Expanding the Brussels ring road and the myth of travel time savings

ABSTRACT

In April 2021, the Flemish government published their plans for the redevelopment of the R0, the larger ring road around Brussels. These plans include a social cost-benefit analysis (SCBA) and an environmental impact assessment report (EIA) in which the pros and cons of various plan alternatives are weighed against each other. The current paper is a critical analysis of both official documents, and assesses to what extent recent academic insights regarding induced travel are being dealt with in the planning process for this motorway redevelopment project. Drawing upon a literature review, it is concluded that the existing body of knowledge on induced travel is largely ignored by the planning documents scrutinised, which suggests that the SCBA overestimates the economic benefits of the project, while the EIA underestimates the environmental impacts. While a road pricing scheme would potentially support the achievement of the stated planning objectives, it is not included in any of the proposed plan alternatives.

KEYWORDS:

• Travel time savings
• road capacity
• induced travel
• social cost benefit analysis
• Brussels

1. Introduction

The R0, better known as the larger ring road around Brussels, is the second busiest and therefore one of the most congestion-prone motorways in Belgium. The very visible congestion problem, as well as a number of road safety issues, have caused the Flemish government to consider the possible redesign and expansion of the northern segment of the R0 stretching between the Groot-Bijgaarden and Sint-Stevens-Woluwe junctions since 2003 (Figure 1).

Figure 1. The northern segment of the R0 stretching from Groot-Bijgaarden to Sint-Stevens-Woluwe (map data from OpenStreetMap).

The planning process for the R0 is a distinctly political decision-making process, given the diversity of stakeholders and the stratification of interests that are defined by particular value and norm patterns among stakeholders (Martens & van Weelden, 2014). To cite just a few examples: residents living near the ring road are primarily troubled by the threats of noise pollution and potential damage to the landscape, businesses located near a motorway junction prioritise smooth traffic flows, and residents of Brussels find it important that no more polluting cars will be attracted into the city. But beyond such idiosyncratic priorities, more abstract interests are at stake too, which often are ideological in nature. Adding extra road capacity will support the growth of road traffic, which may represent economic growth. But at the same time, such growth will entail more greenhouse gas and air pollutant emissions, rising economic dependence on road transport, and accelerating processes of suburbanisation. Moreover, widening the road is not a solution to congestion (Duranton & Turner, 2011), nor is building road infrastructure an intervention that can be repeated over and over again in the future, as at some point the space to accommodate even more traffic on the road will be used up. Moreover, the fact that quite a few policymakers consider congestion to be at the core of the mobility problem (Taylor, 2004) is a discourse fuelled by the frustration of only part of the road users, and not, for instance, by those groups that are only slightly dependent on cars and thus have little interest in investing in motorways (Litman & Brenman, 2012).

Despite the unambiguously political nature of decision-making (Keblowski & Bassens, 2018), the planning process for the R0 is dominated by a series of technical studies, including environmental impact assessments (EIA) and cost-benefit analyses (CBA). These analyses largely follow standardised research methods to quantify the environmental and economic impacts of different scenarios. The technicality of these expert-written reports, which quantify the expected impacts in as much detail as possible, fuels the idea that a transport infrastructure planning process is some sort of scientific research, the results of which can objectively indicate which plan alternative is best. In particular, the tool of CBA pretends that all effects, including travel time gained, healthy life years, and human lives, can be monetised, and that it is possible to consider the cumulative effect as a joint benefit (or cost) to society (Brent, 2017).

Richardson (2005) described this problem using a number of case studies. On this basis, he notes that the rationale behind technical studies equally reflects social power relations, and that the choices made in the analysis are driven by interests and value frameworks of clients and experts involved. Also more recently, quite a few authors have expressed criticism towards the presumed validity of employing CBA outcomes as a basis for planning decisions (see e.g. Beukers et al., 2012; Hickman, 2019; Mouter et al., 2015; Nicolaisen and Naess, 2014; 2015; Van Wee, 2012). Unsurprisingly, estimating the value of a human life lost in a crash (Banzhaf, 2014; Kip Viscusi & Aldy, 2003), or of a healthy year of life lost due to air pollution (Hubbell, 2006) are known as controversial issues.¹ What is less known is that there is also a debate on how travel time savings are taken into account in CBAs. Simply explained, travel time savings is the assumed economic benefit of traffic that is supposedly flowing more smoothly after the road has been widened.

