Additional Safety Measures for Movable Bridges, A Bridge Too Far? A Calculated Approach on Proportional Safety for Movable Bridges in the Netherlands

Abstract

This article explores a proportional safety approach for movable bridges, aligning with the core principles of Dutch safety policies: the use of the Dutch norm for an individual risk (IR) of one fatality per hundred thousand people exposed (denoted as IR = 10-5) and a reasonable investment maximum of € 80.000, - per gained disability adjusted life year (DALY). Based on the actual history of accidents the individual risk for people using movable bridges is around 10-7 and thus easily meets the Dutch norm. Movable bridges in the Netherlands are thus more than ‘safe enough’ and do not require extra investments in safety measures. If the municipal and provincial authorities in charge of movable bridges do decide to invest in extra safety measures, a reasonable maximum budget is € 2.2 million a year for all 1.500 movable bridges. Here it is assumed that the newly implemented safety measures verifiably lead to preventing all casualties.