Quantifying the Risk Impact of Contextual Factors on Pedestrian Crash Outcomes in Data-Scarce Developing Country Settings
Abstract
1. Introduction
- Extracting trend data of contextual factors from literature sources.
- Generating a representative artificial dataset based on ranges and distributions reported in the literature, with outputs visualised as histograms and boxplots.
- External face validity checks of the generated data.
- Estimating the relative influence value (Fi) of each factor on crash frequency through pairwise correlation, stepwise regression, and transformation of regression coefficients.
- Performing sensitivity analysis and Fi uncertainty check.
- Mapping regression outputs with iRAP’s pedestrian crash risk framework to identify potential gaps.
2. Materials and Methods
2.1. Data Collection and Factor Selection
2.2. Extracting Trend Data of Each Factor from Literature Sources
2.3. Artificial Data Generation
- Using NumPy to generate 2000 random artificial data values for each variable. NumPy’s random number capabilities are widely used in scientific computing for simulation and statistical modelling tasks [14].
- To ensure statistical reliability, truncated normal distributions were applied on continuous variables to generate random numbers using SciPy’s truncnorm function [15]. This ensured that all values fall within the literature-derived minimum and maximum range while approximating the specified mean and standard deviation [16].
- Random binary distribution was used for categorical/binary variables based on the reported mean values. This is equivalent to a Bernoulli random distribution [17].
- The generated values were normalised and rescaled to have nearly the same mean and standard deviation using Pandas [18].
- Histograms and boxplots were generated using Matplotlib to visually verify variable distributions [19].
2.4. External Face Validity and Dependence of Generated Data
2.5. Estimating the Influence of Risk Factors on Pedestrian Crash Outcomes
2.5.1. Correlation Analyses
- Ranked the values of the independent variable (X) across all the 2000 random observations. Replaced each row value for the variable with their corresponding ranks.
- Ranked the fatal pedestrian crash counts/dependent variable (Y) across 2000 random observations.
- Calculated the Spearman’s correlation coefficient between the two ranked pairs of variables using the following correlation formula:
- ρ is the Spearman correlation coefficient;
- di is the difference in ranks between the two variables (e.g., di = rank(Xi)—rank(Yi));
- n is the number of observations (where n = 2000).
2.5.2. Stepwise Regression Modelling
- Model 1: Constant only (baseline);
- Model 2: Traffic exposure and operational variables (e.g., mixed traffic conditions);
- Model 3: Land use and planning variables (e.g., road use);
- Model 4: Demographics (e.g., age group);
- Model 5: Infrastructure and roadway variables (e.g., coverage of pedestrian infrastructure);
- Model 6: Full model (combined all variables).
- yi is the expected number of crashes/crash count at point i.
- X1i, X2i, ….: independent/predictor variables.
- β0, β2, …: coefficients estimated by maximum likelihood.
- Restricted log-likelihood () of the null (intercept-only) model;
- McFadden’s Pseudo-R2 static/log-likelihood ratio index (ρ2) given by:
- Akaike Information Criterion (AIC), which is given as:
2.5.3. Transforming NB Coefficients into Risk Factor Influence Values (Fi)
2.6. Sensitivity Analysis and Fi Uncertainty
- Bootstrap resampling: 1000 bootstrap samples of the synthetic dataset were drawn with replacement. For each bootstrap, negative binomial (NB) models were re-estimated and Fi values recalculated. This allowed the derivation of 95% confidence intervals.