The controversy over the value estimation of travel time savings relates to the concept of induced travel. Indeed, observations show that in a dynamic regional-economic system, building additional road capacity eventually leads to the creation of additional traffic, which in the long run does not necessarily eliminate congestion, neither reduces travel times. In other words, wider roads often do not lead to shorter, but rather to wider traffic jams (Boussauw, 2014). At the time of writing, it is not common practice to take induced travel into account in EIAs, and the methodological recommendations for the preparation of CBAs of the European Union (EU – DG Regio) (Sartori et al., 2014) do not mention anything about it either. Nevertheless, the recent transport economics literature takes the phenomenon very seriously.

The aim of the current paper is to perform a critical analysis of the selective manner in which recent academic insights regarding induced travel are dealt with in the particular case study of the redevelopment of the R0. Additionally, the possible impact of fully accounting for induced travel on the conclusions of the planning documents for the R0 will be elaborated on. Although such a case-study approach certainly has its limitations, it can nourish a more critical approach to the concept of travel time savings in wider practices of transport planning, and conclusions may apply to similar projects elsewhere. Note that the notion of similarity pertains mostly to levels of road capacity saturation and public transport offer, which may differ substantially from the R0 case.

2. The planning process for the redevelopment of the R0

Although the first studies on modernising the R0 date back to 2003, it was not until 2011 that the planning process gained momentum with the preparation of a strategic environmental impact assessment report (S-EIA) that examined various options. Most scenarios consisted of a combination of optimisation and expansion of the existing infrastructure with ‘fiscal measures’ (which usually meant some form of road pricing) and with public transport and cycling infrastructure improvements. One rather unconventional scenario was developed in which the western and eastern branches of the E40 motorway would be connected by means of a 14 kilometre long continuous tunnel under the Brussels Capital Region. The option of including some form of road pricing in all scenarios was supported by a 2012 study by the consultant Transport & Mobility Leuven (Delhaye et al., 2012, commissioned by the Flemish green party) which showed that infrastructure modifications would in no case be sufficient to control congestion. In 2013, the Flemish government announced the results of the SCBA that had studied the scenarios of the EIA, and on that basis the Flemish government opted for the so-called ‘Scenario 1’, in which the construction of a parallel structure along the existing R0 would be combined with investments in public transport and bicycle connections, and with fiscal measures. However, the SCBA does not comment on the nature of those fiscal measures. Although at the time the introduction of road pricing seemed a realistic option for the Flemish government, and in particular for the then Flemish minister of mobility and public works Ben Weyts (member of the Flemish nationalist party), the latter changed his stance in April 2019, allegedly due to lack of public support for such measures (VRT NWS, 2019). Since then, the studies for the R0 have no longer included road pricing as an option.

It is notable that the planning proposals for the R0 have evolved significantly over the years. In 2008, it was still a pure road infrastructure project, with the objective of optimising the motorway in terms of traffic flow and road safety, to be achieved by building parallel roads and increasing road capacity based on a uniform scheme of four through plus three parallel lanes per direction. With the drafting of the EIA, the focus was broadened, and a vision was developed of an overall programme for multimodal accessibility, which would also include major investments in public transport and cycling infrastructure. A vision memorandum on the ring road works programme (Werkvennootschap, 2019) emphasises combating through traffic, reducing the number of crashes, building a so-called bicycle express network, constructing a number of high-quality light-rail and bus links (the Brabant public transport network), and developing a range of park-and-ride locations. The vision memorandum, which has no legal status, does not mention increasing road capacity or widening the motorway. That said, the project as proposed in the formal planning documents does include road capacity expansion, albeit less drastically than the widening that was envisaged in 2008.

Before moving to the analysis, it is important to provide an overview of the legally required procedures. In the EU, EIA at plan level is regulated by Directive 2001/42/EC, which mandates that any plan that is likely to cause significant environmental impact must be subject to an EIA. The member states of the EU have implemented this directive in national or regional legislation. In federal Belgium, environmental policy is a competence of the regions. The plan for the R0 is located almost entirely on the territory of the Flanders region, which means that legislation of the Flanders region applies. In Flanders, this EU directive was implemented in the ‘decree concerning the environmental impact assessment of plans and programmes’ of 12 October 2007. In Flanders, since 1 May 2017, any EIA that concerns a plan needs to be integrated into the procedure for drawing up or amending regional zoning plans (which are also called ‘spatial implementation plans’, after ‘ruimtelijke uitvoeringsplannen’ in Dutch). This procedure includes two mandatory public review stages, during which the plan is made available for consultation to both the public and all competent authorities. In the planning process for the R0, more public review stages are provided than just the legally required ones. The first public review stage ran from 1 June 2018 to 30 July 2018. The scoping note that is critically discussed in the current paper was the subject of a second round of public review, which ran from 25 May 2021 to 23 July 2021. In the process, the concerned municipalities and the Brussels Capital Region can participate, but they are not responsible for drawing up the EIA report or the spatial implementation plan, since these fall entirely under the competence of the Flanders region.

