1. Introduction
The greatest hazard to public health in the twenty-first century is greenhouse gas emissions, which lead to global warming and climate change [
1]. California is the second-largest greenhouse gas emitting state, after Texas, in the US [
2], with its transportation sector accounting for the highest share of emissions. To comply with federal air quality regulations and climate change targets, the State of California has taken substantial steps, in the form of mandates, to convert medium-duty (MD) and heavy-duty (HD) trucks to low-carbon transportation alternatives [
3]. In California, a region characterized by a reliance on natural gas and solar energy, the average all-electric vehicle emits approximately 2261 pounds of emissions annually [
4]. As of 2023, the state has witnessed the registration of over 477,000 new electrified vehicles, constituting 35 percent of the total volume, with more than 336,000 being rechargeable, accounting for 25 percent of the total volume. Notably, all-electric vehicles contribute to less than half of the life cycle emissions, with approximately 35% of the total greenhouse gas emissions attributed to either the battery manufacturing process or the manufacturing of the cars [
5].
Low-carbon transportation prioritizes the reduction of carbon emissions to mitigate environmental impact. While energy efficiency is often a key component, it is important to recognize that low-carbon transportation encompasses a variety of strategies beyond simply minimizing energy consumption [
6]. The California Air Resources Board (CARB) developed several models to cut emissions by mandating low-carbon transportation (LCT) adoption in specific sectors. To facilitate compliance with such mandates in the on-road sector, the Hybrid and Zero-Emission Truck and Bus Voucher Incentive Project (HVIP) was established by CARB to provide vouchers that lower the upfront cost of clean trucks [
7]. Similarly, to encourage the off-road equipment (ORE) sector to adopt zero-emission vehicles, several incentive and regulatory programs were introduced, such as the Clean Off-Road Equipment (CORE) Voucher Incentive Project [
3], Agricultural Replacement Measures for Emission Reductions (FARMER) Program [
8], In-Use Off-Road Diesel-Fueled Fleets Regulation [
9], etc.
These incentive programs encourage the adoption of clean technology, leveling the playing field with conventional technology in terms of cost. However, due to a lack of infrastructural or financial backing, many fleet operators may be ignorant about the incentive programs or hesitant to implement new technologies. Furthermore, challenges exist in designing clean technology incentives for HDV and ORE organizations as they operate in a wide variety of applications, fleet sizes, engine configurations, and duty cycles. Therefore, there is a need to address the scarcity of research on LCT in the HDV and ORE sectors.
The major contribution of this study is twofold. The first contribution is contextual, as the study fills a key knowledge gap in the association between behavioral factors and LCT adoption in the HDV and ORE sectors. The research collects data from semi-structured interviews and analyzes the data using qualitative content analysis. The second contribution is methodological, as the study incorporates the assistance of generative artificial intelligence (AI) to refine the analysis and uncover potential contributions/shortcomings of generative AI technologies in qualitative research.
The study makes additional contributions to the literature by exploring the variation of factors influencing LCT adoption among organizations (with respect to their adoption behavior, vocation, and fleet size) and identifying possible discrepancies between available and expected government support for LCT adoption.
The rest of the article is organized as follows.
Section 2 reviews the literature exploring the current state of LCT adoption in the HDV and ORE sectors. The data collection steps are outlined in
Section 3.
Section 4 outlines the methods employed, and the results are discussed in
Section 5.
Section 6 presents a summary of the findings, recommendations, and future work.
5. Results and Discussion
The results from the content analysis were aggregated and compared based on LCT adoption behavior (three adopting organizations vs. nine non-adopting organizations), vocation (eight HDV organizations vs. four ORE organizations), fleet size (eight small-fleet organizations vs. four large-fleet organizations), and HDV hauling type (three long-haul organizations vs. three short-haul organizations vs. two mixed-haul organizations) (
Table 1 and
Table 2). The following sub-sections present the results of the content analysis and their implications.
