For whom the bell tolls: Road safety effects of tolls on uncongested SCUT highways in Portugal

Alfredo Marvão Pereira, Rui Marvão Pereira, Joao Pereira dos Santos

Article ID: 1163
Vol 4, Issue 2, 2021, Article identifier:287–305

VIEWS - 59 (Abstract) 25 (PDF)


We present a difference-in-differences analysis of the road safety effects of introducing tolls on SCUT highways in Portugal, a policy motivated purely by financial considerations, as congestion was never an issue. Using negative binomial count models and a comprehensive dataset on all mainland municipalities covering 2008 to 2014, we find that introducing tolls led to an increase in the total numbers of accidents and road injuries in municipalities where SCUT highways are located. Additionally, we register a change in the composition thereof, with fewer occurrences on highways (including on SCUT highways) and an increase on national and other roads. Finally, we find that most effects pertained to light injuries. No statistically significant effects were identified for fatal or serious injuries. Furthermore, as a result of introducing tolls on SCUT highways, we estimate that around 20% of the toll revenue collected is lost on the costs linked to road accidents. This questions the rationale of introducing such tolls, even from a revenue-raising standpoint.


road safety; accident; injury; toll; difference-in-differences; SCUT; Portugal

Full Text:



Albalate D (2011). “Shifting death to their alternatives: The case of toll motorways”. Journal of Transport Economics and Policy, 45(3): 1–23.

Albalate D and Bel G (2012). “Motorways, tolls and road safety: Evidence from Europe”. SERIEs, 3: 457–473.

Angrist JD and Pischke J-S (2008). Mostly Harmless Econometrics: An Empiricist’s Companion. Princeton, NJ, USA: Princeton University Press.

Bertrand M, Duflo E and Mullainathan S (2004). “How much should we trust differences-in-differences estimates?” Quarterly Journal of Economics, 119(1): 249–275.

Bieckel P, Friedrich R, Burgess A, et al. (2006). “Proposal for harmonised guidelines”. HEATCO—Developing Harmonised European Approaches for Transport Costing and Project Assessment, Deliverable 5, Contract No. FP6-2002-SSP-1/502481. Brussels, Belgium: European Commission.

Currie J and Walker R (2011). “Traffic congestion and infant health: Evidence from E-ZPass”. American Economic Journal: Applied Economics, 3(1): 65–90.

Dias LL (2015). Pagamentos de Portagens nas Ex-SCUT—Qual o Impacto na Sinistralidade Rodoviária? [Toll Payments at Ex-SCUT—What is the Impact on Road Accidents?] Lisbon, Portugal: Faculdade de Ciências Socias e Humanas, Nova University Lisbon.

Donário AA and dos Santos RB (2011). The Economic and Social Costs of Road Accidents: The Case of Portugal. Lisbon, Portugal: EDIUAL—Autoridade Nacional de Segurança Rodoviária and Centro de Análise Económica de Regulação Social da Universidade Autónoma de Lisboa.

Green CP, Heywood JS and Navarro M (2014). “Did liberalising bar hours decrease traffic accidents?” Journal of Health Economics, 35: 189–198.

_____ (2016). “Traffic accidents and the London congestion charge”. Journal of Public Economics, 133: 11–22.

Guimarães P (2008). “The fixed effects negative binomial model revisited”. Economics Letters, 99(1): 63–66.

Haynes R, Jones A, Kennedy V, et al. (2007). “District variations in road curvature in England and Wales and their association with road-traffic crashes”. Environment and Planning A, 39(5): 1222–1237.

Instituto Nacional de Estatística (INE) (2008). Estatísticas de Transporte e Comunicação—2008 [Transport and Communication Statistics—2008]. Lisbon, Portugal: INE.

Kmet L and Macarthur C (2006). “Urban-rural differences in motor vehicle crash fatality and hospitalization rates among children and youth”. Accident Analysis and Prevention, 38(1): 122–127.

Li H, Graham DJ and Majumdar A (2011). “The effects of congestion charging on road traffic casualties: A causal analysis using difference-in-difference estimation”. Accident Analysis and Prevention, 49: 366–377.

Lord D, Washington SP and Ivan JN (2005). “Poisson, Poisson-gamma and zero-inflated regression models of motor vehicle crashes: Balancing statistical fit and theory”. Accident Analysis and Prevention, 37(1): 35–46.

Martins R and Veiga FJ (2014). “Does voter turnout affect the votes for the incumbent government?” European Journal of Political Economy, 36: 274–286.

Noland RB and Quddus MA (2004). “A spatially disaggregate analysis of road casualties in England”. Accident Analysis and Prevention, 36(6): 973–984.

Parry IWH, Walls M and Harrington W (2007). “Automobile externalities and policies”. Journal of Economic Literature, 43(2): 373–399.

Pereira AM and Andraz JM (2006). The Economic and Fiscal Impact of Toll-free Highways in Portugal. Lisbon, Portugal: Instituto para os Estudos sobre o Desenvolvimento.

_____ (2007). “On the economic and budgetary effects of the SCUTS—The Portuguese toll-free highways”. The Annals of Regional Science, 48(1): 321–338.

_____ (2010). Análise Custo Benefício Ex-Ante e Ex-Post das SCUT—Beira Interior, Beira Litoral e Alta, Grande Porto, e Interior Norte [Ex-Ante and Ex-Post Cost-Benefit Analysis of SCUT—Beira Interior, Beira Litoral and Alta, Grande Porto, and Interior Norte]. Lisbon, Portugal: Estradas de Portugal.

Ossenbruggen PJ, Pendharkar J and Ivan J (2001). “Roadway safety in rural and small urbanized areas”. Accident Analysis and Prevention, 33(4): 485–498.

Ruhm CJ (2015). “Recessions, healthy no more?” Journal of Health Economics, 42: 17–28.

Unidade Técnica de Acompanhamento de Projectos (UTAP) (2014). Relatório Annual das PPP—2013 [PPP Annual Report—2013]. Lisbon, Portugal: UTAP.

_____ (2015). Relatório Annual das PPP—2014 [PPP Annual Report—2014]. Lisbon, Portugal: UTAP.

Van den Bossche F and Wets G (2003). “Macro models in traffic safety and the DRAG family: Literature review”. Steunpunt Verkeersveiligheid bij Stijgende Mobiliteit RA-2003-08. Diepenbeek, Belgium: Steunpunt Verkeersveiligheid bij Stijgende Mobiliteit.

Wang C, Quddus MA and Ison SG (2009). “Impact of traffic congestion on road accidents: A spatial analysis of the M25 motorway in England”. Accident Analysis and Prevention, 41(4): 798–808.



  • There are currently no refbacks.

Copyright (c) 2020 Alfredo Marvão Pereira, Rui Marvão Pereira, João Pereira dos Santos

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Creative Commons License
This site is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.