VeSTEM
Source: Commission modelling inventory and knowledge management system (MIDAS)
Date of Report Generation: Mon Apr 22 2024
Dissemination: Public
© European Union, 2024
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Overview
Acronym
VeSTEM
Full title
Vehicle Safety Technology Effectiveness Model
Main purpose
The VeSTEM model allows predicting casualty savings and costs arising from the simultaneous implementation of multiple vehicle safety systems and their interactions in preventing and mitigating of collisions. Model outputs allow evaluating the cost-effectiveness and casualty prevention potential of different sets of systems for the assessment of policy impacts.
Summary
VeSTEM has been developed by TRL within the context of the revision of the General Safety Regulation and Pedestrian Safety Regulation. The model determines the cost-effectiveness of different sets of safety measures to be implemented on a mandatory basis. The combined effect of a set of safety systems may be smaller than the sum of individually predicted effects because the target populations for different systems are partially overlapping but each casualty can only be prevented once. The model allows to arrange systems into a layer structure to avoid such overestimation of benefits.
The modelled benefits (monetary values of casualties prevented or mitigated by safety measures) and costs (cost to vehicle manufacturers of fitment of safety measures to new vehicles) are compared with a baseline scenario, where none of the policy options are implemented on a mandatory basis, but voluntary uptake of safety measures continues.
Six vehicle categories (M1, M2, M3, N1, N2 and N3) are considered across a geographical scope of the entire European Union (27 Member States) and UK. The evaluation period covers 16 years to allow for a full cycle of fleet benefits to be captured.
Model categories
Transport
Model keywords
Transportcosts and benefitssafety measuresroad collisions
Model homepage
Ownership and Licence
Ownership
Third-party ownership (commercial companies, Member States, other organisations, …)
Ownership details
Licence type
Non-Free Software licence
The license has one or more of the following restrictions: it prohibits creation of derivative works; it prohibits commercial use; it obliges to share the licensed or derivative works on the same conditions.
Details
Structure and approach
VeSTEM is a model to estimate the benefits (monetary values of casualties prevented by safety measures) and costs (cost to vehicle manufacturers of fitment of safety measures to new vehicles) associated with policy measures assessed in the context of the revision of the General Safety Regulation and Pedestrian Safety Regulation. The model is implemented in the programming language Python (https://www.python.org/) with inputs and outputs produced in Microsoft Excel spreadsheets.
The model considers as benefits the monetary values of casualties prevented by safety measures, and as costs the cost to vehicle manufacturers of fitment of safety measures to new vehicles. Results are benefit-to-cost ratios (BCRs), based on present monetary values and casualties prevented, compared to the baseline scenario over the entire evaluation period.
A vehicle fleet calculation module determines how the vehicle safety measures disperse into the fleet. The module determines the effect of mandating a measure for all new types, and two years later for all new registered vehicles, on the overall proportion of the fleet equipped. Benefits conferred by a safety measure, that is, casualties prevented, will only be realised by equipped vehicles. However, the legacy fleet will also be affected by active safety measures; for example, if a rear-end shunt is avoided by advanced emergency braking for driving and still-standing vehicles ahead, the vehicle in front, will benefit from the measure even if it is a legacy vehicle. This is taken into account in the benefit calculations.
To simulate the casualties prevented by each measure, an accident data analysis was performed based on Great Britain national road accident data (Stats19) to determine the casualty target population for each proposed measure (input data), i.e. the number of fatal, serious and slight injuries that could potentially be affected by a safety measure based on relevant characteristics of the collision (e.g., collision geometry or contributory factors). The target populations were scaled to EU-27 and UK level using weighting factors, based on severity and vehicle categories involved, derived from analysis of the pan-European CARE database. The target populations found are multiplied with effectiveness values for each safety measure (input data), i.e. a percentage value indicating what proportion of the relevant accidents will be avoided or mitigated by the measure. Mitigated casualties (fatal turned to serious casualty, or serious to slight casualty) are added to the target population of the next lower injury severity level for other measures. The casualties prevented are multiplied with monetary values for casualty prevention to calculate the monetary benefit.
The model also addresses the interaction of different safety measures on overlapping casualty groups. To give an example, there are collisions where a driver was exceeding the speed limit, left the lane and suffered a frontal impact. These collisions will be in the target populations for multiple measures, but they can only be prevented once by either one of these systems. This is addressed in the model by removing casualties prevented by one measure from the subsequent target population of the other measures. The impact of highly effective existing safety measures, which have been mandatory for a few years, but are still dispersing into the vehicle fleet is also modelled to reduce the remaining target populations for the proposed measures.
The cost of a policy option is calculated by multiplying per-vehicle cost estimates (input data) for each measure with the number of new vehicles of each vehicle category across EU-27 and UK that are equipped with the measure in the given year of the analysis according to the output of the fleet calculation model. In the economic calculation module, the monetary values of costs and benefits are subjected to inflation and discounting to determine their present value. The present values of benefits and costs exceeding the baseline, calculated for individual years and summed over the study period, are compared in order to arrive at cost-effectiveness estimates.
