1. Introduction
The World Health Organization (WHO) statistics suggest that approximately one billion individuals worldwide experience some form of disability, accounting for almost 15% of the global population [
1]. This number is expected to increase drastically in the coming years due to factors such as aging populations, an increase in road traffic accidents, and the spread of chronic diseases. Individuals with mobility aids (IMAs) have the intrinsic right of equity to public facilities and services; therefore, ensuring a user-friendly urban and social environment is essential. A significant proportion of the disabled population in the country (over 1.3 million) faces physical disability-associated challenges, as reported by the General Authority for Statistics (GAS). Among these, mobility impairments account for over 50% of the disabled population [
2]. These numbers are expected to increase soon, especially with the prevalence of chronic health conditions, inactivity, and rising traffic accidents. Hence, assessing the specific needs associated with IMAs is crucial for securing accessible pathways for daily activities and public amenities.
Disability remains a significant socioeconomic concern, particularly in developing countries, including the Kingdom of Saudi Arabia [
3]. As per recent statistics, over half a million individuals, accounting for 3.3% of the country’s population, are faced with some disability-related issues [
4]. The government fully appreciates the situation and established the King Salman Center for Disability Research (KSCDR) in 1991 to facilitate people with disabilities in all aspects and support research on the topic [
5]. In 2016, the Rights of Persons with Disabilities Act replaced the previous act of 1995 to ensure the self-respect of this special group of people and equal opportunities with dignity [
6]. Vision 2023 of Saudi Arabia also protects the rights of disabled persons by improving the country’s services, care, rehabilitation, and prevention mechanisms. Nevertheless, urban road infrastructure is yet to be evaluated for uninterrupted and convenient mobility.
While commuting for routine journeys, individuals with mobility impairments face numerous obstacles, such as a lack of sidewalks, steep slopes, absence of ramps, and refuge areas at public spaces and pedestrian crossings. Even though IMAs are entitled to free movement and equal access to services, smooth accessibility remains a persistent concern. This situation requires policymakers and urban planners to prioritize accessing essential services/amenities for IMAs. Mobility aid devices such as electric or manual wheelchairs are not designed to cater to uneven surfaces or steep slopes, unlike vehicular navigation. Pathway planning is another critical issue with IMAs’ journeys, which can become quite complex due to constrained urban environments and pathway alternatives [
7]. Although some prior research has been undertaken for pedestrian pathway planning, only a few studies have addressed the need for accessibility for IMAs in urban areas.
Traditional methods for pedestrian commuting are often based on consideration of travel time and distance, ignoring the unique challenges associated with wheelchair users. For instance, from the perspective of wheelchair users, longer pathways without barriers may be preferred over shorter pathways with steep slopes and obstacles [
8]. Studies have reported that wheelchairs travel longer than regular pedestrians to reach identical destinations. A recent study found that compared with powered wheelchair users or scooter users, manual wheelchair users, on average, travel 35% farther than their counterparts to reach the same destinations [
9]. These findings highlight the importance of identifying the specific accessibility barriers for IMAs in urban environments [
10]. Improving the accessibility of IMAs could benefit them by providing access to healthcare, social interaction, and employment opportunities [
11]. Historically, the transportation planning framework is based on maximizing performance and efficiency [
12]; however, contemporary planning involves prioritizing accessibility as a core component of sustainable urban development [
13]. Countries worldwide have legislated accessibility laws for IMAs, which mandate public infrastructure accessibility for all. For instance, the 1990 Americans with Disabilities Act (ADA) was proposed to enhance accessibility to public spaces in urban areas [
14]. Despite this legislation, municipalities and local governments worldwide struggle to meet the required accessibility standards, leaving IMAs at a potential disadvantage [
15]. In this regard, communities frequently face limited data on specific barrier removal, lack of infrastructure [
16], and inadequate information about the sidewalks’ accessibility [
13].
Travel is essential to daily life, facilitating independence and routine social interactions [
17]. The concept of “accessibility” refers to the ease of reaching a destination based on multi-criteria metrics and has been the subject of widespread discussion among urban planners, geographers, and economists [
18,
19]. Various statistical methods are proposed for evaluating the accessibility within pedestrian networks in urban regions. Accessibility analysis involves identifying and calculating accessibility indicators tailored to the target population, travel modes, and destination types, which may be quantified in terms of cost, distance, or time to form an accessibility index [
20,
21]. Multi-criteria Decision Analysis (MCDA) has been widely employed for accessibility assessment [
22,
23], which involves assigning weights to criteria based on relative significance and handling the fuzziness of individual judgments.