- Scenario perturbation: The synthetic dataset was resampled under varying sample sizes (n = 1000; 2000; 5000) and with multiplicative noise applied to predictor variables (5% and 10%). For each scenario, Fi values were recalculated, and stability of variable rankings was assessed using Kendall’s τ correlation with baseline rankings.
2.7. Comparative Analyses (Mapping of Factors to NB Model and iRAP Framework)
| Characteristics | Variables | Variable Type | Minimum | Maximum | Mean (μ) | Standard Deviation (δ) | References | Country |
|---|---|---|---|---|---|---|---|---|
| Safety Performance | Fatal Pedestrian Crash Statistics | Continuous | 0.00 | 13.00 | 1.83 | 2.29 | [10] | India |
| Traffic Exposures and Operational Characteristics | Log (Average Daily Traffic Volume) | Continous | 4.24 | 5.47 | 4.71 | 0.22 | [10] | India |
| Log (Average Daily Pedestrian Volume) | Continuous | 3.33 | 5.25 | 4.58 | 0.35 | [10] | India | |
| Speed (km/h) | Continuous | 30.00 | 65.00 | 42.48 | 9.38 | [10] | India | |
| Pedestrian to Vehicle Volume Ratio/Mixed Traffic Conditions | Continuous | 0.05 | 9.20 | 1.09 | 1.23 | [10] | India | |
| Vehicle age/technology (%) | Continuous | 0.50 | 0.90 | 0.70 | 0.13 | [29] | Nigeria, Ghana, Ethiopia, Kenya | |
| Compliance/Presence of Overtaking Tendency of Vehicle (1/0) | Categorical | 0.00 | 1.00 | 0.67 | 0.48 | [10] | India | |
| Enforcement of Traffic rules (Yes = 1; No = 0) | Categorical | 0.00 | 1.00 | 0.50 | 0.50 | [10,30] | India | |
| Public safety awareness level (%) | Continuous | 0.31 | 0.68 | 0.50 | 0.13 | [31] | Bangladesh | |
| Driver safety awareness level (%) | Continuous | 0.38 | 0.54 | 0.48 | 0.13 | [32] | Quatar | |
| Time of the Day (visibility) (1/0) | Categorical | 0.00 | 1.00 | 0.49 | 0.50 | [33] | India | |
| Land use and Planning | Hierarchical Road Classification/Road Use (%) | Continuous | 0.16 | 0.80 | 0.45 | 0.20 | [34] | Brazil, Columbia, Tanzania |
| Design Configuration (%) | Continuous | 0.10 | 0.55 | 0.30 | 0.15 | [35,36,37] | Ethiopia, India | |
| Ad hoc implementation of countermeasures (%) | Continuous | 0.60 | 0.90 | 0.75 | 0.10 | [38,39,40,41] | Uganda, India, Ghana | |
| Encroachment of Footpath by Street vendors (%) | Continuous | 0.00 | 1.00 | 0.61 | 0.36 | [10] | India | |
| Human Capacity of responsible agencies (Adequate = 1, Poor = 0) | Categorical | 0.00 | 1.00 | 0.50 | 0.30 | [42] | World Bank | |
| Demographics | Age group (%) | Below 18 years (%) | 0.00 | 0.90 | 0.09 | 0.15 | [33] | India |
| 18–49 years (in %) | 0.06 | 1.00 | 0.79 | 0.15 | [33] | India | ||
| 50+ years (%) | 0.00 | 0.33 | 0.11 | 0.07 | [33] | India | ||
| Gender (%) | Male pedestrians (%) | 0.02 | 0.90 | 0.73 | 0.15 | [33] | India | |
| Female (%) | 0.11 | 0.35 | 0.23 | 0.12 | [43] | USA | ||
| Employed population (%) | Continuous | 0.40 | 0.70 | 0.55 | 0.10 | [44] | World Bank | |
| Infrastructure and Roadway Factors | Maintenance Practices/level (%) | Continuous | 0.05 | 0.40 | 0.20 | 0.10 | [35,36] | Ghana and Ethiopia |
| Coverage of pedestrian infrastructure (%) | Continuous | 0.20 | 0.60 | 0.40 | 0.10 | [41] | India | |
| Vandalism of Street Furniture (Never = 1; Sometimes = 0.5; Always = 0) | Categorical | 0.00 | 1.00 | 0.70 | 0.20 | [45] | Turkey | |
| Age of the countermeasure (years) | Continuous | 0.50 | 10.00 | 5.00 | 2.50 | [46] | USA | |
| Appropriate location of countermeasure (1/0) | Categorical | 0.00 | 1.00 | 0.60 | 0.20 | [37] | Ethiopia |
| Characteristics | Variables | Variable Type | Minimum | Maximum | Mean (μ) | Median | Standard Deviation (δ) | StdErr | 95% CI Lower Bound | 95% CI Upper Bound |
|---|---|---|---|---|---|---|---|---|---|---|
