Accessibility is seen as a helpful notion that may be utilised to create insights into difficulties connected to social exclusion caused by a lack of transportation alternatives. Affordability should be a part of sustainable mobility ^[1][2][92,93]. Several studies have emphasised the importance of transportation equity: An equal distribution of transportation services (infrastructures and transit systems) aids in attaining social justice, with significant implications for health and quality of life ^[3][94]. Martens ^[4][95] suggested a thorough investigation of equity in transportation development. Beyazit ^[5][96] suggested a study of the literature on social impartiality in transportation. Delbosc and Currie ^[6][97] suggested using Lorenz curves and the Gini coefficient to measure public transportation equity, which has since been used in many other studies ^{[7][8][9][10][11][12]}[98,99,100,101,102,103]. Camporeale et al. ^[13][104] considered the importance of fairness and proposed a solution for achieving an equal allocation of transportation impacts (benefits and costs) among consumers. Camporeale et al. ^[14][15][16][105,106,107] proposed a methodology for planning and designing public transportation routes that address the demands of cities while promoting equitable access. Gallo ^[17][108] suggested a method for improving the price equity of transportation systems. Caggiani et al. ^[18][109] concentrated on implementing a cordon-based congestion pricing system on a multimodal network where private vehicles and public transit coexist and included a sensitivity study for a monocentric metropolitan reality by adjusting the scale of the charging area and the volume of the toll.

Attaining equity goals should be one of the transportation policy’s guiding standards. Any deal in this field that uses public funds and equity must be included in transportation planning. Sustainable mobility is inherently rational, provided that the poorer social classes often writhe the most from pollution and climate change.

Pricing may normally be applied to the use of road facilities or car parking. A toll is levied on car drivers for the use of a single piece of arrangement or for accessing a certain part of a city, and the driver is responsible for paying for parking. In terms of sustainable mobility, the policies seek to raise the relative costs of private vehicle usage in order to encourage a modal break in favour of other means of transportation, such as mass transportation, cycling, and walking. Often, road pricing has a straight environmental implication, discriminating prices based on the vehicle’s environmental compatibility ^[19][20][21][110,111,112]. In order to achieve competitive mobility, road pricing should be closely related to the principle of external costs ^[22][113]; in fact, the best road pricing should be that which is capable of charging the car user with all of the external costs it generates ^[23][24][114,115]. Indeed, optimal pricing is not feasible from this perspective, and parking pricing and road pricing strategies are still regarded as second-best approaches ^[25][116].

Taxation policies on fuels or car ownership are commonly used in Western countries, distinguished from environmental effects and greenhouse gas emissions. Santos ^[26][117] calculated and compared petrol and diesel taxes for 22 European countries, taking into account the impact of fuel taxation on fuel efficiency. Steinsland et al. ^[27][118] investigated the climate, financial, and equity implications of a fuel tax, a road toll, and a commuter tax credit. According to the research by Montag ^[28][119], fuel taxes are the primary tool for reducing automotive emissions. Using data from the US airline industry, Fukui & Miyoshi ^[29][120] investigated the impact of an increase in aviation fuel tax on cuts in fuel usage and carbon emissions.

The use of various sorts of incentives in transportation systems to develop sophisticated transportation congestion management solutions has recently received a lot of attention. Rather than employing assumed or fixed-amount rewards, Xiong et al. ^[30][121] examined integrated and individualised passenger information and suggested an incentive strategy to encourage more energy-efficient travel and mobility decisions. Herradoe et al. ^[31][122] proposed the idea of “incentivized sustainable mobility” that encompasses four stakeholders: residents, municipalities, commerce, and mobility services. According to the investigations of Ricci et al. ^[32][123], incentive-based strategies might promote the adoption of sustainable transport. Their research lays the groundwork for creating sophisticated algorithms capable of tracking mobility and incentivizing people’s habits concerning sustainable mobility. Some literature on the incentive approaches in transportation systems is tabulated in Table 14.

Government subsidies play a vital role in the adoption of sustainable transportation ^{[42][43][44][45]}[133,134,135,136]. Zhang and Huang investigated the vehicle product-line strategy in the context of government subsidy schemes for electric/hybrid automobiles ^[42][133]. Ouyang et al. ^[43][134] examined the entire cost of owning an electric car in China in the post-subsidy period. They discovered that the elimination of the buying subsidies, as well as the proliferation of COVID-19, had a substantial impact on Chinese customers’ purchasing intentions for EVs. Their findings indicate that tiny BEVs will attain parity before 2025, but medium and large BEVs will do so by 2030. They discovered that incentive programmes have a large influence and that oil prices are expected to considerably influence the time it takes for EVs to achieve parity. As a result, policymakers should implement incentive programmes to ensure a seamless transition to China’s vehicle fleet electrification. Li et al. ^[44][135] investigated the influence of the Chinese government’s subsidy plan for hydrogen filling stations on the market dissemination of hydrogen fuel cell cars (HFCVs). Their model suggests that the dynamic subsidy mode, which is based on an experience weighted attraction method, outperforms the static subsidy mode. They discovered that selecting an effective first subsidy scheme can improve HFCV sales by about 40%. Their findings reveal that early government intervention in establishing first HRSs can boost market diffusion efficiency by more than 76.7%.