With regard to performing CBAs, in Flanders, no national or regional legislation applies for road construction projects. However, EU Regulation 1303/2013 applies, which stipulates that a CBA must be submitted for ‘large projects’ for which support is requested from the European Regional Development Fund (ERDF). A project is considered large if the value of the part of the budget that is eligible for subsidy exceeds 50 million euros. If applicable, such a CBA should be performed according to the ‘Guide to Cost-Benefit Analysis of Investment Projects: Economic appraisal tool for Cohesion Policy 2014–2020’ (Sartori et al., 2014). The co-financing by ERDF of some of the construction projects related to the R0 largely explains the methodology used in drawing up the SCBA. It means that our critical analysis of how this particular SCBA was performed pertains not only to the R0 project, but also to the EU’s CBA guide (Sartori et al., 2014).

From a technical point of view, it is important to note that both EIA and SCBA largely rely on a regional traffic model that is developed and maintained by the Flemish Traffic Centre, a public regional government agency, in collaboration with their consultants. The backbone of the model consists of survey-based origin-destination matrices that are calibrated on the basis of traffic counts. A detailed explanation of how the traffic on the R0 and its surroundings is generated and distributed across the transport infrastructure networks is beyond the scope of the current paper.

3. ‘Scoping note 2’ dissected

In what follows, the document ‘Scoping Note 2’ will be examined. It was published by De Werkvennootschap (which is the public company that is in charge of the larger ring road works programme) on 2 April 2021, and forms the basis for the regional zoning plan for the ‘Spatial redevelopment of the Brussels Ring Road (R0) - part North’ (Werkvennootschap, 2021a). The Scoping Note coordinates a series of sub-studies, including ‘Results of Social Cost-Benefit Analysis – Loop 1’ (SCBA) (Werkvennootschap, 2021b) and ‘Results of Environmental Impact Assessment Loop 1’ (EIA) (Werkvennootschap, 2021c).

In what follows, four dimensions will be investigated:

1. The principle of considering travel time savings as a social benefit by the SCBA;

2. The way in which the monetary value of regional-economic social benefits is estimated by the SCBA;

3. The way in which the EIA estimates the magnitude of future environmental impacts;

4. The absence of a plan alternative that includes road pricing in the SCBA.

The Scoping Note examines three plan alternatives (called G1, G2 and G3), with each plan alternative comprising several variants. Plan alternative G1 mainly involves restructuring a number of junction complexes, where additional lanes would be built between the junctions of Groot-Bijgaarden and Strombeek-Bever, and at Zaventem, but no new parallel roads. Plan alternative G2 does provide for new parallel roads, notably between Groot-Bijgaarden and Strombeek-Bever, and between Machelen and Sint-Stevens-Woluwe. In plan alternative G3, parallel roads are provided but partly use existing local road infrastructure. In each plan alternative, additional lanes are constructed, and in plan alternative G2 this is done in the most structural way. It is important to note that the Scoping Note does not provide detailed information on how much road capacity exactly is added in each plan alternative, either in absolute terms (number of additional kilometres of lane) or in relative terms (percentage). In what follows, only the variants that, according to the analyses in the Scoping Note, overall appear to be the most promising ones, namely G1A2 and G2A1, will be referred to.

