Route Types: Geometry

In my effort to describe the different bus lines proposed in my South Vienna´s Busses I researched the terminology for different types of public transportation routes. Apparently, there is no standard terminology for many of the routing options and some that I can think of are not accurately described in one source. Now maybe I am incorrect and there is an author that has gone to the effort to describe all the different types of routes in a book that I do not know of or in a language that I do not speak. Nevertheless, I am going to attempt to describe what different kind properties public transportation routes can have in this post and hope that my terminology resonates with urban planners. Since the terminology of the existing radial, circular, tangential and diameter names derive from Latin words describing geometry, I tried to name missing terms also from Latin words that describe their geometry. Sources that describe the different route types are linked in the descriptions. Finally, I am a visual person who appreciates pictures that convey a concept, so each route type will have a fictional example drawn over an adapted map vectorized by Furfur. The theoretical descriptions often include the term town centre, however this can be replaced with city centre, interchange or transportation hub.

 

Radial route

A radial route (arterial route) links a central point in a town to the periphery of that town.

 

Examples:

• Singapore’s North East Line

 

Diameter Route

A diameter route (through route, cross-city route) links one side of a town with the opposite side through the town centre.  For a route that connects one side of a city to another without going through the town centre see secantial route. For a route that connects a part of a town with another and orbits around the town centre see tangential route.

 

Examples:

• Tokyo Metro Tōzai Line

 

Tangential route

A tangential route (orbital route, crosstown route) links outer parts of a town to each other but does not serve the town centre, instead it is routed in an arc around it. The intersections of tangential routes to radial routes is perpendicular. For a route that connects one side of a city to another but not in an arc around the town centre see secantial route.  For a tangential route that completes a circle around the town centre, see circumferential route. In combination with diameter and radial routes, tangential routes can form polar transportation networks.

 

Examples:

• Vienna’s Vorortelinie S45

 

Secantial Route

A secantial route (crosstown route) connects one side of a town to another directly. A special kind of secantial route is the diameter route that passes through the town centre. For a route that does not pass through the city centre but arcs around it see tangential route. Secantial routes perpendicular and parallel to each other form square grid transportation networks. Secantial routes with 60° angles to each other form triangular grid transportation networks.

 

Examples:

• Toronto’s Line 5 Eglinton

 

Circular Route

A circular route (ring route) follows a route in a town that roughly forms a circle or square as opposed to a line. A public transportation line may serve the route in only one direction (clock-wise or anti clock-wise) or in both directions. A circular route may orbit around the town centre, see further circumferential route below. A route may include a circular section and also a radial or tangential section, see further lacial route below.

 

Examples:

• Madrid’s Línea 12  MetroSur

 

Lacial Route

A lacial route (lasso route, noose route, tennis racket route, loop route) incorporates a circular section and a direct section. Depending on the ratio between the circular section and direct section, a lacial route type can be divided into a lacial pan route, a lacial ladle route or a lacial spoon route.

 

Lacial Pan Route

A lacial pan route (as described by metrobits) combines a short direct route together with a large circular route. The circular either orbits or arcs around the town centre or the direct section starts from the town centre and the circular section serves peripheral parts of the town.

 

Examples:

• JFK AirTrain
• London’s Circle Line

 

Lacial Ladle Route

A lacial ladle route consists of a long direct section (usually a radial route) and a small to medium circular section. The circular section is used to connect dispersed points of interest in a town centre area (e.g. rail station, main square and business district). An advantage of such a route is that passengers are more dispersed and not concentrated in central interchange that must dimensioned for large transfer volumes.

 

Examples:

• Night bus lines of Vienna

 

Lacial Spoon Route

A lacial spoon route incorporates a small circular section or terminal loop at the end of another route type.

 

Examples:

• Piccadilly Line – Heathrow Terminal Loop, London
• Many of the Berlin tram lines

 

Parallel Route Section

A parallel route section consists of a return route section on a offset parallel path. This can be due to one way streets, road width limits, favourable turn options or to serve a larger area of a town via a lacial section.

 

Examples:

• By the Nice Tram T1 between Gorbella and Valrose Uni.

 

Arcantial Route

An arcantial route (from arcus, arch route, bow route, curved route) combines two radial routes that are not across from each other but at an angle to each other (typically 30° to 160°) via a tangential section usually orbiting or through a town centre.

 

Examples:

• Vienna Subway Line U4 and U1
• Nice Tram T1

• Toronto’s Line 1 Yonge–University

 

Circumferential Route

A circumferential route is a circular route that orbits the town centre.

 

Circumferential Peripheral Route

A circumferential route (periphery route) is a circumferential route that serves the periphery of a the town. In combination with diameter and radial routes, circumferential routes can form polar transportation networks.

 

Examples:

• Moscow’s Subway line 5 and 14
• Glasgow
• Beijing Line 2 and  Line 10

 

 Linear Route

A linear route (trunk route, main line, stammstrecke) serves parts of a town in roughly a straight line without detours. For a direct route that passes through the town centre see diameter route. See also secantial route.

 

Maeander Route

A maeander route (feeder route, s-route, snake route) connects many parts of a town by forming detours to the left and right of it’s generally direction. Thus a public transportation line serving the route can cover a large area and many points of interest with out the necessity of a transfer. Often a maeander route will be combined with a direct route of a faster transportation mode and fulfils the role of transporting passengers to the direct route (feeder).

Examples:

• Istanbul T1 Tram

 

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Notes:

I included space for advantages, disadvantages and examples under each route type. I would appreciate route examples or opinions on advantages and disadvantages.

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Edit: 2017.12.11 added examples removed disadvantages and advantages. 2017.12.13: adding orbital route to tangential route.
Edit: 2018.04.02 named Direct Route to Linear Route.

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Further Reading:

• Jerret Walker wrote in his article The Power and Pleasure of Grids about the advantages of grid versus he classic “radial” or polar grid, also called a “spider web”.
• Mike Rohde has a list of METRO RINGS AND LOOPS.
• Urban Bus Planning Toolkit by the World Bank Group and PPIAF.