Highway engineering and language

It’s carnival time in Europe, so it seems appropriate to again say something about highway engineering and language, an area where engineers and carnival people seem to take a similar carefree approach. Put briefly there are at least four problems with technical language:

  • there are different languages in the world, so that say a German engineer will have a different term to an English engineer for the same highway element – for example, bike freeway and Radschnellweg
  • Two engineers working in the same language will use a different term for the same highway element. For example Wikipedia says that “A bike freeway, also known as a cycling superhighway, fast cycle route or bicycle highway, is an informal name for a bicycle path that is meant for long-distance traffic”
  • Engineers will not always check to see if an appropriate term exists, before they invent a new one.
  • Engineers often don’t define what the term they use actually mean, perhaps relying on the succinct Lewis Carroll explanation, as in ” “When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.”

A term such as Radschnellweg can simply be a group descriptor for several, more detailed types of the same highway element. Take for example the suggested details of a Radschnellverbindung (another term) from the publication “Qualitätsstandards für Radschnellverbindungen in Baden-Württemberg” – the document suggests four different design standards ….

Standard for bike expressways (built-up areas, non built-up areas); Reduced standard for bike expressways (built-up areas, non built-up areas)

…. and for each of these, 12 different types of Radschnellverbindung – which gives a total of 48 different design suggestions.


  • Engineers could begin by checking to see if a suitable term already exists before they invent a new one
  • All engineering terms to be expressed first in terms of one language (English ?)
  • All engineering terms to be defined

This suggests the preparation of a global, dictionary of engineering terms.

One concern about “too many terms” is that they can make things more complex for engineers than they really are. For example, there are many different terms for “cycle lanes” which I suspect refer to perhaps only ten or fewer, really different types.

Posted in uncategorized | Leave a comment

Egypt’s new capital city

Egypt is constructing a new capital city. The idea was announced in early 2015. Plans are for the city to cover an area of 700 sq.km, and have a total population of up to 7 million, which according to the Independent newspaper, would make it the biggest planned city ever.

It would be interesting to learn what design standards and concepts were being used for the design of the new city’s roads and streets.

See also Wikipedia: https://en.wikipedia.org/wiki/Proposed_new_capital_of_Egypt

Posted in uncategorized | Leave a comment

Jordan road standards

Jordan is a small country (ca. 10 million inhabitants) in the Middle East. Wikipedia writes that “Jordan is classified by the World Bank as an “upper-middle income” country. However, approximately 14.4% of the population lives below the national poverty line on a longterm basis (as of 2010)”. Road and street conditions in the capital city, Amman, and also in the country generally, do not appear to be very good. Part of the problem may be due to design standards. For example, writing in a presentation dated 2016 a representative of the MOT said that one of the actions needed to improve road safety in Jordan was the development of specific design standards of roads. The best information I have so far is that Jordan uses the USA’s AASHTO standards.

In 2017 local newspapers reported that the government was considering the development of a new city, which might eventually be a new home for some of the functions of the existing capital – if only because the new city’s roads and streets would likely work better than those in the existing Amman. However recent information (February 2019) suggests that this idea is more wishful thinking rather than a definitive policy.

Posted in uncategorized | Leave a comment

Bike lanes (4) definitions

You might think that it would be possible to get a general understanding of bike lanes if you start by checking out definitions of what they are. There are problems with this: even if we only look at documents which are written in the same language,  different guidelines use different terms for the same thing, and when they do define the same thing, they produce contradictory definitions. Also they don’t all describe the same sub-types of bike lane, so it’s difficult to get an overview of what the current state-of-the-art is.

Different terms for the same facility:

Examples of this are: bicycle lanes, cycle lanes, bike lanes, and (possibly) : separated bicycle lane, buffered cycle lane, protected cycle track

Different definitions for the same facility. For example, for bike lanes we can find:

  • Section of road pavement, adjacent and flush with traffic lane, designated by signage and pavement marking for exclusive use of cyclists. Also known as an exclusive bicycle lane. (ref. 2442)
  • Portions of a roadway set aside for bicycle use, with the lanes distinguished from the motor vehicle portion of the roadway by painted stripes, curbs, or parking block. (ref. 2396 USA)
  • Also known as conventional bike lanes, these are defned as a portion of the roadway that has been designated by striping, signage, and other pavement markings for the preferential or exclusive use of cyclists. Cycle lanes are typically on the right side of other vehicle lanes in the same direction or left side on one-way streets. Cyclists may have to leave the lane to pass other riders, to make turns, or to avoid obstacles. (ref. 2497)
  • Bike lanes (Class II bicycle facilities) are a portion of the road marked with a line, for use by bicyclists. They are always one­way facilities, with cyclists traveling in the same direction as motor vehicle traffic in the adjacent lane. Bike lanes often become dashed lines approaching an intersection to indicate that cyclists may shift lanes, and motor vehicles may pass through the lanes as needed for turning. Bike lanes are generally found on arterial roads and on major collectors. (ref.1994)

So, from these definitions engineers say that

  • A bike lane may or may not be for the exclusive use of cyclists
  • They are always one­way facilities  (but see ref. 2497, which includes discusses contraflow cycle lanes and contraflow cycle streets)
  • They may or may not be separated from the vehicle roadway by curbs or parking blocks


I begin to think that highway engineers are not able to collaborate, or to work within a shared, structured approach to their discipline; and perhaps also there is no incentive for them to collaborate internationally (and these days language should not be a barrier).