3.1 Travel time savings as a social benefit (SCBA)

According to the SCBA, the monetised travel time savings related to ‘person’s mobility’ and ‘goods mobility’ together represent 69% of the total estimated benefits, both in plan alternative G1A2, and in plan alternative G2A1 (Tables 72 and 73, p. 211–212). It means that travel time savings are the main economic argument for redesigning the northern R0. It also means that it is crucial to understand and justify why travel time savings can or should be considered a social benefit. The methodology used in preparing the SCBA largely follows the EU (DG Regio) recommendations for CBA (Sartori et al., 2014). The monetisation of travel time savings, meaning that travel time savings are estimated and then multiplied by an amount of money per hour saved, has been common practice in pre-assessing planned transport infrastructure projects since the 1960s. In CBAs, travel time savings typically account for some 80% of monetised benefits (Metz, 2008a). DG Regio (Sartori et al., 2014) has uncritically adopted this approach in its recommendations, ignoring the critical literature that has developed around this topic over the last 15 years.

Naess (2006) believes that the method is based on a theoretical economic model that is far from reality. Metz (2008a) argues that at the macro level, no travel time savings are usually observed after road capacity expansion, as quasi all statistics that document the issue at stake show that in regions where road infrastructure is added, the amount of time people spend on travel either remains constant, either increases, but certainly does not decrease. Incidentally, this is also the case at project level, albeit only in the slightly longer term (order of magnitude of 10 years). The philosophy that is adopted in the SCBA sees traffic growth as an autonomous process, driven by economic growth, which causes congestion that in turn must be remedied by building additional road capacity. However, Duranton and Turner (2011) have shown that building additional road capacity enables traffic growth, and thus in fact co-causes this growth. Garcia-López et al. (2020) recently confirmed this phenomenon for European urban areas. Naess et al. (2012) pointed out that CBAs usually do not take induced travel into account, and thus not only overestimate benefits of travel time savings, but also call into question the very concept of travel time savings. Incidentally, the problem of ignoring induced travel also arises in the EIA, about which more will be explained in section 3.3 of this paper. But even if the adopted SCBA philosophy is followed, there is no evidence that building additional road capacity will result in real travel time savings over time. A very recent case study of a section of the London urban-regional ring road (M25) supports this view (Metz, 2021).

While transport economists agree that creating additional road capacity in a saturated infrastructure network can generate economic benefits (Banister & Berechman, 2001), there is no consensus that travel time savings can serve as an accurate basis for estimating such economic benefits. Metz (2008b) summarises the various pros and cons of using travel time savings as an indicator of the possible realised economic benefit and concludes that these should instead be expressed as an improvement of accessibility. In this context, ‘improved accessibility’ specifically means that more people are in a position to visit certain destinations that were previously not within their reach. In the R0 SCBA, however, these kinds of accessibility benefits are covered by Chapter 6 that deals with ‘indirect effects’ (translation), which will further be referred to as ‘regional-economic effects’ in section 3.2 of the current paper. If the logic of Metz (2008a) would be followed, this involves double counting: monetising travel time savings is only justifiable if such estimated savings would be viewed as a (very imprecise) proxy for the expected regional-economic benefits. The double-counting hypothesis is supported by the following explanation from the SCBA (in translation): ‘The main inputs to ISEEM² are the changes in time costs and volumes predicted by the transport network model’. (SCBA, p. 90).

The expected regional-economic benefits as estimated by the SCBA are much lower than the benefits of travel time savings, equivalent to roughly one-third of it (34% of the budgeted value of travel time savings in plan alternative G1A2, and 30% in plan alternative G2A1). This relatively modest size of the expected regional-economic benefits is in line with Banister and Berechman’s (2001) contention that in a dynamic regional-economic system that is already well provided with transport infrastructure, building additional capacity will hardly result in economic growth anymore.

3.2 Regional-economic impacts as a social benefit (SCBA)

The regional-economic impacts (referred to as ‘indirect effects’ in the SCBA), estimated using the ISEEM model, amount to 24% of the total benefits in plan alternative G1A2, and 21% in plan alternative G2A1, according to the SCBA. If the double-counting hypothesis that was proposed in the previous section of the current paper would be followed and if, on that basis, no travel time savings would be expected at all (i.e. travel time savings would be set equal to zero), then the regional-economic impacts would amount to 76% (plan alternative G1A2) and 68% (plan alternative G2A1) of the total benefits, respectively. Incidentally, in that case and ceteris paribus, the positive balance of plan alternative G1A2 would be only EUR 405 million (instead of EUR 2,374 million, as calculated by the SCBA), and in the case of plan alternative G2A1 only EUR 85 million (instead of EUR 2,349 million). Perhaps this is a too pessimistic view, as there may still be temporary travel time savings in the first years after construction that will have been compensated by induced travel only over time (order of magnitude of 10 years).

