In this research an effort is made to contribute to the goals of the Betonakkoord. This is done by optimising the design of big and bulky structures consisting out of a lot of concrete, namely lock heads. Lock heads are part of the navigation lock. The main research question answered in this thesis is phrased as follows: How can the design of lock heads be optimised to increase the sustainability?
Different alternatives have been generated to try to increase the sustainability. Each alternative has been compared to the lock head in Empel to test their feasibility. The following alternatives are considered: Inhomogeneous cross section, Prestressing and Hollow sections. From the alternative study it becomes clear that none of the alternatives are effective. The alternatives show no significant decrease in cost and MKI. Therefore, the alternatives are neglected in the remainder of the research. Based on this conclusion the following question arises: Is it possible to increase the sustainability of a lock head design based on commonly used design rules? In the next step of the research a parametric model is developed in order to answer this question. The parametric model design is based on the rules prescribed by the 'Handboek voor het ontwerpen van Schutsluizen' and the 'Richtlijnen Vaarwegen 2017'. The parametric model takes into account two types of gates, being a single leaf gate and a mitre gate. Again, the lock head in Empel has been used to validate the parametric model. From the parametric model it follows that in general a mitre gate is more cost effective and sustainable than a single leaf gate. This is because a mitre gate is generally shorter than a single leaf gate, so less materials are used and the construction pit can be smaller. Furthermore, the parametric model shows that the global stability check horizontal bearing capacity is a key parameter in the design of a lock head. To account for the horizontal bearing capacity the length and the weight of the lock head are important factors. The next step is to compare the lock head designs from the parametric model with the lock head design in Empel. The lock head design in Empel deviates from the rules prescribed by the 'Handboek voor het ontwerpen van Schutsluizen'. By deviating from the rules a more cost effective and sustainable design is acquired than both the designs from the parametric model. The lock head in Empel is shorter and lighter than the lock head designs from the parametric model. This is due to the fact that the lock head in Empel derives its horizontal bearing capacity from the lock chamber. In order to design a more cost effective and sustainable lock head it is advised to incorporate the lock chamber in the stability calculations. Hereby a shorter lock head can be achieved.