Maybe the task of developing a structured approach should be taken out of their hands and given to another discipline – librarians or botanists for example, who already have a structured international approach to their data.


  • 2497 – Global street design guide, NACTO, USA 2016
  • 2396 – Glossary of road design and construction terms, Nebraska DOR, USA
  • 2442 – AP-C87-15 Austroads Glossary of Terms, Austroads, 2015
  • 1994 – Pedestrian and bicycle planning – a guide to best practices, VTPI, Canada, 1994


Posted in comparative geometrics, highway design standards | Tagged , | Leave a comment

Bike lanes (3) – design zones

bike lane 3-1

I am aware of the desire for three- or four-dimensional road design as opposed to the more conventional approach of designing separately for horizontal alignment, vertical alignment, and the cross-section(s). However it does help to picture the road in two dimensions, for example to look at a plan view or a cross-section view.

An interesting idea with regard to both plan and cross-section views is the idea of transverse design zones. The graphic above, taken from ref. 2372, gives an idea of such design zones for separated bike lanes. The total width of roadway required can be calculated by adding the widths needed for each of the zones.

We can take the idea further, and say that each design zone consists of a number of micro-zones, as in the figure below.For an on-street bike lane zone there would be three micro-zones:
• kerb to cyclist-envelope
• cyclist-envelope
• cyclist-envelope to side of vehicle in the adjoining lane.

The idea of defining micro-zones and their widths has been around for some time in Germany, as in the following image, which is taken from a 1997 publication (ref. 177).

bike lane 3-3

Micro-zones and width of on-street cycle lanes

As a matter of interest, we can use this approach to calculate the width of an on-street cycle lane as:

bike lane 3-3


  1. Cyclist to vehicle distance: One source on Italy , dated July 2017, refers to a draft law which says the minimum distance to overtake a cyclist should be 1500mm (with more than Euro 300 suggested as penalty for not complying with this.. The same dimension is referred to in UK advice (see e.g. here) and German advice (see e.g. here).
  2. If a car, 2000mm wide, stays in the centre of its traffic lane (3500mm) , there would be 750mm available for the cyclist to vehicle envelope, meaning the minimum cycle lane width should be (3200mm – 750mm) = 2450mm wide…. which suggests that 1500mm wide cycle lanes are too narrow (and the figures for cyclist to vehicle width in the figure above are also too narrow).


  • Ref. 2372 Massachusetts separated bike lane planning and design guide 2015 (USA 2015)
  • Ref. 177 Strassenbau, Planung und Entwurf, Weisw, Durth u.a., (Germany, 1997)
Posted in basics | Tagged , | Leave a comment

Bike lanes (2) “style sheets”

In the previous post on bike lanes I said that it would be good to prepare an overview of cycle lanes, so that designers can pick the design best suited to their project; and I suggested that tThere are at least four different ways:

  1. By defining a structured listing of bike lane types
  2. By “good practice” style sheets
  3. By standardising terms
  4. By defining bike lane types

The list item (b) above refers to “style sheets”. What I mean by these is a single page of information which combines

  • a graphic of the bike lane
  • technical details such as road traffic flows and speeds
  • General text on which circumstances the bike lane type is most suited to

Such style sheets are (or should be) available for other road design elements as well. Here are two examples of “bike lane style sheets”, taken from different, English-language publications:


Washington County Bicycle facility design toolkit (USA 2012) – buffered bike lane

A good style sheet – images and photos on one side, technical details and general text on the other side, all on a single page.  The layout is used consistently in the document to present notes on other types of bike lanes.

bike lane 2-1

Los Angeles 2010 bicycle plan, technical design handbook (USA 2011) – bike lane with no on-street parking

Another good style sheet – images and photos on one side, technical details and general text on the other side, all on a single page.  The same layout is used in the document to present examples of other types of bike lanes.

bike lane 2-2

• Ref. 2402 Washington County Bicycle facility design toolkit (USA 2012)
• Ref. 917 Los Angeles 2010 bicycle plan, technical design handbook (USA 2011)

Posted in comparative geometrics, uncategorized | Tagged , , | Leave a comment

Bike lanes (1) a structure of types

bike lanes 1-1Bike lanes – in the general sense of “road space for use by cyclists” – have been around for quite a while. There is a Wikipedia article on the history of cycling infrastructure which says:

“The history of cycling infrastructure starts from shortly after the bike boom of the 1880s when the first short stretches of dedicated bicycle infrastructure were built ….”
But bike lanes have had a difficult history – at times, both motorists and cyclists objected to them. The same Wikipedia article says that In the 1930’s local branches of a UK cycling organisation held “mass meetings to reject the use of cycle tracks and of any suggestion that cyclists should be forced to use such devices”.