Regarding the calculation of the regional-economic impacts themselves, the following reservations can be made. The ISEEM model is a ‘black box’ as the SCBA only very superficially explains the way in which the results are obtained. According to Banister and Berechman (2001), the relationship between mobility and economic growth is not linear, but asymptotic, i.e. follows a flattening curve. This means that in an economically dynamic region, such as the Brussels metropolitan area, where a very extensive network of transport infrastructure is already available, more road capacity does not necessarily continue to lead to economic growth (unlike in economically less developed regions). It is not clear whether ISEEM’s forecasts take such an asymptotic relationship into account. This is important because a forecast based on a linear extrapolation of past observed effects might lead to an overestimation of regional-economic benefits.

3.3 Estimation of future environmental impacts (EIA)

The estimation of future environmental impacts is based on projections provided by the PLANET model of the federal economic planning agency of Belgium (Bureau fédéral du Plan/Federaal Planbureau). However, PLANET is a macroeconomic model, which does not take into account induced travel, being the additional traffic that will be created by the expansion of road infrastructure itself. Indeed, both theoretical considerations (Duranton & Turner, 2011) and empirical research (Hymel, 2019; Litman & Colman, 2001) indicate that, in an economically dynamic region (such as the Brussels metropolitan region), adding road capacity to routes that experience heavy traffic loads leads to road infrastructure saturation again in the long run (order of magnitude: 10 years). This effect should not only be expected on the R0, but at least partly on the nearby local road network as well.

Neither the Scoping Note, the SCBA nor the EIA take into account the phenomenon of induced travel that is at the root of any objections that could be raised to the use of the concept of travel time savings. On p. 478 and on p. 2250 of the EIA, it is very briefly mentioned that (translation) ‘… plan alternatives and variants with higher capacity (…) overall (result) in a slightly higher traffic volume (counted as vehicle kilometres) in the region. This may be the effect of undesirable evolutions (additional trips)’. However, the tiny traffic volume fluctuations referred to by the EIA are not in line with the literature, and macroscopic effects of induced travel are clearly not calculated by the regional traffic model. The SCBA (p. 90) very briefly refers to induced travel as (translated) ‘latent demand’, clarifying that this effect is not calculated by the traffic models, but that this latent demand, associated with new jobs expected by ISEEM, (translated) ‘may be quite small’. However, nothing is said about latent demand or induced travel not related to the estimated number of new jobs, but to changing destination and location choice behaviour. Nor is anything said about the fact that the EIA does not include the environmental impact (and congestion) caused by these additional trips in its calculations. However, estimating the impact of induced travel is not trivial, but rather crucial when pre-assessing transport infrastructure projects in an economically dynamic region (J. M. B. Volker et al., 2020). To this end, the National Center for Sustainable Transportation (University of California, Davis) developed an ‘Induced Travel Calculator’ for California (Volker and Handy, 2020). Based on data from the literature, this simulation tool uses an elasticity of 1.0 for ‘interstate highways’ (similar to the Belgian motorways), and 0.75 for roads in a lower category, in the long term (10 years). An elasticity of 1.0 means that if highway capacity is increased by, say, 20%, after 10 years, a 20% increase in daily traffic volume is expected (or 15% additional traffic volume on lower ranked roads for which an elasticity of 0.75 is assumed).

This means that estimating the environmental impact is preferably done on the basis of a saturation level that is comparable to the current saturation level, and thus not on the basis of PLANET forecasts. The Flemish regional traffic model is not suited for this purpose either, as this model is not capable of capturing and modelling the phenomenon of induced travel in all its complexity (including changing location choices by households and employers, as well as accelerated suburbanisation processes) (Ronse et al., 2015). On this basis, it could be argued that the long-term (10-year) environmental impacts, especially in terms of air quality, are systematically underestimated by the EIA. The actual percentage increase in road capacity on the northern R0, which could serve as a basis for a realistic assessment of environmental impacts, cannot be directly deduced from the Scoping Note.

3.4 Absence of a plan alternative with road pricing (SCBA and EIA)

There has long been consensus in the transport economics literature that the cost-benefit ratio can be optimised by introducing dynamic road pricing (Button & Verhoef, 1998). The economic theory behind it states that road pricing can be used to economically optimise the use of transport infrastructure, to minimise the demand for additional road capacity and to make the infrastructure quasi-congestion-free. Nowadays, several practical examples, with Stockholm (Börjesson et al., 2012) being the best case comparable to the Brussels metropolitan region, show that this model works.