A critical review of the extensive literature on urban pathway optimization for disabled users reveals several gaps. First, existing studies have predominantly focused on accessibility optimization for regular pedestrians, ignoring the specific needs and dynamics of disabled users [
24,
25]. Understanding the travel satisfaction and preferences of IMAs is vital for the planning and designing of disability-inclusive urban infrastructure [
26]. Second, traditional pathway optimization methods are aimed at improving performance [
27] and reducing travel [
28] and often overlook critical indicators such as surface continuity, pathway gradients/slopes, pathway lengths, unction frequency, sidewalks, and crossing characteristics, which can significantly affect the commute, accessibility, and safety of disabled users [
12]. Third, the existing model primarily relies on pathway accessibility estimated based on established guidelines and standards [
29] and rarely incorporates user perceptions and perceived accessibility. Evidence from the literature suggests that user perception and satisfaction could provide valuable insights and recommendations for disability-inclusive urban infrastructure [
30,
31]. Lastly, while few studies have used MCDA, including AHP or TOPSIS, for pathway optimization for PWD [
12,
32,
33], limited work has considered Fuzzy Synthetic Evaluation (FSE) coupled with Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE), specifically to accommodate the subjectivity and imprecise judgments in users’ perceptions under complex built environment factors in urban centers [
34]. FSE is robust in capturing the inherent subjectivity in user preferences by accommodating the ambiguity in human judgments by transforming qualitative preferences into quantitative sets [
35]. The perception of IMAs is critical when using subjective or Likert-scale ratings to prioritize built environment factors like slope, pathway length and surrounding sidewalks’ characteristics. Once these critical factors’ importance weights and performance scores are established, PROMETHEE II (i.e., a more recent version of PROMETHEE) can develop outranking relationships between different pathways, allowing for easy and useful comparisons among the alternative pathways. Integrating FSE and PROMETHEE II provides a reliable and robust MCDM framework, accounting for users’ perception of subjectivity and the physical accessibility features of the urban network.
The current research study contributes to the literature by integrating FSE and PROMETHEE II to model user perception-based optimal pathway selection for disabled individuals in urban areas. The proposed modeling framework considered the objective pathway selection criteria (e.g., pathway length, pathway slopes, number of junctions, and sidewalks characteristics) and subjective user evaluations for optimizing the pathway selection. This hybrid scheme allows for a more accurate reflection of disabled users’ preferences, minimizing the ambiguity in human judgments. By ranking and prioritizing pathways based on user perception and pathway data, this research provides meaningful insight and a decision-support model for urban and transportation planners to enhance the accessibility of this road user group. The results are expected to guide the local authorities by identifying the pathways that balance physical accessibility features and user perceptions.
The present study has developed a framework to facilitate the pathway selection process for IMAs in different regions of Saudi Arabia, which may be adopted in urban areas in other jurisdictions. The study aims to (i) define the criteria (factors of built urban infrastructure along the pathways) that capture IMAs preferences, (ii) establish the relative significance of each criterion using FSE, (iii) determine criteria scores using Geographic Information Systems (GIS) and expert insights, and (iv) apply PROMETHEE II to establish outranking relationships among different pathways in a given region of Saudi Arabia.
2. Related Works
Urban centers are hubs of social, cultural, and economic activities. While efforts have been made to improve the sustainability and inclusivity of urban design and instruction, several mobility-related challenges are persistent for PWD [
36]. These individuals face significant challenges navigating urban road infrastructure, restraining participation, and social engagement [
37,
38]. A recent study highlighted several critical environmental, system-social, and barriers to daily commutes among disabled people and found that these individuals make 10–30% fewer trips compared to those without disabilities [
39]. Prior studies have proposed applying the shortest path algorithm to improve pedestrian social integration [
40]; however, this approach may not be optimal for those with mobility impairment [
41]. Instead, the best pathway is often coined, considering the necessary accommodations (such as ramps or drop curbs), allowing easy and safe navigation for IMAs [
42,
43]. Studies in this regard are often small-scale and have limited applicability in broader contexts. For instance, Karimi et al. [
44] proposed a novel personalized accessibility map (PAM) tool that can inform PWD users about potential accessible pathways and pathway selection based on their specific needs. The developed PAM-Pitt prototype can guide wheelchair users in identifying and locating suited campus entrances and efficient internal building pathways. The proposed system was based on ADA standards, considering various indicators such as surface condition, slope, and width of street crossings [
45]. Fuzzy logic was integrated with a PAM tool for locating the optimal pathways for wheelchair users, with findings suggesting that these users prioritize accessibility and comfort over short-distance travel [
11]. In a recent study, Tariah et al. [
46] evaluated mosque accessibility for wheelchair users in Riyadh by surveying 48 male wheelchair users. The findings revealed that participants regularly visiting the mosques faced significant accessibility issues in parking areas, which led to decreased social and religious engagement. Addressing broader mobility barriers, such as inclusive design for junctions/crossings and slopes, could improve mobility [
47,
48,
49].