Today they are very much in fashion, and road designers have available a large number of standards and guidelines on their design. New problems are that there are so many different standards that it is difficult to get an overview of them; and they do not use the same terminology (even between documents published in the same language). Here are just a few terms for bike lanes taken from some English-language design standards / guides (seethe list of references below).:

Here are some terms used to describe different types of bike lane:
Separated bike lane (SBL)
One-way SBL Pair
Two-way SBL
Bicycle facilities
Shared lane markings
Shoulder bikeway
Conventional bike lane
Buffered bike lane
Cycle Track: Oneor two-way, at grade, protected with parking
Cycle Track: One or two-way, raised with mountable curb
Cycle Track: One or two-way, curb separated
Multi-use, off-street path
Bicycle boulevard
On-road bikeway
Buffered Bike Lanes (buffered from parking)
Buffered Bike Lanes (buffered from vehicles)
Shared travel lane (25 mph)
Separated path
Cycle track
Raised bike lane
Shared use path
Multi-use trail
Shared streets Cycle‐specific Infrastructure on Shared Streets
‘Bicycle Streets’ / Mixed Priority Treatment
Vehicle Restricted/‘Pedestrianised’ Areas
Home Zones
Segregated streets
Mandatory Cycle Lanes
Hybrid Cycle Lanes
Advisory Cycle Lanes

Simplifying method (a): structured listing
How can we prepare an overview of cycle lanes, so that designers can pick the design best suited to their project? There are at least four different ways:
a) By defining a structured listing of bike lane types
b) By “good practice” style sheets
c) By standardising terms
d) By defining bike lane types

For (a), a possible starter “structured listing” is included below. Probably it can only be developed further if we understand what the terms mean, and we can only do that if we understand how they are defined. For notes on (b,c,d) see the next blog posts.

bike lanes 1-2

• Ref. 986 ODOT Highway Design Manual Chapter 13 Pedestrian and Bicycle (USA 2012)
• Ref. 1937 Cardiff cycle design guide (UK 2011)
• Ref. 2372 Massachusetts separated bike lane planning and design guide 2015 (USA 2015)
• Ref. 2472 Washington County Bicycle facility design toolkit (USA 2012)


The first figure is from Massachusetts separated bike lane planning and design guide 2015 (USA 2015)

Posted in comparative geometrics, highway design standards, uncategorized | Tagged , , | Leave a comment

UK new road design standards

Highways England recently announced they are to release an updated set of road design standards in 2018 which will be used across the United Kingdom.

Posted in uncategorized | Leave a comment

Design standards

A textbook on highway engineering once said that there are three topics to consider in road design: the vehicle, the user and the road. We can add two more to this list:

  • Road standards – There are very many of these. They may contradict each other, be out of date or simply wrong
  • The person designing the road – who may misread the road standards, or make human errors when preparing the design

So for example, any investigation of a road traffic accident should include a look at the design of the road, the road standards used in preparing it, and perhaps the person / or organisation which designed it.

Posted in uncategorized | Leave a comment

More notes on road design standards (1)

Many countries publish “standards“, notes, advice and requirements related to the geometric design of roads. But as I have argued before (see for example here) there are too many of these standards. What makes life more difficult for engineers is that most of these standards suffer from one or more of the following problems:

  1. Traceability

A standard may suggest values for a parameter such as “side friction” – but does not say where the values come from. For all the reader may know, they may be based on research made in another country almost a century earlier. The reader should be able to trace back the suggested values to their original source.

  1. Completeness

The information presented may be incomplete. To take “side friction”  as an example again, perhaps the standard only gives values for one vehicle type, or the accompanying notes forget to mention that correction factors were applied to observed values.

  1. Terminology

The standard may not define the terms which it uses. For example, perhaps the values suggested for side friction refer to wet , surfaced roads, and are “maximum side friction factors accepted for design purposes” (or desirable maximum, or whatever).

  1. Inconsistency

Occasionally a standard may give different values for the same parameter, either internally or where the standard is part of a series of documents.

  1. Findability

Sometimes, suggested values are hidden in a dense jungle of explanatory notes, or spread through different sections of the same document; or the document may not have a table of contents. This makes it difficult to find values you are interested in.

  1. Technical

Many of the parameters involved in road geometric design can be associated with different design approaches, theories and concepts. Some of these approaches and concepts may be out of date, or doubtful, or perhaps not yet widely accepted.

Posted in comparative geometrics, highway design standards, road design, uncategorized | Tagged | Leave a comment