An economic evaluation of the redevelopment of the R0 is incomplete without a scenario that includes road pricing. This is particularly important when insisting on monetising travel time savings. Unlike road capacity expansion, it can be demonstrated that dynamic road pricing can lead to real travel time savings in the long term and at the macro level, since the price level can be ‘tuned’ to avoid congestion and make travel time predictions reliable.

Eliasson (2009) published a CBA of the implementation of the smart road pricing system in Stockholm, in which, among other things, travel time savings were monetised. Unlike most CBAs, which like the one for the northern R0 are model-based pre-assessments, Eliasson’s CBA was made after implementation of the road pricing system. Therefore, the data used were observed, and thus not modelled. This also means that the monetised travel time savings are real, because they are measured. Unlike road infrastructure reconfiguration and capacity expansion, the literature indicates that road pricing does involve a direct and permanent reduction of traffic volumes, with consequent positive effects on traffic flows. In the case of Stockholm, the estimated value of travel time savings is around 70% of the kilometre charge as paid by motorists. On top of the actual travel time savings, significant benefits arose from more reliable, predictable travel times, as well as important environmental benefits. Overall, the social benefits outweigh the social costs by far.

4. Conclusion

The results of the technical analyses of both the SCBA and the EIA that make up ‘Scoping Note 2’ are valid only within the framework of the assumptions taken by the respective experts. To any reader of these studies that has no additional knowledge of the current academic debates on transport planning, it appears that the standards used are objective and value-free, and thus cannot be subject to debate. However, recent academic insights indicate that not taking induced travel into account is a major flaw. If the studies would have taken induced travel into account, the results would have looked quite differently.

I would like to summarise the conclusions of this paper as follows:

1. The standards adopted by the technical analyses, including the SCBA and the EIA, are determined by values, norms and knowledge of those who developed these standards. In particular, the EU’s (DG Regio) methodological recommendations for the elaboration of CBAs (Sartori et al., 2014) are not sufficiently up-to-date with regard to the inclusion of induced travel.

2. The main benefit category that was estimated by the SCBA is based on the unproven and perhaps fictitious assumption that the redevelopment of the R0 without dynamic road pricing will lead to real travel time savings even in the long run.

3. The regional-economic benefits of the redevelopment as estimated by the SCBA are possibly overestimated as the effect of adding transport infrastructure on economic growth is asymptotic.

4. Longer-term environmental and health impacts are underestimated by the EIA, as these impacts were calculated based on a model that does not account for traffic induced by the redevelopment of the R0.

5. If reducing congestion and saving travel time on the R0 are real planning goals, then introducing some form of dynamic road pricing is necessary.

Obviously, a reorganisation of the R0 aimed at disentangling through traffic from local traffic is useful as it may support both road safety and driver comfort. However, it is less clear why this should be accompanied by an increase of road capacity. A plan alternative that would seek to facilitate exactly the same volume of road traffic as in the reference situation, controlled by dynamic road pricing, and combined with a drastically reduced speed regime, is absent from the Flemish government’s current proposal. However, such a plan alternative would do a much better job in terms of improving traffic flows, supporting road safety, and attaining environmental objectives.

Since the scope of an individual case study is inherently limited, it is important to question the extent to which the findings can be generalised. It is clear that induced travel should only be anticipated in economically dynamic regions with a prevalence of structural congestion on major motorway connections. What is less clear is the possible mediating role of public transport in this. Quite a few studies have assessed induced travel mostly in a North American context (e.g. Duranton & Turner, 2011), where rail usually does not offer a viable alternative to car travel. However, in numerous European metropolitan areas, such as Brussels, it could be argued that rail is a viable alternative for many. Garcia-López et al. (2020) confirm that improving the provision of public transport can have a mitigating effect on congestion in urbanised areas. While further research is needed to understand the impact of the local context, our analysis still suggests that the way travel time savings are monetised in CBAs needs to be reconsidered, and pertains not only to the R0 case, but also to the EU’s CBA guide (Sartori et al., 2014).

Acknowledgments

I would like to thank Dr. Eng. Koos Fransen for his critical feedback.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

1. In the SCBA for the R0, the value of a human life is equated to €3,575,721 (approximately €3.6 million), in 2016 prices.

2. ISEEM is the model that measures regional-economic impacts.