5.1. Behavioral Factors of LCT Adoption
As previously discussed, behavioral factors (awareness and impression) may play an important role in the adoption of new technologies such as LCT. The following sub-sections discuss the association of these behavioral factors with LCT adoption and how the factors vary with respect to adoption behavior, vocation, and fleet size.
5.1.1. Awareness and Impression of LCT
On a scale of 0 to 3, the average awareness of LCT among the interviewed organizations was 2.5 (
Figure 3). However, subtle differences in awareness levels were observed among different groups of organizations with respect to adoption behavior, vocation, and fleet size (
Table 1). As expected, compared to large ORE companies and large mixed-haul HDV firms, smaller long-haul and short-haul trucking companies in the HDV sector showed a lower level of LCT awareness.
On average, adopters demonstrated a higher awareness of LCT compared to non-adopters, which is in line with our expectations. Non-adopters also included organizations having diesel fleets equipped with emission-reduction technologies. In the technology adoption process for organizations, awareness is recognized as the initial stage [
18]. Consequently, a higher level of awareness of LCT among current adopters is expected. Apart from assessing the role of awareness in current LCT adoption, its role in future LCT adoption was also assessed. It was found that interviewees who demonstrated a higher awareness of LCT were more likely to represent organizations planning to adopt LCT or expand their LCT fleet (
Figure 4). These findings highlight a positive association between awareness of LCT and LCT adoption.
When the behavioral factors were compared among different vocations and fleet sizes of organizations, the positive association between awareness of LCT and its adoption held true; subgroups of organizations with higher awareness had a larger share of adopters. The ORE organizations had a higher awareness of LCT compared to the HDV organizations. At the same time, three out of four ORE organizations were adopters (compared to zero adopters among the HDV organizations) (
Figure 1). Similarly, small-fleet organizations, which had a lower proportion of adopters (one adopter out of eight small-fleet organizations compared to two adopters out of four among large-fleet organizations), were found to exhibit a lower level of awareness compared to large-fleet organizations. These smaller organizations are usually aware of LCTs but lack comprehensive knowledge on factors like financing and technology [
38].
Although none of the HDV organizations adopted LCT, the mixed-haul organizations had a higher awareness of LCT compared to the other HDV organizations (short-haul and long-haul).
Although a positive association between awareness of LCT and its adoption was noticed, the same cannot be said about the impression of LCT. Adopters and non-adopters alike had negative impressions of LCT. The dissatisfaction with LCT among adopters might be explained by the technical limitations of LCT (discussed in the next sub-section). The negative impression may also be attributed to the intrinsic beliefs, business values, and strategic motives of the organizations [
15]. The overall impression of LCT among the organizations was somewhat negative to highly negative, with a rating of −1.17 (
Figure 3). Among all the groups of organizations, the mixed-haul HDV organizations had the most unfavorable impression of LCT (
Table 1).
5.1.2. Awareness and Impression of Incentives
On a scale of 0 to 3, the overall awareness of incentives among the organizations was 2.17 (
Figure 3). This was lower than the awareness of LCT. On a scale of −2 (highly negative) to +2 (highly positive), the overall impression of incentives that they had on incentives was 0.08, in contrast to their somewhat negative (−1.17) impression of LCT (
Figure 3).
Similarly to the findings on awareness and impression of LCT, the awareness of incentives was higher among adopters compared to non-adopters (
Table 2). The adopters also had a positive impression of incentives. In addition,
Figure 5 shows that interviewees who demonstrated a higher awareness of incentive programs were more likely to represent organizations planning to adopt LCT or expand their LCT fleet. These findings underscore the importance of awareness regarding incentives in the adoption of LCT. This necessitates information dissemination of available incentive programs [
38] to foster LCT adoption.
