The Evaluation of Route Guidance Systems

BACKGROUND We were commissioned by the Transport and Road Research Laboratory to: "collaborate with the German government and their representatives who are responsible for conducting the LISB trial in Berlin in order to produce an agreed methodology, which is acceptable in both Germany and the UK, for assessing the automatic route guidance systems which will be provided in Berlin and London." The brief suggested a number of aspects to be included, and required detailed proposals, timescales and costs for implementation in London. 1.1.2 The background to the brief lies in decisions to introduce pilot automatic route guidance systems in the two cities. The principles of the systems are similar, and have been described in detail elsewhere (Jeffery, 1987). In brief, they involve : (i) a central computer which retains information on a specified road network, which is updated using real time information from the equipment users; (ii) infra red beacons at selected junctions which transmit information to equipped vehicles and receive information from those vehicles; (iii) in-vehicle equipment which includes a dead-reckoning system for position finding, a device for requesting guidance and specifying the destination, a micro-computer which selects the optimal route, and a display which indicates when a turn is required on the main network, and the compass direction and distance to the final destination; iv) transmission from the equipped vehicles of origin, requested destination, links used since passing the last beacon and, for each link, the time of entry and departure and time spent delayed. It is this travel time information which is used to update the central computer's knowledge of the best routes. (Continues..

Financial incentives in disability insurance in the Netherlands

In this paper, we assess the impact of financial incentives on the inflow in the public Disability Insurance (DI) scheme in the Netherlands. For this matter, the variation in replacement rates over different sectors is exploited to estimate the probability of DI enrolment over a sample of employees from the Dutch Income Panel (1996-2000). On the basis of these administrative data, we find a point estimate of the elasticity of DI enrolment with respect to the DI wealth rate of 2.5.

The impact of reforms on labour market exit probabilities

Early retirement schemes and disability insurance in the Netherlands have both been reformed during the past decades. The reforms have increased incentives to continue working and have decreased the substitution between early retirement and disability. This study investigates the impact of the reforms on labour market exit probabilities We use administrative data for workers in the Dutch health care sector between 1999 and 2006. We estimate a multinomial Logit model for transitions out of the labour force. The empirical results suggest that the reforms have been effective, as the labour market participation rate of the elderly has increased. The concept of substitute pathways into retirement seems less relevant today as the results confirm that disability insurance is closed off as an early retirement exit route. Key words: early retirement, disability insurance, labour supply �

The Interaction Between Signal Control and Traffic Assignment: An Introduction.

Traffic assignment and signal control are generally considered separately. Proper recognition of the interaction that exist between assignment and signal control introduces a number of theoretical and computational complexities; on the other hand considerable network improvements can be achieved. This report introduces the problem of interaction between signal control and traffic assignment, reviews related issues and previous work. It discusses signal control as a network design problem, and it makes a case for the iterative assignment control procedure for its approximate solution

The Interaction Between Route Guidance and Signal Control: Model Results.

A multiple user class assignment model is developed to simulate the interaction between a route guidance system and an urban traffic control system. For two real- life networks of Leeds and Southampton four basic scenarios are investigated: current situation; - expected situation with route guidance but without interaction with the traffic control system; - expected situation with route guidance and with interaction with the traffic control system; - optimum future situation with 100% take-up and compliance with system optimal guidance and delay minimising signal control. The computed extra travel time savings of an integration of route guidance and signal control are of a similar magnitude as those of a route guidance system alone. With static demand delay minimisation performs best, but when demand is dynamically increasing Smith's Po policy gives rise to lowest network travel times. The degrading effect of imperfect advice or non-compliance is small at realistic levels of take-up of up to 25%. Along the same line, the benefits of system optimal guidance are also modest (in the order of less than 1%) when take-up of guidance is less than 25%

The Decline of Early Retirement Pathways in the Netherlands: An Empirical Analysis for the Health Care Sector

Early retirement schemes and disability insurance in the Netherlands have both been reformed during the past decades. The reforms have increased incentives to continue working and have decreased the substitution between early retirement and disability. This study investigates the impact of the reforms on labour market exit probabilities. We use administrative data for workers in the Dutch health care sector between 1999 and 2006. We estimate a multinomial Logit model for transitions out of the labour force. The empirical results suggest that the reforms have been effective, as the labour market participation rate of the elderly has increased. The concept of substitute pathways into retirement seems less relevant today as the results confirm that disability insurance is closed off as an early retirement exit route.early retirement, disability insurance, labour supply

Relaciones espaciales entre el bisonte americano Bison bison y el ganado vacuno en un medio de montaña

Restoration of American bison (Bison bison) to montane environments where they once occurred requires information on ecological relationships with domestic cattle (Bos taurus) that now live there. Comparisons of the foraging distributions of sympatric bison and cattle in a 375–ha basin revealed that cattle were constrained by slope and distance from water, especially vertical distance, whereas bison responded mostly to forage availability. Cattle appeared to be central place foragers oriented around water and followed a strategy of meeting their energetic needs with the least cost. Bison, in contrast, appeared to be energy maximizers that moved often in response to forage availability. The result was relatively little overlap (29%) in spatial distributions. If bison replace cattle in montane environments, managers can expect a more even distribution of grazing pressure. Bison and cattle might be managed sympatrically; their spatial distributions may be sufficiently different to minimize competition for food, and the risk of interspecific disease transmission as well.La reintroducción del bisonte americano (Bison bison) en un ambiente de montaña donde ya había vivido antes requiere información acerca de las relaciones ecológicas con el ganado vacuno (Bos taurus) que ahora habita en ese lugar. La comparación de las distribuciones de forrajeo del bisonte con las de la vaca en una cuenca de 375 ha demostraron que la vaca estaba limitada por la inclinación del terreno y la distancia al agua, especialmente la distancia vertical, mientras que el bisonte lo estaba principalmente por la disponibilidad de pasto. La vaca mostró clara orientación a pacer principalmente alrededor del agua y siguió una estrategia de obtención de sus necesidades energéticas con el mínimo coste. En contraste, el bisonte se mostró maximizador de energía, efectuando frecuentes desplazamientos en función de la disponibilidad de pastos. El resultado dio una coincidencia relativamente reducida (29%) en las distribuciones espaciales. Si el bisonte sustituye al ganado en medios de montaña, puede esperarse una mejor distribución de la presión sobre los pastos. Los bisontes y el ganado vacuno pueden convivir en la misma área geográfica, puesto que sus distribuciones espaciales son suficientemente diferentes para minimizar la competencia por el alimento, así como el riesgo de transmisión interespecífica de enfermedades

The Influence of Cost Assumptions on Properties of the Combined Assignment Control Problems.

The uniqueness and existence of a solution to the combined traffic assignment/signal control problem is investigated, particularly with respect to the cost functions used. The two cost functions investigated are the polynomial BPR function and Webster's two term cost function. Properties of three well-known signal control policies are investigated, and a number of new policies are developed, which guarantee a unique solution to the combined problem. The comparative performance of these policies is tested with respect to uniqueness of the resulting green times and total network travel times at the solution. To this end a streamlined version of the iterative assignment control procedure is developed and applied to three networks. It is found that potential theoretical uniqueness and existence problems do not necessarily occur in practical tests, and that enforcement of theoretical properties on signal control policies renders them rather inefficient