Input and parametrization
Benefits considered:
- monetary values of casualties prevented by safety measures
Costs considered:
- cost to vehicle manufacturers of fitment of safety measures to new vehicles
Main output
Results:
- Number of fatal, serious and slight casualties prevented
- Benefit-to-cost ratios (BCRs), based on present monetary values and casualties prevented, compared to the baseline scenario over the entire evaluation period.
Spatial & Temporal extent
The output has the following spatial-temporal resolution and extent:
| Parameter | Description |
|---|---|
| Spatial extent / country coverage | EU Member states 27 and UK |
| Spatial resolution | World-regions (supranational)Entity |
| Temporal extent | Medium-term (5 to 15 years) |
| 2021-2037 | |
| Temporal resolution | Years |
Quality & Transparency
Quality
Model uncertainties
Models are by definition affected by uncertainties (in input data, input parameters, scenario definitions, etc.). Have the model uncertainties been quantified? Are uncertainties accounted for in your simulations?
- response
- yes
- details
- Input parameters having a relatively high associated uncertainty were identified and given upper and lower bounds of variation. These were used to calculate variation in the BCR (from absolute lower BCR to absolute upper BCR).
- url
Sensitivity analysis
Sensitivity analysis helps identifying the uncertain inputs mostly responsible for the uncertainty in the model responses. Has the model undergone sensitivity analysis?
- response
- yes
- details
- Two sensitivity analysis techniques were used: An interval and a scenario analysis were carried out to quantify the range of uncertainty around the best estimate BCR values.
- url
Have model results been published in peer-reviewed articles?
- response
- no
- details
- url
Has the model formally undergone scientific review by a panel of international experts?
Please note that this does not refer to the cases when model results were validated by stakeholders.
- response
- no
- details
- url
Model validation
Has model validation been done? Have model predictions been confronted with observed data (ex-post)?
- response
- yes
- details
- The model has been verified during the course of implementation using dummy inputs and verifying the individual calculation steps data, but the model has not been validated ex-post.
- url
Transparency
To what extent do input data come from publicly available sources?
This may include sources accessible upon subscription and/or payment
- response
- Based on both publicly available and restricted-access sources
Is the full model database as such available to external users?
Whether or not it implies a specific procedure or a fee
- response
- no
- details
- Collision databases used to create input data for the model (STATS19 and CARE) can be accessed at request to the database owner. Other input data was collected from literature and stakeholders and is provided in the project report (see References).
- url
Have model results been presented in publicly available reports?
Note this excludes IA reports.
- response
- yes
- details
- documents
For details please refer to the 'peer review for model validation' documents in the bibliographic references
Have output datasets been made publicly available?
Note this could also imply a specific procedure or a fee.
- response
- no
- details
- Model results were made publicly available in the project report.
- url
Is there any user friendly interface presenting model results that is accessible to the public?
For instance: Dashboard, interactive interfaces...
- response
- no
- details
- url
Has the model been documented in a publicly available dedicated report or a manual?
Note this excludes IA reports.
- response
- yes
- details
- General model structure, input data and results are documented in a project report.
Is there a dedicated public website where information about the model is provided?
- response
- no
- details
- url
Is the model code open-source?
- response
- no
- details
Can the code be accessed upon request?
- response
- no
- details
The model’s policy relevance and intended role in the policy cycle
The model is designed to contribute to the following policy areas
- Transport
The model is designed to contribute to the following phases of the policy cycle
- Formulation – such as ex-ante Impact Assessments
The model’s potential
VeSTEM can be used to model the future dispersion of vehicle safety systems into the EU fleet and quantify the EU-wide number of casualties prevented by voluntary or mandatory implementation of the systems. The model also allows to monetise the casualty savings (benefits) and calculate fitment costs associated with the systems (cost) and perform cost-effectiveness calculations for policy options including different sets of safety measures.
Previous use of the model in ex-ante impact assessments of the European Commission
Use of the model in ex-ante impact assessments since July 2017.
2018SWD/2018/190 final
Impact assessment accompanying the document Proposal for a Regulation of the European Parliament and of the Council on: type-approval requirements for motor vehicles and their trailers, and systems, components and separate technical units intended for such vehicles, as regards their general safety and the protection of vehicle occupants and vulnerable road users, amending Regulation (EU) 2018/ … and repealing Regulations (EC) No 78/2009, (EC) No 79/2009 and (EC) No 661/2009
- Lead by
- GROW
- Run by
- TRL Limited
- Contribution role
- baseline and assessment of policy options
- Contribution details
The model helped to assess the following impacts:
- Governmental administrative burden
- Prices, quality, availability or choice of consumer goods and services
- Safety or sustainability of consumer goods and services
- Impact on vulnerable consumers
- Significant effects on sectors
- Health and safety of individuals/populations