Time-dependent Hyperstar algorithm for robust vehicle navigation in time-dependent stochastic road networks.

The vehicle navigation problem studied in Bell (2009) is revisited and a time-dependent reverse Hyperstar algorithm is presented. This minimises the expected time of arrival at the destination, and all intermediate nodes, where expectation is based on a pessimistic (or risk-averse) view of unknown link delays. This may also be regarded as a hyperpath version of the Chabini and Lan (2002) algorithm, which itself is a time-dependent A* algorithm. Links are assigned undelayed travel times and maximum delays, both of which are potentially functions of the time of arrival at the respective link. The driver seeks probabilities for link use that minimise his/her maximum exposure to delay on the approach to each node, leading to the determination of the pessimistic expected time of arrival. Since the context considered is vehicle navigation where the driver is not making repeated trips, the probability of link use may be interpreted as a measure of link attractiveness, so a link with a zero probability of use is unattractive while a link with a probability of use equal to one will have no attractive alternatives. A solution algorithm is presented and proven to solve the problem provided the node potentials are feasible and a FIFO condition applies for undelayed link travel times. The paper concludes with a numerical example.

Roll Project Rich Vehicle Routing benchmark problems.

This document describes a large set of Benchmark Problem Instances for the Rich Vehicle Routing Problem. All files are supplied as a single compressed (zipped) archive containing the instances, in XML format, an Object-Oriented Model supplied in XSD format, documentation and an XML parser written in Java to ease use.

Third Sector Experiences of Work Programme Delivery.

This paper explores the organisational experiences of governmental policy change and implementation on the third sector. Using a four-year longitudinal study of 13 third sector organisations (TSOs) it provides evidence based on the experiences of, and effects on, third sector organisations involved in the UK’s Work Programme in Scotland. The paper explores third sector experiences of the Work Programme during the preparation and introductory phase, as well as the effects of subsequent Work Programme implementation. By gathering evidence contemporaneously and longitudinally a unique in-depth analysis is provided of the introduction and implementation of a major new policy. The resource cost and challenges to third sector ways of working for the organisations in the Work Programme supply chain, as well as those not in the supply chain, are considered. The paper considers some of the responses adopted by the third sector to manage the opportunities and challenges presented to them through the implementation of the Work Programme. The paper also reflects on the broader context of the employability services landscape and raises questions as to whether, as a result of the manner in which the Work Programme was contracted, there is evidence of a move towards service homogenisation, challenging perceived TSO characteristics of service innovation and personalisation.