both areas. Survey respondents' gender, employment category, and work role were not statistically significant at a 90% confidence level, while working hours and the frequency of STCD usage were not retained in the most parsimonious model.
Discussion
STCDs are increasingly used in work zones worldwide to enhance driver and worker safety. While this study was conducted using Australian data, the insights gained have broader relevance and can inform practices in other countries facing similar challenges. In Australia, the adoption of STCDs in the construction industry has been primarily influenced by safety regulations and guidelines ( 7 ). One key guideline mandates the use of STCDs when work requires traffic to be stopped on roads with posted speed limits above 45 km/h, which has been a significant driver for their implementation. Even though these guidelines mandate the use of STCDs, Australia is not progressive in adapting to new STCD technology and is not up to date with the evolving STCD industry.
While STCDs are being developed and used globally to reduce human flaggers’ exposure to hazards on roads (e.g., [19, 37]), Australia still relies heavily on human flaggers for TTM at roadworks. Even though devices such as PTLs and VMSs are used in Australian work zones, traffic controllers often believe these devices are less reliable and less effective compared with human flaggers and therefore are reluctant to move away from traditional methods and devices. The regression model results in this study suggest that a traffic controller’s work experience in the TTM industry plays a significant role in their trust in STCDs. This suggests that less experienced traffic controllers should be educated on the potential benefits of using STCDs to strengthen their trust in these devices.
Traffic controller education and knowledge are often overlooked when assessing the effectiveness of a device. While it is important for devices to be effective, it is more important to be operated correctly. The traffic controller handbook outlines the importance of real-world application experience ( 38 ). The FGDs also highlighted the lack of proper training for new traffic controllers. Most Australian traffic control companies are not satisfied with the level of training and expertise brought in by the new staff. It is suggested that training should be provided on the use of innovative traffic control devices before an employee joins the workforce ( 37 ). The construction industry’s tendency to rely on established practices has made the introduction of new technologies, including STCDs, challenging. This lack of education and training has led to traffic controllers not being aware of the benefits of STCDs. Introducing structured training on innovative traffic control devices before new hires enter the workforce could therefore be a universally valuable strategy, especially in countries where the construction industry is similarly cautious about moving away from established methods.
The Australian guidelines related to STCDs can also be identified as a major factor for the inappropriate and limited use of STCDs in work zones. According to Austroads ( 7 ), STCDs will be used to provide warning or information, to slow down, stop, or redirect traffic, and also in emergency situations. While it is clear that STCDs can be used in any work zone that can create a hazard, it is yet unclear which STCDs to use when, and also what devices are classified as STCDs, especially when only PTLs and portable boom barriers are noted as STCDs in the guidelines. Therefore, it is recommended to add “example traffic control scenarios and preferred devices” to the guidelines. Tables with similar information are presented by Tapan et al. ( 39 ).
Given that the use of STCDs is a mandatory requirement in certain work zones, there are limitations on the range of initiatives that can be introduced, particularly when it comes to legal obligations. However, despite these constraints, there are several potential measures that could encourage more widespread and effective use of STCDs in Australia’s construction industry. One of the most impactful initiatives could be the introduction of tax incentives for companies ( 40 ) that adopt and implement STCDs, particularly for small and medium-sized enterprises that may find the upfront cost of these devices prohibitive. Offering financial incentives could help offset the cost burden and make STCDs more accessible to a broader range of companies.
In addition, mandatory training programs for traffic controllers and other personnel working in work zones could be implemented to ensure that they not only know how to use STCDs effectively but also understand their safety benefits. Proper training can improve confidence in using STCDs and help overcome skepticism around their reliability compared with human flaggers. Such programs could be structured into the licensing requirements for traffic controllers, ensuring that workers are adequately prepared for the evolving technology in their field.
Another crucial measure is the harmonization of standards across the industry. Currently, various jurisdictions in Australia have differing guidelines or regulations around the use of STCDs. Standardizing the technical specifications, performance expectations, and guidelines for STCDs across the country would ensure consistency, increase trust, and streamline their adoption. This could be achieved through collaboration between government bodies, industry associations, and manufacturers, creating a unified set of standards that support safety and innovation.
