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Traveler routers (also known as public transport route planners, and historically slightly incorrectly journey planners and intermodal journey planners) takes as input locations A and B and some other optional parameters and it finds the optimal connection given the parameters in a transportation network or sets of transportation networks.

The traveller router services often include a price comparison service where you can compare the variables of alternative modes of transport, travel dates and carriers.

History

Prior to 1970s

• Travel agents had to rely on printed travel timetable and lodging listings and telephone and work out the connections manually.

1970s and 1980s

• Since the 1970s travel agents have had digital journey planners at their disposal. Not really traveler router since the ultimate consumer could not see the results directly but had to purchase services of the travel agent to find out about his/her travel possibilities.

1990s

• The first known publicly accessible traveler router is the Reiseauskunft.bahn.de developed by Deutsche Bahn in the 1990s. Reiseauskunft today is Europe-wide multimodal traveler router and also includes bus traffic for many areas. It has some very advanced features. When booking travel in Germany this traveler router is for example able to guide you about the platform numbers you need to get to/from. Tickets for connections may be bought from Deutsche Bahn for their service and for all European rail routes via 3rd parties set up by entities like SNCF.

2000s

• In the early 2000s various applications of this idea to local traffic emerged with popular implementations for cities like London and Helsinki. Dot-com boom also saw an explosion in services offering you to search air transport network based on price, number of landings, and speed among other criteria.

2010s

• In the 2010s many of the smaller players have been squeezed out due to Google Transit. It has also seen the emergence of global metasearch engines like Rome2rio (.com) is a worldwide multimodal traveller router that displays realistic prices. The prices it gives are slightly inflated from what you would as a local expect to get it for but they are hitting the mark on what a tourist will pay for booked-on-the-go ticket. No direct booking. * Google Transit (google.com) is a multimodal traveller router with wide coverage but no price information or booking possibility.

Current technology

The problem of getting the consumer from A to B is technically

• A traversal problem in a directed graph network
• with (time and money) costs for the edges (taking certain connection requires N time, taking certain route you must purchase appropriate ticket)
• validity times for edges (You cannot board a vehicle if it went already)
• the machine does not much care if it is multimodal or not since as long as it has the data sets available

A slightly modified Dijkstra's algorithm has been successfully been used to solve the problem.

Future

Currently there is ongoing work to making a copyleft alternative to various commercial engines that are costing the municipalities money. Finnish transport authorities Trafi (national beta) and HSL (Metropolitan Helsinki area) beta are collaborating with principles of open source, open standards and open data. More information on the Digitransit effort here.

A likely development with traveler routers is that someone integrates them primarily with ridesharing apps and secondarily with carsharing apps enabling the traveling consumer to get questions "How is the public transport regarding my travel plan?", '"Are there peer-to-peer ridesharing cars going my way?" and "Are there any carsharing cars to which I have subscription to nearby?" answered from single app.

See also

• Peer-to-peer ridesharing services incl. slugging, hitchhiking, real-time ridesharing services and transportation network companies like Uber and Haxi.
• Carsharing services (with subscription possiblities for travelers)