Understanding road geometrics (2)

Road cross-sections are a form of picture to show technical information. The information they aim to show can vary, covering either location of utilities lines, road pavement structure, or the transverse composition of the road – lanes, footways, medians etc. The following give four examples of road cross-sections which are taken from three different road design standards. I add some comments following each image. The authors of the documents intended the images to be read as part of the whole document, and so my comments may be a little unfair.

Australia, VicRoads supplement part 3 – geometric design; VicRoads 2011 (Ref. 585)

x-sections 11

Comment

A very basic form of illustration. Good: the reference to traffic flow and the summary description of the cross-section. Missing: no mention of design speed

Germany, RAA Richtlinien für die Anlage von Autobahnen; FGSV 2008 (Ref. 1615)

x-sections 12

Comment

A more detailed picture. Good: dimensions and details for more of the cross-section modules, such as kerbs and lande markings. Missing: no direct mention of design speed or traffic flow.

Ethiopia, Design manual for low volume roads, part-B; Ethiopian Roads Authority 2011 (Ref. 308)

x-sections 13

Comment

A simple image but with an associated table with detailed data. Good: table with additional details. Missing: no direct mention of design speed, traffic flow or lane width.

India, Street design guidelines …. for equitable distribution of road space; UTTIPEC 2010 (Ref. 450)

x-sections 14

Comment

An image which combines cross-section information with vehicles, arguably giving a better understanding of what the road consists of. Good: use of vehicle images, reference to design speed and road function. Missing: text is difficult to read (this applies to the image in the source document as well).

Comment

I like the Ethiopia example, with its table of supplementary details, although for more complex cross-sections IMO a visual which shows vehicles on the road would be preferable.

References

308 – Ethiopia, Design manual for low volume roads, part-B; Ethiopian Roads Authority 2011

585 – Australia, VicRoads supplement part 3 – geometric design; VicRoads 2011

1450 – India, Street design guidelines …. for equitable distribution of road space; UTTIPEC 2010

1615 – Germany, RAA Richtlinien für die Anlage von Autobahnen; FGSV 2008

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About roadnotes

Robert Bartlett is an international consultant with over 30 years of professional experience as a highway and traffic engineer with leading companies and organisations in several countries, including Germany, China (Hong Kong), Qatar and the UK. Specialised in urban studies, transport and the use of GIS, research has included new ideas on subjects such as the study of social justice using GIS, the dimensions of vehicles, and comparative geometrics (highways and transport).
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