STCD manufacturers also have a significant role to play in encouraging greater use of these devices. By focusing on integration with intelligent transport systems ( 41 ), manufacturers can help make STCDs more effective in real-time traffic management. For example, STCDs could be designed to sync with other technologies, such as traffic lights or dynamic speed signs ( 42 ), to provide a more seamless flow of information and improve safety for both workers and drivers.
In addition, manufacturers can address one of the common concerns related to STCDs—power supply—by developing alternative, user-friendly power sources for the devices. Solar-powered batteries are a promising solution (e.g., [43, 44]), as they are cost-effective, environmentally friendly, and reduce reliance on traditional power sources. This would not only make STCDs more sustainable but also easier to deploy in remote or off-grid work zones, where access to electricity may be limited. Manufacturers could also explore battery life optimization and wireless communication options to reduce the need for frequent maintenance and improve the overall reliability of the devices.
These identified barriers, such as high initial costs, inconsistent guidelines, and limited training, are challenges also reported globally. For example, studies in the U.S.A. have highlighted cost as a primary deterrent to deploying AFADs and portable traffic signals (e.g., [27, 34]), alongside uncertainties about device reliability and the need for additional training ( 13 , 25 ). Similarly, European work zone studies ( 3 ) have identified concerns over operational complexity and driver comprehension of newer STCDs. These parallels indicate that the findings may support global efforts to increase the safe adoption of STCDs. Thus, this study contributes new empirical evidence on the organizational and perceptual factors that can inform international strategies to modernize temporary traffic control.
By combining these efforts, government support through tax incentives, standardized training in globally accepted STCDs, and industry-wide regulations, along with technological advancements and innovative power solutions from manufacturers, the adoption and effective use of STCDs can be significantly accelerated, ultimately enhancing safety in Australian work zones and beyond. Finally, industry awareness campaigns, along with case studies and live demonstrations, can further enhance the adoption and effective use of STCDs at future work sites.
Conclusions
Various STCDs are used in work zones around the world to enhance the safety of both workers and motorists, with their use often being mandated by regulations. However, in Australia, the adoption of STCDs remains limited compared with their usage in other countries, for example, the U.S.A. This study aimed to investigate the current use and adoption of STCDs in Australia and identify the barriers to their adoption as well as the motivators that could encourage their greater use not only in Australia but also globally. The research involved reviewing the literature and conducting significant industry consultations, including focus groups and an online survey among 51 temporary traffic control companies in NSW, Australia.
The results of these consultations revealed several key factors contributing to the limited use of STCDs. One major issue is the broad and sometimes vague nature of existing guidelines, which leave room for interpretation on which types of STCDs should be used in different work zone scenarios. In addition, concerns over the reliability, cost, and awareness of STCDs further discourage their adoption. Results indicated that greater clarity in the guidelines, specifically with respect to which STCDs are appropriate for various work zone conditions, would help streamline their use. Furthermore, improving public awareness about the benefits of STCDs and providing more comprehensive training for traffic controllers and financial incentives to traffic control companies could play a crucial role in overcoming existing barriers. The study findings provide new insights into the barriers and motivators of STCD use in work zones, which can help shape the future development of relevant guidelines and practices in encouraging the adoption of STCDs as an alternative to human flaggers. The study findings may be of particular interest in places where STCDs are currently underutilized and/or where use is inconsistent across jurisdictions and localities.
Footnotes
Acknowledgements
The authors gratefully acknowledge the input from participants of the FGDs and the online survey.
Author Contributions
The authors confirm contribution to the paper as follows: study conception and design: A. Debnath, R. Blackman; data collection: R. Blackman; analysis and interpretation of results: A. Debnath, R. Blackman, S. Siriwardene; draft manuscript preparation: A. Debnath, S. Siriwardene, R. Blackman. All authors reviewed the results and approved the final version of the manuscript.
Declaration of Conflicting Interests
The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Prof Debnath is an Associate Editor of the Transportation Research Record journal. All other authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was funded by The Civil Experts with support from Transport for New South Wales (TfNSW) and SafeWork NSW.
The views and opinions expressed in this paper are those of the authors and do not necessarily reflect the policies and practices of the funding organizations.