Abstract
Index structures are fast-access methods. In the past, they were often used to minimise fetch operations to external storage devices (secondary memory). Nowadays, this also holds for increasingly large amounts of data residing in main-memory (primary memory). Examples of software that deals with this fact are in-memory databases and mobile device applications. Within this scope, this paper focuses on index structures to store, access and delete interval-based time-dependent (temporal) data from very large datasets, in the most efficient way. Index structures for this domain have specific characteristics, given the nature of time and the requirement to index time intervals. This work presents an open-source time-efficiency focused variant of the original Interval B+ tree. We designate this variant Improved Interval B+ tree (I2B+ tree). Our contribution adds to the performance of the delete operation by reducing the amount of traversed nodes to access siblings. We performed an extensive analysis of insert, range queries and deletion operations, using multiple datasets with growing volumes of data, distinct temporal distributions and tree parameters (time-split and node order). Results of the experiments validate the logarithmic performance of these operations and propose the best-observed tree parameter ranges.

Abstract
Advanced Traveller Information Systems (ATIS) have seen a steady increase in popularity in the last decades among urban users. By providing travellers with relevant information, these systems have the ability to considerably improve traffic flow, but are limited by their penetration rate among the city's population. In this work we put forward HERMES1, a tool to facilitate the evaluation of road networks through simulation with different ATIS and with different levels of information percolation among users. The usefulness of such a tool stems from the quantification of the extent to which an ATIS can improve total travel time and road utilisation by means of experimenting with simulation scenarios. This tool operates at a mesoscopic level, in which single users may be represented independently from each other, nonetheless are rather considered to operate at their macroscopic interactions with the network. We also illustrate example use cases for the tool on the motorway network between the Portuguese cities of Lisbon and Porto. © 2019 IEEE.