A bottom up model to estimate the emission levels of public transport systems based on General Transit Feed Specification (GTFS) data. The package requires two main inputs: i) Public transport data in the GTFS standard format; and ii) Some basic information on fleet characteristics such as fleet age, technology, fuel and Euro stage. As it stands, the package estimates several pollutants at high spatial and temporal resolutions. Pollution levels can be calculated for specific transport routes, trips, time of the day or for the transport system as a whole. The output with emission estimates can be extracted in different formats, supporting analysis on how emission levels vary across space, time and by fleet characteristics. A full description of the methods used in the 'gtfs2emis' model is presented in Vieira, J. P. B.; Pereira, R. H. M.; Andrade, P. R. (2022) <doi:10.31219/osf.io/8m2cy>.

Convert general transit feed specification (GTFS) data to global positioning system (GPS) records in 'data.table' format. It also has some functions to subset GTFS data in time and space and to convert both representations to simple feature format.

Tools for the development of packages related to General
    Transit Feed Specification (GTFS) files. Establishes a standard for
    representing GTFS feeds using R data types. Provides fast and flexible
    functions to read and write GTFS feeds while sticking to this
    standard. Defines a basic 'gtfs' class which is meant to be extended
    by packages that depend on it. And offers utility functions that
    support checking the structure of GTFS objects.

Use 'GTFS' (General Transit Feed Specification) data for routing
    from nominated start and end stations, for extracting 'isochrones', and
    travel times from any nominated start station to all other stations.

Utility functions to read, manipulate, analyse and write
    transit feeds in the General Transit Feed Specification (GTFS) data
    format.

Insert tables created by the 'gt' R package into 'Microsoft Word' 
    documents. This gives users the ability to add to their existing word documents
    the tables made in 'gt' using the familiar 'officer' package and syntax from
    the 'officeverse'.