The assessment of awareness of incentives for different adoption behaviors, vocations, and fleet sizes (
Table 2) further underscores the positive association between awareness of incentives and LCT adoption. The overall awareness of incentives among ORE organizations, who were mostly adopters (three out of four), was higher than that of the HDV organizations, who were all non-adopters. Similarly, the large-fleet organizations, who had a higher share of adopters, were more aware of incentives than the small-fleet organizations. While it is important to raise awareness levels among these small-fleet organizations, it is also important to acknowledge that government agencies find it more difficult to reach out to them [
39]. Although none of the HDV organizations adopted LCT, the mixed-haul HDV organizations demonstrated the highest awareness of LCT incentives (similar to awareness of LCT) compared to the other HDV organizations (short-haul and long-haul). The diverse vocations and vehicle range [
40] prevalent within mixed-haul organizations might make them more aware of LCT and factors (e.g., government incentives) associated with LCT.
Although seven out of nine potential adopters of LCT had a high or moderate awareness of incentives, two interviewees with low awareness of incentives also stated their intention to adopt LCT (
Figure 5). One of these organizations stated that they intend to adopt LCT only because they are mandated (by environmental regulations) to do so. The other organization mentioned fuel efficiency and environmental friendliness of LCT as contributing factors to their intention to adopt. It is important to further explore why organizations intend to adopt LCT despite their lack of awareness about LCT incentives. Such explorations can achieve information saturation by including a larger sample of interviewees from this subgroup.
The analysis of impression revealed subtle differences with respect to adoption behavior, vocation, and fleet size of organizations (
Table 2). More importantly, it was found that lower awareness of incentives does not necessarily lead to a more negative impression. For instance, the small-fleet organizations had a lower level of awareness of incentives (compared to the large-fleet organizations), but their impression was better, suggesting that they perceived incentives as more valuable.
5.1.3. Environmental Awareness
A positive association between environmental awareness and potential to adopt LCT was also observed from the analysis. The five interviewees who demonstrated some level of environmental concern/awareness during the interviews represented organizations that are planning to adopt LCT (
Figure 6). This suggests that there exists a positive association between general environmental awareness and the intention to adopt LCT in the HDV and ORE sectors. Similar associations have been confirmed in the light-duty sector by several studies [
41].
Four organizations did not demonstrate general environmental awareness but intended to adopt LCT (
Figure 6). Three out of these four organizations mentioned that they intended to adopt LCT because of environmental regulations. One of these four organizations mentioned the low cost and frequency of maintenance as factors motivating them to adopt LCT. Future studies can narrow down their focus on this sub-group of organizations and explore them further.
5.2. Other Factors Influencing LCT Adoption
Although behavioral factors are important determinants of LCT adoption, they are not the sole determinants. This section discusses the other factors influencing LCT adoption (facilitators, barriers, general consideration), and their varying importance for different adoption behaviors, vocations, and fleet sizes.
5.2.1. Facilitators
The three most important facilitators of LCT adoption were environmental regulations (1.67 on a scale of 0 to 3), environmental friendliness of the vehicles (1.17 on a scale of 0 to 3), and green public relations (0.5 on a scale of 0 to 3). Although environmental regulations were the most important facilitator, they did not always lead to AFV adoption. Instead of adopting AFVs, many interviewed organizations complied with environmental regulations by adding DEF filters to diesel vehicles.
Table 1 presents the most important facilitators for different groups of organizations. The contrast between the facilitators for HDV and ORE organizations offers valuable insight into the diverse drivers behind Low-Carbon Transportation (LCT) adoption within different sectors. Environmental regulations stood out as the pivotal facilitator for LCT adoption among HDV organizations, while ORE organizations emphasized environmental friendliness and green public relations as their top facilitators. Past research has verified the tendency of organizations to expand their low-carbon fleet as a strategic move to enhance public image [
14]. In this regard, one of the ORE interviewees mentioned,
“Well, we’re located right near Silicon Valley in California. So, a lot of high-tech companies use biodiesel or low-CARB emission-type equipment. We try to cater to them a little bit”.
Interestingly, infrequent maintenance, a facilitator acknowledged in prior research [
15], was among the most important ones for small organizations and adopting organizations. An interviewee from a small-fleet organization stated,
“They’re relatively maintenance-free, so I don’t have to worry about checking the oil on them every time I start it up, I don’t have to worry about air filters clogging up”. Since smaller fleet organizations are expected to have limited resources, the infrequent maintenance of LCT might facilitate their adoption in these organizations.