With rapid advancements in wireless networks, GPS, and GIS technologies, analyzing and disseminating accessibility data has become much more manageable. These technologies aid PWD mobility by facilitating specialized applications and services. However, existing navigation systems often lack critical information on pedestrian pathway accessibility, such as sidewalk gradients and curb ramps. An informed pathway selection for IMAs is possible when accurate pathway data, including obstacle and gradient information, is available [
50].
MCDA is among the widely analytic approaches for evaluating the accessibility of pedestrians to transportation facilities. Manzolli et al. [
51] and Trolese et al. [
52] employed MCDA to examine the pedestrian walkability index. Manzolli evaluated walkability in Lisbon, ranking streets using the PROMETHEE method, while Trolese developed a data-driven walkability index for streets near urban hubs in Milan, Itlay. Weights assigned to each criterion under MCDA can profoundly influence the process of efficient pathway selection for PWD [
53]. A recent study by Gharebaghi et al. (2020) utilized a Fuzzy approach for IMAs-specific pathway planning [
12]. It was revealed that IMAs prioritize their pathways based on slopes, sidewalk conditions, and pavement surface conditions. Nosal and Solecka used MCDA and ranking methods for analyzing the accessibility of public transport by IMAs under complex urban environments [
54].
AHP is another widely used tool for wheelchair users’ pathway choice selection as a function of various factors, including slope, surface quality, and slope. In their study, Kasems and Karimi [
10] developed an AHP-based model using three weighting techniques to account for PWD-specific sidewalk needs in urban areas. The author highlighted the importance of pathway accessibility modeling. In other recent studies, the researchers’ impedance indices were used to evaluate the pathway accessibility for IMAs [
7,
55]. The proposed analytic framework was applied to the Canberra Road network in Singapore. Although the framework could effectively assess the adequacy of pedestrian infrastructure, it does not fully address the unique needs of PWD users in complex urban settings. Alzouby et al. [
22] suggested applying an integrated framework consisting of MCDA and AHP to analyze the accessibility of IMAs in Jordan. Findings revealed that a large portion (52%) of streets provide poor accessibility for IMAs.
One main challenge in determining pedestrian accessibility is the lack of reliable sidewalk and crossing data [
56]. In their study, Froehlich et al. [
57] comprehensively identified municipalities’ issues in managing accessibility data. Henje et al. [
58] studied the physical barriers wheelchair users face during urban commutes and reported that uneven road surfaces and steep gradients are the primary concerns. Ugalde et al. [
59] proposed an interesting novel framework consisting of subjective evaluation and mathematical models to identify the optimal road for IMAs. Key factors were considered, including road type, width, and pathway slope. Ntakolia et al. [
60] proposed a pathway optimization framework based on nonlinear programming, considering various optimization objectives such as safety, comfort, and touring experience of IMAs. Załuska et al. [
61] investigated factors influencing the travel preferences of IMA in four European countries, including Cyprus, Poland, Portugal, and Greece. Results revealed that travel decisions among IMAs are influenced by factors such as gender, country of origin, and type of disability.
Table 1 summarizes existing studies on route selection, planning, and optimization for IMAs. The table contained detailed information on various aspects such as study theme, geographic jurisdiction, type of disabilities and mobility aid used, accessibility barriers considered, analytic method, and key findings. GIS-based studies [
9,
50,
62,
63] primarily evaluate the routes based on the physical data. Experimental and simulations-based studies [
61,
64,
65] capture the users’ responses to control scenarios, which might not be practical for actual applications
Proposing a comprehensive disability-inclusive framework for IMAs’ accessibility warrants consideration of driver’s criteria, such as user socio-demographics of transport services and infrastructure. Integrating GIS and fuzzy logic with MCDA effectively improves accessibility gaps and priority areas for disabled users [
63]. Although few studies have developed an understanding of the dynamics of urban accessibility for wheelchair users, more research is needed to evaluate the efficacy of these analytics approaches in the context of developing countries, including Saudi Arabia.