| Safety Performance | Fatal Pedestrian Crash Statistics | Continuous | 0.00 | 10.67 | 2.03 | 1.50 | 2.06 | 0.05 | 1.94 | 2.12 |
| Traffic Exposures and Operational Characteristics | Log (Average Daily Traffic Volume) | Continuous | 4.24 | 5.47 | 4.71 | 4.71 | 0.22 | 0.00 | 4.70 | 4.72 |
| Log (Average Daily Pedestrian Volume) | Continuous | 3.37 | 5.25 | 4.58 | 4.59 | 0.35 | 0.01 | 4.56 | 4.59 | |
| Speed (km/h) | Continuous | 30.00 | 65.00 | 42.67 | 42.00 | 9.06 | 0.20 | 42.27 | 43.06 | |
| Pedestrian to Vehicle Volume Ratio/Mixed Traffic Conditions | Continuous | 0.05 | 6.07 | 1.19 | 0.95 | 1.11 | 0.02 | 1.14 | 1.24 | |
| Vehicle age/technology (%) | Continuous | 0.50 | 0.90 | 0.70 | 0.70 | 0.12 | 0.00 | 0.69 | 0.71 | |
| Compliance/Presence of Overtaking Tendency of Vehicle (1/0) | Categorical | 0.00 | 1.00 | 0.66 | 1.00 | 0.48 | 0.01 | 0.63 | 0.68 | |
| Enforcement of Traffic rules (Yes = 1; No = 0) | Categorical | 0.00 | 1.00 | 0.51 | 1.00 | 0.50 | 0.01 | 0.48 | 0.53 | |
| Public safety awareness level (%) | Continuous | 0.31 | 0.68 | 0.50 | 0.50 | 0.12 | 0.00 | 0.49 | 0.51 | |
| Driver safety awareness level (%) | Continuous | 0.38 | 0.54 | 0.47 | 0.49 | 0.07 | 0.00 | 0.47 | 0.47 | |
| Time of the Day (visibility) (1/0) | Categorical | 0.00 | 1.00 | 0.48 | 0.00 | 0.50 | 0.01 | 0.46 | 0.50 | |
| Land use and Planning | Hierarchical Road Classification/Road Use (%) | Continuous | 0.16 | 0.80 | 0.45 | 0.44 | 0.19 | 0.00 | 0.44 | 0.46 |
| Design Configuration (%) | Continuous | 0.10 | 0.55 | 0.30 | 0.29 | 0.14 | 0.00 | 0.30 | 0.31 | |
| Ad hoc implementation of countermeasures (%) | Continuous | 0.60 | 0.90 | 0.75 | 0.75 | 0.09 | 0.00 | 0.75 | 0.75 | |
| Encroachment of Footpath by Street vendors (%) | Continuous | 0.00 | 1.00 | 0.60 | 0.64 | 0.32 | 0.01 | 0.58 | 0.61 | |
| Human Capacity of responsible agencies (Adequate = 1, Poor = 0) | Categorical | 0.00 | 1.00 | 0.50 | 0.00 | 0.50 | 0.01 | 0.48 | 0.52 | |
| Demographics | Age group (%) | Below 18 years (%) | 0.00 | 0.69 | 0.11 | 0.07 | 0.13 | 0.00 | 0.10 | 0.12 |
| 18–49 years (in %) | 0.21 | 1.00 | 0.79 | 0.80 | 0.15 | 0.00 | 0.78 | 0.79 | ||
| 50+ years (%) | 0.00 | 0.33 | 0.11 | 0.10 | 0.07 | 0.00 | 0.11 | 0.11 | ||
| Gender (%) | Male pedestrians (%) | 0.13 | 0.90 | 0.72 | 0.74 | 0.14 | 0.00 | 0.72 | 0.73 | |
| Female (%) | 0.11 | 0.35 | 0.23 | 0.23 | 0.09 | 0.00 | 0.23 | 0.23 | ||
| Employed population (%) | Continuous | 0.40 | 0.70 | 0.55 | 0.55 | 0.09 | 0.00 | 0.55 | 0.55 | |
| Infrastructure and Roadway Factors | Maintenance Practices/level (%) | Continuous | 0.05 | 0.40 | 0.20 | 0.20 | 0.10 | 0.00 | 0.20 | 0.21 |
| Coverage of pedestrian infrastructure (%) | Continuous | 0.20 | 0.60 | 0.40 | 0.40 | 0.10 | 0.00 | 0.40 | 0.40 | |
| Vandalism of Street Furniture (Never = 1; Sometimes = 0.5; Always = 0) | Categorical | 0.00 | 1.00 | 0.70 | 1.00 | 0.46 | 0.01 | 0.68 | 0.72 | |
| Age of the countermeasure (years) | Continuous | 0.50 | 10.00 | 5.01 | 5.04 | 2.47 | 0.06 | 4.90 | 5.12 | |
| Appropriate location of countermeasure (1/0) | Categorical | 0.00 | 1.00 | 0.61 | 1.00 | 0.49 | 0.01 | 0.59 | 0.63 |
| Variable | Min | Max | Mean | Std Dev | Spearman Rho | T-Statistic | p-Value |
|---|---|---|---|---|---|---|---|
| Log Average Daily Traffic Volume | 4.240 | 5.470 | 4.710 | 0.220 | −0.029 | −1.285 | 0.199 |
| Log Average Daily Pedestrian Volume | 3.364 | 5.250 | 4.580 | 0.349 | 0.030 | 1.336 | 0.182 |
| Speed (km/h) | 30.000 | 65.000 | 42.697 | 8.988 | 0.029 | 1.282 | 0.200 |
| Pedestrian to Vehicle Volume Ratio | 0.050 | 6.087 | 1.179 | 1.128 | 0.000 | 0.010 | 0.992 |
| Vehicle age technology (%) | 0.500 | 0.900 | 0.700 | 0.122 | 0.003 | 0.124 | 0.901 |
| Overtaking Tendency (1/0) | 0.000 | 1.000 | 0.668 | 0.471 | −0.037 | −1.662 | 0.097 |