5.2.2. Barriers
In the context of our study, “barriers” refer to the challenges or obstacles that hinder the adoption of LCT technologies within HDV and ORE fleet sectors. These barriers encompass a range of factors such as lack of refueling/recharging facilities, high purchase costs, low vehicle range, resistance to change, and technical limitations, among others.
When the barriers were individually ranked, lack of refueling/recharging facilities (1.92 on a scale of 0 to 3), high purchase cost (1.5 on a scale of 0 to 3) and low range (1.42 on a scale of 0 to 3) were found to be the three most important ones.
Table 1 presents the biggest barriers for different groups of organizations.
Significant insights can be drawn from the biggest barriers faced by adopters and non-adopters as well as those faced by small-fleet and large-fleet organizations. The most important barriers for adopting organizations and large-fleet organizations were from the technical category, suggesting that technical barriers may hinder their LCT fleet expansion, even after they have overcome the financial barriers to adopting them. However, these financial barriers were among the biggest barriers for small-fleet organizations and non-adopters. Hence, incentives aimed at mitigating financial barriers are particularly vital for smaller non-adopting organizations. These incentives may foster adoption among small-fleet organizations, as these organizations are argued to be innovative, flexible, and more receptive toward new technologies [
18].
One of the less common but important barriers that came up during the interviews was resistance to change. As one of the interviewees mentioned, “
The reason we wouldn’t change is because it’s a total change in our operation and that would be expensive”. The theory of psychological inertia (a tendency to repeat specific behaviors) [
42] may explain this resistance to change. The government could consider introducing accessible vehicle leasing schemes for non-adopters to experiment with new LCT models and possibly reduce their psychological inertia. Additionally, to make the change in operations smoother for these organizations, the regulators might want to consider a phased transition towards LCT rather than implementing an “all-at-once” policy [
43]. Another less common but significant barrier was the inability of LCT to meet demanding requirements (e.g., operating at 125 degrees Fahrenheit, carrying heavier loads). This could pose a legitimate obstacle because the already limited range of LCT (especially electric vehicles) is further diminished by challenging conditions such as heavy loads and high temperatures [
44].
5.2.3. General Considerations
Apart from facilitators and barriers to LCT adoption, the interviews featured some general considerations that organizations make when purchasing any vehicle (
Table 1). Among the different considerations, operating cost (1.92 on a scale of 0 to 3), purchase cost (1.58 on a scale of 0 to 3), and presence of incentives (1.33 on a scale of 0 to 3) were among the most important considerations.
The general considerations for adopters and non-adopters align with the findings from the barriers section; LCT-adopting organizations were more concerned about technical considerations while the non-adopting organizations were more concerned about the financial considerations. Operating cost was the most important consideration for long-haul and mixed-haul organizations, attributable to their heavier load and higher energy requirements [
45]. For short-haul organizations, the most important consideration was the purchase cost. For small organizations, incentives were among the top three considerations for vehicle purchase, unlike the large organizations.
5.3. Existing Incentives and Expected Government Support
Although monetary incentives were stated as important considerations for vehicle purchase, the interviewees mentioned six different factors that negatively influence the impression of incentives. These factors unveil discrepancies between the expectations of the organizations and the current state of government support for LCT adoption. Hence, these factors need to be addressed to realize the potential of incentives as facilitators of LCT adoption. The factors can be ranked in the following order: conditions/restrictions (0.67 on a scale of 0 to 3), difficulty to acquire (0.58), cost ineffectiveness (0.50), distrust of government (0.50), bureaucracy (0.25), and waiting period (0.25).
