OSRM vs pgRouting: What are the differences?

Introduction

This markdown document compares the key differences between OSRM and pgRouting, two popular routing libraries for geographic information systems (GIS). Both OSRM and pgRouting are open-source and provide functionality for routing and navigation. However, they differ in various aspects, as described below.

1. Routing Algorithm: OSRM (Open Source Routing Machine) uses the contraction hierarchies algorithm for routing. This algorithm pre-processes the road network to create a hierarchy of shortcuts, which enables faster route calculations. On the other hand, pgRouting offers multiple routing algorithms, including Dijkstra's algorithm, A* algorithm, and many more. Each algorithm has its own trade-offs in terms of performance and accuracy.

2. Data Storage: OSRM employs a highly optimized custom data storage format, which allows fast read access and efficient memory usage. It compresses the road network graph into a compact form, optimizing the storage and retrieval of routing information. Meanwhile, pgRouting uses the PostgreSQL database management system for data storage. It leverages the power of a relational database to store and query routing-related data efficiently.

3. Routing Constraints: OSRM provides limited support for routing constraints and requires the programmer to implement custom solutions for constraints like toll roads, vehicle restrictions, time-dependent routing, etc. On the other hand, pgRouting offers built-in support for various routing constraints, such as restrictions based on road attributes (e.g., road type, maximum speed), turn restrictions, and time-dependent routing.

4. Network Analysis Features: pgRouting offers a more extensive set of network analysis features compared to OSRM. It provides capabilities for calculating shortest paths, calculating driving distance matrices, finding the nearest facility, and solving the traveling salesman problem (TSP). OSRM, on the other hand, focuses primarily on efficient routing calculations, with limited support for network analysis beyond basic shortest-path calculations.

5. Integration with Existing Tools: pgRouting seamlessly integrates with the PostgreSQL ecosystem, allowing easy integration with other GIS tools and databases. It leverages the rich set of PostgreSQL features, including spatial indexing, spatial queries, and data manipulation capabilities. OSRM, although it can be used with various programming languages and frameworks, does not have the same level of integration with the broader GIS ecosystem.

6. Popularity and Community Support: OSRM has gained significant popularity and has an active community of users and contributors. It is widely adopted and used in various projects, which ensures ongoing development and support. pgRouting also has a dedicated user community, but it is relatively less known and popular compared to OSRM.

In Summary, OSRM and pgRouting differ in terms of routing algorithm, data storage, routing constraints, network analysis features, integration with existing tools, and popularity/community support.