Applying Operations Research techniques to planning of train shunting

In this paper, we discuss a model-based algorithmic approach for supporting planners in the creation of shunt plans for passenger trains. The approach provides an example of a mathematical model and a corresponding solution approach for model based support. We introduce a four-step solution approach and we discuss how the planners are supported by this approach. Finally, we present computational results for these steps and give some suggestions for further research

Real-time train driver rescheduling by actor-agent techniques

Passenger railway operations are based on an extensive planning process for generating the timetable, the rolling stock circulation, and the crew duties for train drivers and conductors. In particular, crew scheduling is a complex process. After the planning process has been completed, the plans are carried out in the real-time operations. Preferably, the plans are carried out as scheduled. However, in case of delays of trains or large disruptions of the railway system, the timetable, the rolling stock circulation and the crew duties may not be feasible anymore and must be rescheduled. This paper presents a method based on multi-agent techniques to solve the train driver rescheduling problem in case of a large disruption. It assumes that the timetable and the rolling stock have been rescheduled already based on an incident scenario. In the crew rescheduling model, each train driver is represented by a driver-agent. A driver-agent whose duty has become infeasible by the disruption starts a recursive task exchange process with the other driver-agents in order to solve this infeasibility. The task exchange process is supported by a route-analyzer-agent, which determines whether a proposed task exchange is feasible, conditionally feasible, or not feasible. The task exchange process is guided by several cost parameters, and the aim is to find a feasible set of duties at minimal total cost. The train driver rescheduling method was tested on several realistic disruption instances of Netherlands Railways (NS), the main operator of passenger trains in the Netherlands. In general the rescheduling method finds an appropriate set of rescheduled duties in a short amount of time. This research was carried out in close cooperation by NS and the D-CIS Lab

Dutch randomized trial comparing standard catheter-directed thrombolysis versus Ultrasound-accElerated Thrombolysis for thromboembolic infrainguinal disease (DUET): design and rationale

Background: The use of thrombolytic therapy in the treatment of thrombosed infrainguinal native arteries and bypass grafts has increased over the years. Main limitation of this treatment modality, however, is the occurrence of bleeding complications. Low intensity ultrasound (US) has been shown to accelerate enzymatic thrombolysis, thereby reducing therapy time. So far, no randomized trials have investigated the application of US-accelerated thrombolysis in the treatment of thrombosed infra-inguinal native arteries or bypass grafts. The DUET study (Dutch randomized trial comparing standard catheter-directed thrombolysis versus Ultrasound-accElerated Thrombolysis for thrombo-embolic infrainguinal disease) is designed to assess whether US-accelerated thrombolysis will reduce therapy time significantly compared with standard catheter-directed thrombolysis.Methods/design: Sixty adult patients with recently (between 1 and 7 weeks) thrombosed infrainguinal native arteries or bypass grafts with acute limb ischemia class I or IIa, according to the Rutherford classification for acute ischemia, will be randomly allocated to either standard thrombolysis (group A) or US-accelerated thrombolysis (group B). Patients will be recruited from 5 teaching hospitals in the Netherlands during a 2-year period. The primary endpoint is the duration of catheter-directed thrombolysis needed for uninterrupted flow in the thrombosed infrainguinal native artery or bypass graft, with outflow through at least 1 crural artery.Discussion: The DUET study is a randomized controlled trial that will provide evidence of whether US-accelerated thrombolysis will significantly reduce therapy time in patients with recently thrombosed infrainguinal native arteries or bypass grafts, without an increase in complications. Trial registration: Current Controlled Trials ISRCTN72676102

Drug coated balloon supported Supera stent versus Supera stent in intermediate and long-segment lesions of the superficial femoral artery:2-year results of the RAPID Trial

BACKGROUND: Endovascular treatment of occlusive disease of the superficial femoral artery (SFA) has evolved from plain old balloon angioplasty (MBA) through primary stenting strategy to drug eluting technology-based approach. The RAPID Trial investigates the added value of drug coated balloons (DCB, Legflow) in a primary stenting strategy (Supera stent) for intermediate (5-15 cm) and long segment (&gt;15 cm) SFA lesions.METHODS: In this multicenter, patient-blinded trial, 160 patients with intermittent claudication, ischemic rest pain, or tissue loss due to intermediate or long SFA lesions were randomized (1:1) between Supera + DCB and Supera. Primary endpoint was primary patency at 2 years, defined as freedom from restenosis on duplex ultrasound (peak systolic velocity ratioRESULTS: At 2 years, primary patency was 55.1% (95% CI: 43.1-67.1%) in the Supera + DCB group versus 48.3% (95% CI: 35.6-61.0%) in the Supera group (P=0.957). Per protocol analysis showed a primary patency rate of 60.9% (95% CI: 48.6-73.2%) in the Supera + DCB group versus 49.8% (95% CI: 36.9-62.7%) in the Supera group (P=0.469). The overall mortality rate was 5% in both groups (P=0.975). Sustained functional improvement was similar in both groups.CONCLUSIONS: The 2-year results in the current trial of a primary Supera stenting strategy are consistent with other trials reporting on treatment of intermediate and long SFA lesions. A DCB supported Supera stent strategy did not improve patency rate compared to a Supera stent only strategy.</p