| Traffic Rule Enforcement (1/0) | 0.000 | 1.000 | 0.517 | 0.500 | 0.009 | 0.387 | 0.699 |
| Public Safety Awareness (%) | 0.310 | 0.680 | 0.499 | 0.119 | −0.026 | −1.161 | 0.246 |
| Driver Safety Awareness (%) | 0.380 | 0.540 | 0.468 | 0.069 | 0.017 | 0.755 | 0.450 |
| Time of Day Visibility (1/0) | 0.000 | 1.000 | 0.491 | 0.500 | 0.011 | 0.490 | 0.624 |
| Road Use (%) | 0.160 | 0.800 | 0.452 | 0.191 | 0.001 | 0.039 | 0.969 |
| Design Configuration (%) | 0.100 | 0.550 | 0.302 | 0.139 | 0.018 | 0.791 | 0.429 |
| Ad hoc implementation of countermeasures (%) | 0.600 | 0.900 | 0.751 | 0.094 | −0.032 | −1.407 | 0.160 |
| Footpath Encroachment (%) | 0.000 | 1.000 | 0.596 | 0.326 | 0.008 | 0.342 | 0.733 |
| Human Capacity of Agencies (1/0) | 0.000 | 1.000 | 0.498 | 0.500 | 0.013 | 0.581 | 0.562 |
| Age < 18 (%) | 0.000 | 0.685 | 0.111 | 0.128 | −0.021 | −0.926 | 0.355 |
| Age 18–49 (%) | 0.181 | 1.000 | 0.788 | 0.147 | 0.031 | 1.373 | 0.170 |
| Age 50+ (%) | 0.000 | 0.330 | 0.111 | 0.069 | −0.011 | −0.487 | 0.627 |
| Male Pedestrians (%) | 0.158 | 0.900 | 0.725 | 0.143 | 0.036 | 1.616 | 0.106 |
| Female Pedestrians (%) | 0.110 | 0.350 | 0.230 | 0.092 | −0.023 | −1.016 | 0.310 |
| Employed Population (%) | 0.400 | 0.700 | 0.550 | 0.094 | 0.021 | 0.947 | 0.344 |
| Maintenance Practices (%) | 0.050 | 0.400 | 0.201 | 0.097 | −0.006 | −0.251 | 0.802 |
| Pedestrian Infrastructure Coverage (%) | 0.200 | 0.600 | 0.400 | 0.099 | 0.008 | 0.374 | 0.709 |
| Street Furniture Vandalism (0/0.5/1) | 0.000 | 1.000 | 0.680 | 0.467 | −0.024 | −1.074 | 0.283 |
| Age of Countermeasure years | 0.500 | 10.000 | 5.006 | 2.466 | −0.022 | −0.968 | 0.333 |
| Appropriate Countermeasure Location (1/0) | 0.000 | 1.000 | 0.608 | 0.488 | 0.033 | 1.468 | 0.142 |
| FT | T | P | S | R | VAT | OT | TR | PSA | DSA | TD | RU | DC | CA | FE | HCA | AG1 | AG2 | AG3 | MP | FP | EP | MTP | PIC | SFV | AC | ACL | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FT | 1.000 | ||||||||||||||||||||||||||
| T | −0.029 | 1.000 | |||||||||||||||||||||||||
| P | 0.030 | 0.004 | 1.000 | ||||||||||||||||||||||||
| S | 0.029 | −0.021 | −0.019 | 1.000 | |||||||||||||||||||||||
| R | 0.000 | −0.038 | 0.005 | 0.017 | 1.000 | ||||||||||||||||||||||
| VAT | 0.003 | −0.005 | 0.013 | −0.013 | −0.033 | 1.000 | |||||||||||||||||||||
| OT | −0.037 | 0.017 | −0.001 | −0.023 | −0.011 | 0.018 | 1.000 | ||||||||||||||||||||
| TR | 0.009 | 0.003 | −0.075 | 0.019 | −0.030 | −0.034 | 0.009 | 1.000 | |||||||||||||||||||
| PSA | −0.026 | 0.025 | −0.002 | 0.018 | 0.019 | −0.039 | 0.063 | 0.006 | 1.000 | ||||||||||||||||||
| DSA | 0.017 | 0.031 | 0.013 | 0.003 | 0.004 | −0.001 | 0.003 | −0.025 | 0.006 | 1.000 | |||||||||||||||||
| TD | 0.011 | 0.012 | −0.007 | 0.001 | 0.018 | 0.024 | 0.054 | −0.016 | 0.007 | −0.005 | 1.000 | ||||||||||||||||
| RU | 0.001 | 0.001 | −0.016 | 0.018 | 0.025 | 0.016 | −0.013 | 0.015 | 0.015 | 0.021 | −0.017 | 1.000 | |||||||||||||||
| DC | 0.018 | 0.017 | 0.004 | −0.003 | −0.003 | −0.028 | −0.009 | 0.002 | 0.004 | −0.013 | −0.020 | 0.014 | 1.000 | ||||||||||||||
| CA | −0.031 | 0.026 | −0.005 | −0.024 | 0.011 | 0.001 | 0.021 | −0.047 | 0.011 | 0.000 | 0.001 | 0.017 | −0.025 | 1.000 | |||||||||||||
| FE | 0.008 | −0.011 | −0.017 | 0.017 | 0.012 | 0.000 | 0.009 | −0.003 | −0.023 | 0.027 | 0.018 | 0.011 | 0.022 | 0.056 | 1.000 | ||||||||||||
| HCA | 0.013 | −0.006 | 0.034 | 0.033 | 0.021 | 0.019 | −0.011 | −0.008 | −0.009 | 0.004 | 0.005 | 0.025 | −0.008 | 0.009 | −0.009 | 1.000 | |||||||||||
| AG1 | −0.021 | 0.015 | −0.004 | 0.009 | −0.035 | −0.017 | −0.002 | −0.027 | 0.025 | 0.005 | −0.031 | 0.022 | 0.019 | 0.007 | 0.032 | −0.056 | 1.000 | ||||||||||