Most of the studies in
Table 1 evaluated the routes for disabled persons in developed countries using sidewalk quality and slope as the primary evaluation criteria. In most countries, traffic control signals at the junctions are well-equipped for IMAs crossing. Considering the common urban road infrastructure conditions in Saudi Arabia, the present study included pathway length, slope, availability of sidewalks, and number of junctions to evaluate the adequacy of pathways for IMAs. To the authors’ knowledge, estimating the importance of criteria based on the user’s opinion has not been adequate. The present investigation adopted the PROMETHEE II method with complete and partial outranking with obvious merit over commonly used distance-based multi-criteria analysis methods, such as TOPSIS [
66], with its abilities to deal with different units without normalization step and partial ranking providing more flexibility to the decision-makers for trade-off on various criteria.
Table 1.
Summary of previous studies on route planning and optimization for PWDs.
Table 1.
Summary of previous studies on route planning and optimization for PWDs.
Study Theme | Country | Disability/Mobility Aid | Accessibility Criterion | Method Used | Key Findings | Reference |
---|
Mapping for Wheelchair Users: Route Navigation in Urban Spaces | UK | Physical disabilities /wheelchair | Surface type, route slope, surface curb types | GIS-based route modeling and optimization | Tailored maps for IWDs provided to improve their urban navigation | [9] |
User-Specific Web-Based Route Planning | Austria | Visual and physical disabilities | Sidewalk obstacles | User profile-driven route optimization algorithm | Proposed framework could improve the efficiency of route planning | [67] |
Simulating and Visualizing Sidewalk Accessibility for Wayfinding | USA | Physical disabilities/different mobility aids | Sidewalks and crosswalks feature, route, slope, curb surface type | Simulation | The proposed heat maps improved the understanding of the built environment for IWDs and enhanced their navigation | [64] |
The Route Planning Services Approach for People with Disability | Russia | Physical disabilities | Various pathway features, such as steps, ramps, slopes, and crossings | GraphHopper | Suggested customized routing for IWDs supports independence and convenience in urban commutes | [68] |
Development of Route Accessibility Index to Support Wayfinding for People with Disabilities | USA | Physical disabilities/ power and manual wheelchair | Curb ramps, path width, sidewalk slopes | Development of customized Route Accessibility Index | Proposed accessibility indicators optimize route planning and navigation | [68] |
Utility of a Mobile Route Planning App for People Aging with Disability | USA | Visual and physical disabilities | Sidewalk conditions, curb cuts, slopes | GIS-based route optimization | User-friendly app design led to efficient route planning for the aging population with disabilities | [62] |
Efficiently Informing Crowds—Experiments and Simulations on Route Choice and Decision Making in Pedestrian Crowds with Wheelchair Users | Japan | Physical disability/wheelchair | Exit type as wide, narrow, wide, sloped stairs | Experiments and simulation | Prioritization of information to wheelchairs enhances evacuation efficiency | [65] |
Personalized Accessible Wayfinding for People with Disabilities | USA | Physical disabilities/wheelchairs | Sidewalk quality, slope, width, compliance with standards | GIS-based assessment in compliance with ADA standards | Advanced wayfinding tools are expected to improve accessibility in the context of smart cities | [50] |
User-Specific Route Planning for People with Motor Disabilities: A Fuzzy Approach | Canada | Physical disabilities/ manual wheelchair | Sidewalk conditions, surface quality slopes | Fuzzy rule-based model | Personalized route planning is helpful to improve accessibility for wheelchair users | [12] |
Multiple-Stakeholder Perspectives on Accessibility Data and the Use of Socio-Technical Tools to Improve Sidewalk Accessibility | USA | Diverse disabilities/different mobility aids | Various sidewalk features, accessibility data needs | Project sidewalk tool and expert evaluation | Reliable data about infrastructure could help in route planning and the removal of accessibility barriers | [56] |
5. Discussion
This study aimed to evaluate and rank urban pathways based on their accessibility and convenience for IMAs across three cities in Saudi Arabia. Combining FSE and PROMETHEE II, a robust multi-criteria decision-making framework offers rankings of considered pathways based on IMAs’ perception. The selected pathways are evaluated for IMAs based on four primary criteria, including pathway length, number of junctions, percentage of the pathway length with footpaths, and slope of the road. The study found length to be the most critical concern of IMAs while commuting to public places for shopping, education, work, and other social activities. Around 65% of the participants considered length a high or very high-importance criterion. It is intuitive to have lower satisfaction scores for IMAs with mobility aids over longer pathways because it will increase strain and physical fatigue and expose them to unprotected crossings and uneven terrain, which can significantly reduce accessibility, particularly for older IMAs. These findings agree with the results of past studies [
16,
76]. The pathway length becomes critical for the individuals using artificial limbs and manual wheelchairs, 65% of the participants in this study. An efficient urban design incorporating mix-use development with commercial and recreational facilities, shorter paths to important (cultural, educational, and religious) locations with minimal detours, wide and maintained (smooth) sidewalks and ramps, and broad curb cuts for easy wheelchair access can minimize the impact of pathway length in a compute, supporting IMAs [
77].
