Optimization to reduce waiting times at locks

Cargo transport is important for supplies of goods and food worldwide. The goods and food are transported by inland transport modes, like road, railway and inland waterway transport. Due to a growth in world population the demand of goods and food increase, which results in an increase in cargo transport. More transport leads to more traffic on roads, railway and inland waterways. Roads and railways are at their limits of capacity, while inland waterways have the ability for an increase of waterway traffic. The European waterway network for inland transport is wide and connects sea ports and the European hinterland with each other. While inland waterway transport is cheaper and slower compared to road and railway transport, it is also less reliable than the other transport modes. The reliability is the ability to perform and maintain the agreements made between actors involved in the cargo transport during normal circumstances, as well as during unexpected circumstances, like delays. A disadvantage for inland waterway navigation is the locks in the waterway network. Locks maintain the water on a certain level, so that inland vessels can navigate without the risk of grounding. Locks also cause congestions when the lock capacity is lower than the amount of vessels that want to pass the lock during a certain time. These congestions cause delays for the vessels, which do not increase the reliability of the waterway transport mode. To stimulate the inland waterway transport, so that cargo transport over water will become more compatible with road and railway transport, the reliability for inland waterway transport must be increased. This can be done by decreasing the waiting times at the locks in the waterways. The interarrival times of inland vessels have an influence on the waiting times for vessels at locks. So when the arrival times of vessels at a lock are controlled, the waiting times can be controlled. A simulation model is designed to simulate what the effect of controlled arrivals of vessels is on the waiting time at locks. The simulation model is able to adjust the velocities of all vessels that navigate on the waterway towards the lock. With the adjustments in velocity of a vessels, the arrival time of that vessel is controlled by the model. The adjustment in velocity can let the vessel navigate faster and slower. When a vessel slows down it´s travel time on the waterway increases. A lower velocity and a longer travel time means that the fuel costs decrease and the operation time increases. That could result in a higher total travel costs. Therefore the simulation model can minimize the waiting times or the travel costs. With the minimization of costs the waiting time is minimized as well, due to the fixed operating costs a vessel has, which are the travel costs without fuel costs. Variables in the simulation model are the length of the controlled waterway, the service time of the lock and the lock capacity. The length of the controlled waterway determines the size of the system and the area where the vessels are controlled, the service time is the time it takes to pass the lock and the lock capacity determines the maximum number of vessels that can enter the lock chamber during one service run. As an input for the simulation model each vessel has its own entering velocity and entering time during a day. The entering velocities of the vessel are between 10 and 20 km/h and can be adjusted between 5 km/h and 110% of the entering velocity of the vessel. The entering time is distributed by a Weibull distribution. Since inland waterway transport is not yet a full 24/7 industry, the distribution is in such way that the majority of the daily vessels that pass the lock will enter the system between 06:00 and 20:00 hour. The settings used for the variables in the simulations are based on situations at four locks between the two largest sea ports in Europe, which are Rotterdam and Antwerp. The locks are the Volkerak, Krammer, Hansweert and Kreekrak lock and the waiting times at those lock are expected to be as long as 3 hours in the next decade. The output of the simulation model are waiting times at the lock and the total travel costs for each vessel in an optimized situation, which is a situation with minimized waiting time or travel costs. Optimized results of the simulation model are compared with the simulations that represent the four locks with the expected waiting times. The simulation model shows a reduction in waiting times of more than 80% compared to the expected waiting times for the next decade. If this can be achieved in reality the inland waterway transport mode can be stimulated due to smaller unexpected delays and an increased reliability.Mechanical, Maritime and Materials EngineeringMarine and Transport TechnologyTransport Engineering and Logistics2012.TEL.771