| AG2 | 0.031 | −0.025 | 0.025 | −0.010 | −0.003 | −0.014 | 0.002 | 0.029 | −0.007 | −0.001 | −0.001 | 0.019 | 0.003 | −0.021 | −0.029 | 0.017 | −0.017 | 1.000 | |||||||||
| AG3 | −0.011 | 0.012 | 0.004 | 0.010 | 0.023 | 0.023 | 0.019 | −0.043 | −0.013 | 0.008 | 0.027 | −0.002 | 0.008 | 0.021 | −0.008 | −0.004 | −0.022 | 0.033 | 1.000 | ||||||||
| MP | 0.036 | 0.005 | −0.002 | 0.011 | −0.027 | 0.020 | 0.070 | −0.021 | 0.019 | 0.036 | −0.036 | −0.015 | −0.035 | 0.026 | −0.004 | 0.005 | −0.003 | 0.025 | 0.043 | 1.000 | |||||||
| FP | −0.023 | 0.018 | −0.012 | −0.022 | 0.012 | 0.009 | −0.002 | −0.001 | 0.010 | 0.043 | −0.013 | −0.023 | 0.014 | −0.022 | 0.012 | −0.006 | 0.018 | 0.021 | −0.019 | 0.008 | 1.000 | ||||||
| EP | 0.021 | −0.017 | 0.030 | −0.005 | 0.012 | −0.021 | 0.016 | −0.020 | 0.018 | 0.008 | −0.002 | 0.015 | −0.009 | 0.002 | 0.007 | −0.005 | −0.058 | 0.026 | 0.001 | 0.013 | −0.017 | 1.000 | |||||
| MTP | −0.006 | −0.038 | −0.008 | −0.013 | 0.013 | −0.025 | −0.003 | −0.004 | 0.011 | 0.014 | 0.025 | 0.003 | −0.007 | 0.013 | −0.003 | 0.029 | 0.043 | −0.007 | −0.006 | 0.015 | −0.057 | 0.023 | 1.000 | ||||
| PIC | 0.008 | −0.012 | −0.043 | 0.012 | −0.040 | −0.019 | 0.008 | −0.038 | −0.045 | 0.029 | 0.001 | 0.013 | −0.004 | 0.003 | −0.002 | 0.023 | −0.007 | 0.019 | −0.036 | 0.012 | −0.052 | 0.021 | 0.022 | 1.000 | |||
| SFV | −0.024 | 0.054 | 0.001 | −0.018 | 0.020 | −0.004 | −0.034 | −0.019 | −0.026 | −0.040 | 0.027 | 0.010 | 0.003 | −0.007 | 0.011 | 0.030 | −0.005 | −0.023 | −0.008 | −0.026 | 0.016 | −0.013 | 0.001 | 0.009 | 1.000 | ||
| AC | −0.022 | −0.009 | −0.013 | 0.021 | −0.019 | −0.038 | 0.003 | −0.029 | −0.001 | −0.024 | 0.015 | −0.038 | 0.009 | 0.019 | 0.006 | −0.001 | −0.017 | −0.002 | −0.021 | 0.032 | −0.009 | 0.048 | −0.001 | −0.021 | −0.007 | 1.000 |
| Coefficient (β) | StdErr | z-Value | P > |z| | CI Lower | CI Upper | Variable | Model |
|---|---|---|---|---|---|---|---|
| 0.704 | 0.027 | 25.750 | 0.000 | 0.650 | 0.758 | intercept | Model_1_Baseline |
| 0.680 | 0.720 | 0.943 | 0.345 | −0.732 | 2.092 | const | Model_2_Traffic |
| −0.146 | 0.125 | −1.174 | 0.240 | −0.391 | 0.098 | Log Average Daily Traffic Volume | Model_2_Traffic |
| 0.109 | 0.078 | 1.393 | 0.164 | −0.045 | 0.263 | Log Average Daily Pedestrian Volume | Model_2_Traffic |
| 0.003 | 0.003 | 0.832 | 0.405 | −0.003 | 0.008 | Speed (km/h) | Model_2_Traffic |
| 0.004 | 0.024 | 0.150 | 0.881 | −0.044 | 0.051 | Pedestrian to Vehicle Volume Ratio | Model_2_Traffic |
| 0.142 | 0.224 | 0.635 | 0.526 | −0.296 | 0.580 | Vehicle age technology (%) | Model_2_Traffic |
| 1.018 | 0.239 | 4.262 | 0.000 | 0.550 | 1.486 | const | Model_3_Land_Use |
| 0.060 | 0.143 | 0.416 | 0.677 | −0.221 | 0.340 | Road Use (%) | Model_3_Land_Use |
| 0.112 | 0.196 | 0.569 | 0.569 | −0.273 | 0.497 | Design Configuration (%) | Model_3_Land_Use |
| −0.496 | 0.291 | −1.707 | 0.088 | −1.066 | 0.073 | Ad hoc implementation of countermeasures (%) | Model_3_Land_Use |
| −0.005 | 0.084 | −0.065 | 0.948 | −0.170 | 0.159 | Footpath Encroachment (%) | Model_3_Land_Use |
| 0.446 | 0.267 | 1.666 | 0.096 | −0.078 | 0.970 | const | Model_4_Demographic |
| 0.065 | 0.214 | 0.302 | 0.763 | −0.355 | 0.484 | Age < 18 (%) | Model_4_Demographic |
| 0.154 | 0.186 | 0.826 | 0.409 | −0.212 | 0.519 | Age 18–49 (%) | Model_4_Demographic |
| −0.073 | 0.398 | −0.183 | 0.854 | −0.852 | 0.706 | Age 50+ (%) | Model_4_Demographic |
| 0.088 | 0.192 | 0.460 | 0.645 | −0.288 | 0.464 | Male Pedestrians (%) | Model_4_Demographic |
| −0.140 | 0.298 | −0.468 | 0.639 | −0.724 | 0.445 | Female Pedestrians (%) | Model_4_Demographic |
| 0.191 | 0.292 | 0.655 | 0.512 | −0.381 | 0.764 | Employed Population (%) | Model_4_Demographic |
| 0.741 | 0.149 | 4.972 | 0.000 | 0.449 | 1.033 | const | Model_5_Infrastructure |