The present survey’s results highlight the slope of the pathway as the second most critical criterion when around 67% of participants considered it of medium to very high importance. Steep slopes on urban roads are a significant barrier, particularly for manual mobility aids. It is reasonable for pathways with steep gradients to have lower satisfaction ratings since navigating steep uphill slopes requires substantial efforts to traverse through and frequently poses a higher risk of wheelchair tipping. Steeper gradients are particularly problematic for manual wheelchair users and elderly IMAs. As per the Americans with Disabilities Act (ADA), footpaths with slopes steeper than 5% (target value) require excessive PWD effort, leading to high fatigue and dependability [
78]. Around 70% of the pathways in the study area have slopes steeper than the target value. A recent study by Bakhsh et al. highlighted the varying challenging slopes in five parks of Hail City, i.e., one of the study regions in the present study [
79]. These findings direct towards considering slope as a significant constraint in urban infrastructure design in Saudi Arabia. Further, the findings highlight the importance of maintaining gentle slopes on frequently traveled urban pathways surrounding residential and busy commercial areas to promote safety and equity of travel for IMAs.
The length of footpaths along the pathway has been identified by ~69% of the participants as a critical barrier to their satisfaction with urban infrastructure. Longer sections of a pathway without a footpath increase the likelihood of accidents for IMAs, leading to injuries; IMAs using wheelchairs are more susceptible to such risks [
80,
81]. Consistent, well-designed, and separate pathways from vehicular traffic are expected to have higher satisfaction ratings of IMAs with mobility aids (wheelchairs) since they contribute to increased ride comfort and safety. In addition to the presence of sidewalks, other factors, including their width, surface quality, and obstacle-free access, are the critical pathway accessibility ranking by IMAs [
82,
83]. Per the Built Environment Guidelines prepared by the Prince Salman Center of Disability Research (PSCDR) in Saudi Arabia [
84], a curb cut should have smooth transitions and minimal slope and be identified with detectable (textured) surfaces to avoid balance problems due to flared edges. PSCDR also recommended a minimum clear width of the footpath of 1.8 m to help with the movability of wheelchairs and scooters. Apart from design constraints, the promulgation of the law can also minimize wrong parking on footpaths and excessive growth of trees and bushes partially covering footpath space, impeding movement of IMAs more than a walking pedestrian [
85]. The findings indicate the importance of providing continuous and well-designed sidewalks to ensure the smooth accessibility and safety of vulnerable IMA groups.
Almost half the participants identified the number of junctions as the least important than the above-stated criteria. Nevertheless, crossing decision is a significant risk factor associated with the safety of IMAs [
86], particularly in the absence of a properly designed and equipped traffic control signal. Excluding busy downtowns, the chance of facing inadequately designed or equipped junctions increases with an increase in the number of junctions. Urban pathways with several junctions to be traversed will likely have lower satisfaction scores since wheelchair users face challenges such as frequent stops, constant attention to traffic, and traveling through uneven surfaces, particularly in the absence of ramps. According to PSCDR [
84] pedestrian signals should have 100 mm colored push buttons highlighted in surroundings and mounted at 0.9 m to 1.2 m above the ground. In addition, raised crossings with 0.6 m truncated domes with warning surfaces also facilitate IMAs. More details on the design can be found in PSCDR (2010) [
87]. Thus, it is crucial to minimize the number of junctions or incorporate smart crosswalk aids/technologies that will facilitate smooth and safe crosswalk travel.
Based on the study’s findings, several policy implications may be considered for promoting a disability-inclusive urban transportation system. It is apparent from the study’s findings that the demographics of IMAs play a vital role in their travel decision and pathway selection. Hence, urban transport planning should consider the diverse needs of IMAs, socioeconomic factors, and different types of disabilities. Similarly, policies should consider the provision of continuous sidewalks, adequately designed with gentle slopes and reasonable widths and ramps at entry and exit locations. The number of road crossings should be reduced as much as possible, and intelligent adaptive crossings should be implemented where mandatory. It is also essential to establish and monitor protocols for periodic inspection and retrofitting of infrastructure to ensure sustained accessibility for all residents. Finally, awareness and education among the public regarding an inclusive urban design will ensure the safe and smooth participation of IMAs in the urban economy.