Conditions/restrictions frequently came up as an important factor (especially among small and long-haul organizations), determining the impression of incentives. One interviewee stated that applying for incentives would mean that a huge chunk of his operations would be restricted within California only and it would be detrimental to his/her business. To make incentives more lucrative for organizations, it is imperative to remove burdensome restrictions and streamline the application process to the extent possible [
38]. Another important factor that came up during the interviews was distrust of the government. When talking about the lack of trust the industry has in the government, one of the interviewees stated,
“Any government involvement, the more it’s under the radar, I think the more effective it’s going to be, knowing the industry like I do”. Hence, even though regulatory/punitive environmental mandates cause diffusion of LCTs, they may make organizations less receptive to rewarding interventions (e.g., incentives) coming from the government. Therefore, it is recommended that policymakers recognize this tradeoff and use punitive interventions sparingly [
46].
When asked about expected forms of government support, the organizations mentioned charging infrastructure support (1.75 on a scale of 0 to 3), monetary incentives (0.92 on a scale of 0 to 3), and collaboration with manufacturers (0.5 on a scale of 0 to 3) as the three most important ones. Since the lack of charging/refueling infrastructure came up as the most important barrier, it is expected that the organizations would be seeking charging infrastructure support. However, some interviewees also suggested potential technological improvements such as swappable batteries [
44] and solar chargers, where the government can allocate resources. The government may also consider supporting manufacturers to come up with range extender technologies [
47] to mitigate the challenges of limited range. A statement from one of the interviewees emphasizes the need for technological improvements [
15] and suggests that financial incentives are not enough to ensure long-term diffusion of LCT. He/she mentioned, “
The incentives don’t make up for the short-range on the electric vehicles. You know the incentives don’t overcome the problems they just offer you a little cash to deal with the problems indefinitely”.
Given the heterogeneous landscape of the HDV and ORE sectors, the factors influencing the impression of incentives and expected government support differed for different groups of organizations (
Table 2). Hence, targeted incentive programs tailored to the varying expectations of organizations may prove to be an effective approach [
38].
5.4. Generative AI in Content Analysis
Although the AI coding tool on ATLAS.ti is still at its preliminary stage of development, using it as an assistive tool revealed ways in which generative AI can positively contribute to qualitative research.
Firstly, the codes produced by a generative AI tool can provide a summary of the studied material, and the human coders can use the codes to validate the original framework or identify new concepts overlooked by the framework. In this study, only 18 (4.5%) out of the 399 AI codes were found to capture new concepts which were not already identified by the original coding framework. Hence, it was an indication that the original framework captured most of the concepts relevant to the research questions. However, the AI tool offered a new perspective, and the original framework was refined using the 18 codes that captured new concepts. For instance, the subcategories “resistance to change” and “inability to fulfill extreme requirements” produced by the AI tool were newly added under the pre-existing main category “barriers to LCT adoption”. The AI tool also produced a main category named “environmental awareness” which was found to have a positive association with the potential to adopt LCT.
Secondly, a generative AI tool can identify new statements that belong to existing categories of the original coding framework. For instance, the sentence “Well, we would like to see some history of fleets that have changed over and what they ran into, to decide on how soon we’d want to change” was assigned the code “unproven technology” by the AI tool. Although “unproven technology” was a pre-existing subcategory (under “barriers to LCT adoption”), the human coders did not assign a category to the aforementioned statement during the manual coding phase. However, upon reevaluation of the statement, the code “unproven technology” was found to be a suitable subcategory for the statement.
Thirdly, generative AI can be used as a suggestive tool to find more suitable names for categories in the original coding framework. For instance, the subcategory “paperwork” (under the main category “reasons behind negative impression of incentives”) was more aptly changed to “bureaucracy” as it provided a more general description of the content being analyzed [
48].