| −0.100 | 0.283 | −0.354 | 0.723 | −0.654 | 0.454 | Maintenance Practices (%) | Model_5_Infrastructure |
| 0.077 | 0.277 | 0.277 | 0.782 | −0.466 | 0.620 | Pedestrian Infrastructure Coverage (%) | Model_5_Infrastructure |
| −0.032 | 0.058 | −0.553 | 0.581 | −0.147 | 0.082 | Street Furniture Vandalism (0/0.5/1) | Model_5_Infrastructure |
| −0.011 | 0.011 | −0.961 | 0.336 | −0.032 | 0.011 | Age of Countermeasure (years) | Model_5_Infrastructure |
| 0.045 | 0.056 | 0.799 | 0.424 | −0.065 | 0.155 | Appropriate Countermeasure Location (1/0) | Model_5_Infrastructure |
| 0.765 | 0.819 | 0.934 | 0.350 | −0.840 | 2.369 | const | Model_6_Full |
| −0.145 | 0.125 | −1.159 | 0.247 | −0.391 | 0.100 | Log Average Daily Traffic Volume | Model_6_Full |
| 0.103 | 0.079 | 1.310 | 0.190 | −0.051 | 0.257 | Log Average Daily Pedestrian Volume | Model_6_Full |
| 0.002 | 0.003 | 0.802 | 0.423 | −0.004 | 0.008 | Speed (km/h) | Model_6_Full |
| 0.004 | 0.024 | 0.177 | 0.860 | −0.043 | 0.052 | Pedestrian to Vehicle Volume Ratio | Model_6_Full |
| 0.149 | 0.225 | 0.663 | 0.507 | −0.291 | 0.589 | Vehicle age technology (%) | Model_6_Full |
| 0.049 | 0.144 | 0.344 | 0.731 | −0.232 | 0.331 | Road Use (%) | Model_6_Full |
| 0.126 | 0.197 | 0.640 | 0.522 | −0.260 | 0.512 | Design Configuration (%) | Model_6_Full |
| −0.460 | 0.292 | −1.578 | 0.114 | −1.031 | 0.111 | Ad hoc implementation of countermeasures (%) | Model_6_Full |
| 0.000 | 0.084 | 0.002 | 0.998 | −0.165 | 0.165 | Footpath Encroachment (%) | Model_6_Full |
| 0.057 | 0.215 | 0.264 | 0.792 | −0.365 | 0.478 | Age < 18 (%) | Model_6_Full |
| 0.135 | 0.187 | 0.725 | 0.469 | −0.231 | 0.502 | Age 18–49 (%) | Model_6_Full |
| −0.083 | 0.399 | −0.208 | 0.835 | −0.864 | 0.698 | Age 50+ (%) | Model_6_Full |
| 0.109 | 0.193 | 0.568 | 0.570 | −0.268 | 0.487 | Male Pedestrians (%) | Model_6_Full |
| −0.152 | 0.300 | −0.507 | 0.612 | −0.740 | 0.436 | Female Pedestrians (%) | Model_6_Full |
| 0.203 | 0.293 | 0.691 | 0.490 | −0.372 | 0.777 | Employed Population (%) | Model_6_Full |
| −0.116 | 0.284 | −0.408 | 0.683 | −0.672 | 0.441 | Maintenance Practices (%) | Model_6_Full |
| 0.056 | 0.279 | 0.202 | 0.840 | −0.490 | 0.603 | Pedestrian Infrastructure Coverage (%) | Model_6_Full |
| −0.026 | 0.059 | −0.447 | 0.655 | −0.141 | 0.089 | Street Furniture Vandalism (0/0.5/1) | Model_6_Full |
| −0.010 | 0.011 | −0.920 | 0.358 | −0.032 | 0.012 | Age of Countermeasure years | Model_6_Full |
| 0.047 | 0.056 | 0.832 | 0.406 | −0.064 | 0.157 | Appropriate Countermeasure Location (1/0) | Model_6_Full |
| Model | No. of Parameters Included (K) | No of Observations (n) | LLmodel | LLnull | McFadden’s Pseudo-R2 | AIC |
|---|---|---|---|---|---|---|
| Model 1 (Baseline) | 1 | 2000 | −3846.554 | −3846.554 | 0.000000 | 7695.108 |
| Model 2 (Traffic exposure and operational variables) | 6 | 2000 | −3846.077 | −3846.554 | 0.000124 | 7704.153 |
| Model 3 (Land use and planning variables) | 5 | 2000 | −3845.035 | −3846.554 | 0.000395 | 7700.07 |
| Model 4 (Demographic variables) | 7 | 2000 | −3844.866 | −3846.554 | 0.000439 | 7703.732 |
| Model 5 (Infrastructure and roadway variables) | 6 | 2000 | −3844.559 | −3846.554 | 0.000519 | 7701.119 |
| Model 6 (Full model) | 21 | 2000 | −3840.842 | −3846.554 | 0.001485 | 7723.683 |
3. Results
3.1. Distribution of Trend Data and Artificial Datasets for Each Factor
3.2. External Face Validity of Generated Data
3.3. Correlation Analysis
3.4. Regression Analysis (Negative Binomial Models)
3.5. Transforming NB Coefficients into Risk Factor Influence Values (Fi)
- Ad hoc implementation of countermeasures had a risk factor value of 0.63, indicating a 37% reduction in expected safety benefits when countermeasures are implemented after an accident has happened rather than before.
- Female pedestrians had a risk factor value of 0.86, reinforcing gender-specific vulnerability that remains unaddressed in current global frameworks.
- Employed population (1.22), and age 18–49 (1.15) showed the highest positive risk values among demographic variables. These highlight that areas with a high concentration of working-age pedestrians face elevated pedestrian crash risks, even when standard countermeasures are applied.
- Vehicle age/technology (1.16) also exhibited an elevated risk value, pointing to the indirect effects of outdated or poorly maintained vehicle fleets, another non-iRAP parameter.
- Design configuration (1.14) and road use (1.05), both geometric variables already covered in iRAP, showed moderate risk increases. However, their explanatory power appeared weaker compared to social–behavioural and institutional variables.
3.6. Sensitivity Analysis
3.7. Comparative Analysis with iRAP Framework (Mapping of Factors to NB Model and iRAP Framework)
4. Discussion
4.1. External Face Validity
4.2. Correlation and Regression Analysis
4.3. Sensitivity Analysis
4.4. Mapping to iRAP
4.5. Methodological Contributions
5. Limitations
6. Conclusions
7. Recommendations
- Integration with existing frameworksArtificial-data modelling should be used to complement established tools such as iRAP by incorporating contextual factors absent from current models, including institutional capacity, enforcement, and safety awareness. This would enhance the predictive sensitivity of safety assessments in developing countries.
- Empirical calibration and validationFuture research should apply this methodology to real-world crash datasets as they become available. Such empirical calibration will be essential to refine Fi estimates and validate the robustness of artificial-data models.
- Refinement of sensitivity approachesSensitivity testing should be expanded to include alternative approaches, such as Bayesian inference or hierarchical modelling, which may capture uncertainty more comprehensively in data-scarce environments.
- Application to enhanced effectiveness modellingThe Fi values derived here, alongside weighting schemes developed in subsequent research, should inform the construction of an enhanced iRAP effectiveness model. This has the potential to address the performance gap identified in earlier reviews and improve the targeting of countermeasures in developing countries.
- Policy and practicePolicymakers and practitioners should recognise that behavioural and institutional interventions such as sustained enforcement, awareness campaigns, and investment in agency capacity may yield equal or greater safety benefits than infrastructure redesign alone.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
| AIC | Akaike Information Criterion |
| CI | Confidence Interval |
| DC | Developing Country |
| GLM | Generalised Linear Model |
| HIC | High-Income Country |
| IDE | Integrated Development Environment |
| iRAP | International Road Assessment Programme |
| IRR | Incident Rate Ratios |
| KDE | Kernel Density Estimation |
| LMIC | Low- and Middle-Income Countries |
| NB | Negative Binomial |
| SLR | Systematic Literature Review |
| WHO | World Health Organisation |
Appendix A. Python Code for Generating Artificial Data for All the Variables






Appendix B. Histograms and Boxplots Showing Distribution for Various Variables












Appendix C. Python Scripts for Spearman’s Correlation, Negative Binomial Modelling with Model Fit Metrics





Appendix D. Python Code for Sensitivity Analysis and Fi Uncertainty Check





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| Variable/Factor | NB Coefficient (β) | Risk Factor Influence (Fi) = eβ | Bootstrap 95% Confidence Interval for Fi | ||
|---|---|---|---|---|---|
| Lower Bound (2.5th Percentile) | Median (50th Percentile) | Upper Bound (97.5th Percentile) | |||
| Log (Avg Daily Traffic Volume) | −0.150 | 0.86 | 0.910 | 1.126 | 1.380 |
| Log (Avg Daily Pedestrian Volume) | 0.10 | 1.11 | 0.862 | 0.982 | 1.113 |
| Speed (km/h) | 0.00 | 1.00 | 0.994 | 1.000 | 1.005 |
| Pedestrian/Vehicle Volume Ratio | 0.00 | 1.00 | 0.951 | 0.991 | 1.032 |
| Vehicle Age/Technology (%) | 0.15 | 1.16 | 0.634 | 0.918 | 1.364 |
| Road Use (%) | 0.05 | 1.05 | 0.806 | 1.009 | 1.278 |
| Design Configuration (%) | 0.13 | 1.14 | 0.603 | 0.841 | 1.150 |
| Ad hoc implementation of countermeasures (%) | −0.46 | 0.63 | 0.767 | 1.231 | 1.957 |
| Footpath Encroachment (%) | 0.00 | 1.00 | 0.785 | 0.900 | 1.026 |
| Age < 18 (%) | 0.06 | 1.06 | 0.921 | 1.316 | 1.867 |
| Age 18–49 (%) | 0.14 | 1.15 | 0.798 | 1.100 | 1.478 |
| Age 50+ (%) | −0.08 | 0.92 | 0.594 | 1.150 | 2.178 |