Apart from the positive contributions of generative AI in this study, some potential areas of improvement were also discovered. Firstly, a generative AI tool needs to be fine-tuned to gather numerous statements sharing the same meaning under one code. Unless the tool can accomplish this task, the purpose (saving time) of using AI in a qualitative study would be defeated. This was especially prevalent in this study as 296 (74.2%) out of 399 codes generated had only one statement associated with them. This is an issue because coding is meant to reduce the data instead of proliferating it [
49]. Hence, even though the generation and assignment of codes using an AI tool takes very little time, aggregating codes to summarize the data may consume a considerable amount of time depending on the number of codes generated. Secondly, a generative AI tool needs to detect the nuances in natural language almost in the same way a human being can. Unless the AI tool can detect such nuances, it may assign wrong codes to statements. For instance, the AI tool inappropriately assigned the code “environmental concern” to the statement “
We were motivated to acquire low-carbon vehicles because California was imposing some restrictions”. Although the organization did purchase low-carbon vehicles, they did so because of legal restrictions, not because of environmental concern.
6. Conclusions
This study employed generative AI-assisted content analysis to understand the association of behavioral factors with LCT adoption and explore the variation in factors influencing LCT adoption among different groups of organizations (with respect to adoption behaviors, vocations, and fleet sizes). Moreover, the study also identified some discrepancies between expected and available government support for LCT adoption.
With regard to the behavioral factors, a positive association was found between potential to adopt LCT and awareness of LCT. A positive association was also noticed between the potential to adopt LCT and awareness of different aspects (incentives and the environment) linked to LCT. This underscores the importance of raising awareness levels within organizations regarding factors linked to LCT. To this end, the government could consider introducing accessible vehicle leasing schemes for non-adopters to experiment with new low-carbon technologies. Moreover, they should invest more in educational/outreach programs to increase the awareness of available incentive programs. The smaller long-haul and short-haul trucking companies operating in the HDV sector were found to have a lower level of awareness of LCT (compared to the ORE companies and larger mixed-haul HDV companies). Therefore, these organizations may be prioritized when planning initiatives designed to increase organizational awareness of LCT. However, further research is needed to confirm this.
The factors (including behavioral factors) influencing LCT adoption varied with respect to different adoption behaviors and vocations, suggesting a need for tailored incentives to facilitate LCT adoption among different groups of organizations. Environmental mandates were the most important reason behind LCT adoption in the HDV organizations, while the ORE organizations were mostly driven by environmental concern and opportunities to form green public relations. The financial barriers received greater importance among the non-adopters and smaller organizations compared to the larger organizations. On the other hand, for adopters and larger organizations, technical barriers received paramount importance.
The analysis of statements on available incentives identified a range of issues (e.g., conditions/restrictions, difficulty to acquire) with existing incentive programs that may limit their effectiveness as facilitators of LCT adoption. Hence, in order to ensure that government support initiatives actually result in LCT adoption, these issues should be addressed. Moreover, the analysis results suggest that the government should extend further support to charging infrastructure and technological improvements.
By using generative AI as an assistive tool, some additional insights were uncovered from the data which the human coders overlooked in their analysis. This suggests the potential of this emerging technology to validate and refine the coding framework used in content analysis. However, to achieve better results, the ability of generative AI tools to produce aggregate-level codes and identify the nuances of natural language needs to be ensured. A limitation of our study is that the AI coding tool used in ATLAS.ti 23 relies on pre-trained transformer (GPT) language models [
37]. It is essential to note that our study does not involve the training of this model, potentially affecting the customization and specificity of code generation for our unique research context. For future studies, exploring the implications of fine-tuning or custom training the AI coding tool within ATLAS.ti 23 is crucial. This exploration could offer insights into optimizing the tool’s performance for specific research contexts, thereby enhancing its adaptability and precision. Additionally, delving into the impact of different pre-trained language models on code generation within the tool would provide a nuanced understanding of its capabilities and limitations. Addressing these aspects would significantly contribute to refining the application of AI coding tools in qualitative research methodologies.
The organizations which were interviewed for this study exhibited as much variability as possible in terms of adoption behavior, vocation, and fleet size. However, there are other organizational differences that were not captured in the sample. Hence, future research can explore heterogeneity in LCT adoption behavior based on other such differences (e.g., operations, energy demands, duty cycles) among HDV and ORE organizations. These future studies can leverage the power of generative AI, finding more creative ideas for its application as technology evolves.