| Male Pedestrians (%) | 0.11 | 1.12 | 0.708 | 0.960 | 1.297 |
| Female Pedestrians (%) | −0.15 | 0.86 | 0.521 | 0.833 | 1.383 |
| Employed Population (%) | 0.20 | 1.22 | 0.832 | 1.318 | 2.187 |
| Maintenance Practices (%) | −0.10 | 0.90 | 0.702 | 1.097 | 1.714 |
| Pedestrian Infrastructure Coverage (%) | 0.07 | 1.07 | 0.407 | 0.632 | 0.973 |
| Street Furniture Vandalism | −0.03 | 0.97 | 0.901 | 0.998 | 1.109 |
| Age of Countermeasure (years) | −0.01 | 0.99 | 0.994 | 1.010 | 1.027 |
| Appropriate Countermeasure Location (1/0) | 0.04 | 1.04 | 0.891 | 0.980 | 1.079 |
| Scenario (Sample Size n and Noise Level) | Kendall’s τ | p-Value |
|---|---|---|
| n = 1000, noise = 1.0 | 0.611 | 0.000 |
| n = 1000, noise = 0.05 | 0.632 | 0.000 |
| n = 1000, noise = 0.10 | 0.695 | 0.000 |
| n = 2000, noise = 1.0 | 0.358 | 0.028 |
| n = 2000, noise = 0.05 | 0.337 | 0.040 |
| n = 2000, noise = 0.10 | 0.211 | 0.209 |
| n = 5000, noise = 1.0 | 0.442 | 0.006 |
| n = 5000, noise = 0.05 | 0.516 | 0.001 |
| n = 5000, noise = 0.10 | 0.558 | 0.000 |
| Variable/Factor | Coefficient (β) | Risk Factor (Fi) = eβ | In NB Model | iRAP Covered | Practical Notes |
|---|---|---|---|---|---|
| Log (Avg Daily Traffic Volume) | −0.150 | 0.86 | included | included | iRAP uses traffic flow |
| Log (Avg Daily Pedestrian Volume) | 0.10 | 1.11 | included | included | Pedestrian exposure proxy |
| Speed (km/h) | 0.00 | 1.00 | included | included | iRAP core attribute |
| Pedestrian/Vehicle Volume Ratio | 0.00 | 1.00 | included | excluded | Traffic exposure factor |
| Vehicle Age/Technology (%) | 0.15 | 1.16 | included | excluded | The age of the vehicle fleet is crucial in DCs |
| Overtaking Tendency | N/A | N/A | excluded | excluded | Critical in DCs |
| Traffic Rule Enforcement | N/A | N/A | excluded | excluded | Institutional variable |
| Public Safety Awareness (%) | N/A | N/A | excluded | excluded | Critical in DCs |
| Driver Safety Awareness (%) | N/A | N/A | excluded | excluded | Critical in DCs |
| Time of Day Visibility | N/A | N/A | excluded | included | Lighting is a proxy |
| Road Use (%) | 0.05 | 1.05 | included | included | Functional classification included |
| Design Configuration (%) | 0.13 | 1.14 | included | included | Includes medians, crossings, etc. |
| Ad hoc implementation of countermeasures (%) | −0.46 | 0.63 | included | excluded | Planning sequence not captured |
| Footpath Encroachment (%) | 0.00 | 1.00 | included | excluded | Informal sector factor |
| Human Capacity of Agencies | N/A | N/A | excluded | excluded | Institutional capacity—not modelled |
| Age < 18 (%) | 0.06 | 1.06 | included | included | covered under the Star rating for schools |
| Age 18–49 (%) | 0.14 | 1.15 | included | excluded | High-activity demographic |
| Age 50+ (%) | −0.08 | 0.92 | included | excluded | Vulnerable group not addressed |
| Male Pedestrians (%) | 0.11 | 1.12 | included | excluded | Demographic dimension |
| Female Pedestrians (%) | −0.15 | 0.86 | included | excluded | Gender exposure gap |
| Employed Population (%) | 0.20 | 1.22 | included | excluded | Mobility-related risk |
| Maintenance Practices (%) | −0.10 | 0.90 | included | included | Maintenance quality implied in iRAP |
| Pedestrian Infrastructure Coverage (%) | 0.07 | 1.07 | included | included | iRAP footpath attribute |
| Street Furniture Vandalism | −0.03 | 0.97 | included | excluded | Social disorder indicator |
| Age of Countermeasure (years) | −0.01 | 0.99 | included | excluded | Asset age is important in DCs |
| Appropriate Countermeasure Location (1/0) | 0.04 | 1.04 | included | included | Part of iRAP’s star logic |
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Mubiru, J.; Evdorides, H. Quantifying the Risk Impact of Contextual Factors on Pedestrian Crash Outcomes in Data-Scarce Developing Country Settings. Future Transp. 2025, 5, 151. https://doi.org/10.3390/futuretransp5040151
Mubiru J, Evdorides H. Quantifying the Risk Impact of Contextual Factors on Pedestrian Crash Outcomes in Data-Scarce Developing Country Settings. Future Transportation. 2025; 5(4):151. https://doi.org/10.3390/futuretransp5040151
Chicago/Turabian StyleMubiru, Joel, and Harry Evdorides. 2025. "Quantifying the Risk Impact of Contextual Factors on Pedestrian Crash Outcomes in Data-Scarce Developing Country Settings" Future Transportation 5, no. 4: 151. https://doi.org/10.3390/futuretransp5040151
APA StyleMubiru, J., & Evdorides, H. (2025). Quantifying the Risk Impact of Contextual Factors on Pedestrian Crash Outcomes in Data-Scarce Developing Country Settings. Future Transportation, 5(4), 151. https://doi.org/10.3390/futuretransp5040151

