Saturday, 16 November 2019

CD195 Designing For Cycle Traffic

A couple of weeks back I wrote about how the Design Manual for Roads & Bridges (DMRB) was changing and this week I'm doing to have a dig through CD195 - Designing for Cycle Traffic.

The first thing to say is the DMRB is a standard to be used on Highways England and devolved administration schemes. It is a useful document for trunk road style roads and caution should be exercised when using it for local roads and streets because much of the information is not applicable.

That stated, CD195 has plenty of general application within its pages because the physical space, design speed and user requirements for cycle traffic apply everywhere. It's also an important point that the term "cycle traffic" is being used because we are dealing with a distinct mode of transport which is not motor traffic and it is not walking traffic. As Professor John Parkin says, "cycles are vehicles capable of speed"!

In terms of overall layout, there is a brief initial section for matters which all apply to Highways England, Transport Scotland, the Welsh Government and the Department for Infrastructure. The document then splits into four annexes, one for each for each of the four administrations. 

For England, the national annexe is a set of detailed information for the design of cycling infrastructure on the Highways England network. The annexes for the other three administrations are extremely short with only a couple of clauses each. The key ones are;

NI/1.1 Direction on the design of routes and facilities for cycle traffic in Northern Ireland shall be obtained from the Department of Infrastructure.

S/1.1 The design of routes and facilities for cycle traffic in Scotland shall be in accordance with Cycling by Design.

W/1.1 The design of routes and facilities for cycle traffic in Wales shall be in accordance with Active Travel (Wales) Act 2013 Design Guidance.

So in practice, the bulk of CD195 only applies to the English annexe and the three other administrations use their own guidance which in my view is a problem because of the age of the Scottish and Welsh documents and the absence of anything for Northern Ireland (at least to the best of my knowledge).

In the first part of the UK-wide introduction, we are reminded that the scope of CD195 is for the "design of routes and assets used by cycle traffic" - it's not for shared paths and this is an immediate problem where the default design choice is for shared designs. I'm hoping that in due course there will be better direction in this matter (which will sit elsewhere) because in many cases, there's nothing wrong with sharing if pedestrian traffic is very low and cycle traffic low to moderate.

The photo above is a cycle track on the Danish North Sea island of Fanø. I was the only person walking here and cycle traffic was low. Of course in rural areas there may be walking connections to local services and bus stops for example and in that situation, I'd expect the design to change for a section. For me, this is an issue that needs dealing with, especially as the DMRB standards on sharing are yet to be updated.

The second part of the UK-wide introduction simply refers the reader to other parts of the DMRB which should be read in conjunction with the text. In this case, just one reference to the introduction to DMRB.

So, to the English Annexe, which is set out under the following headings;
  • Foreword
  • Introduction
  • Abbreviations
  • Terms and definitions
  • Types of cycle route
  • Cycle design vehicle
  • Cycle route design
  • Crossings
  • Junctions
  • Signing
  • Normative references
  • Informative references
  • Appendix E/A - One-way and two-way cycle tracks
The introduction repeats the point that the standard is for routes used only by cycle traffic because of higher design speeds (notwithstanding my comments above). The abbreviations and terms/ definitions are helpful to get tuned into the language.

The types of cycle route are a couple of tables. The first looks at the minimum provision for traffic speeds and flows;

The second looks at the five conditions for good cycling infrastructure which will be familiar to students of the Dutch experience;

The cycle design vehicle section recognises that there are many types of cycle and many types of people using them. A "Cycle Design Vehicle" (CDV) of 2.3m in length by 1.2m in width is given to cover most situations;

Frankly, most designers could do with looking that the first two tables and the cycle design vehicle diagram! The point about the CDV is that people need space within which to cycle in terms of forward movement, curves and corners; this idea flows through the annexe.

The section on cycle route design is concerned with the different types of provision given the traffic conditions (lanes, tracks, protection etc) and it recognises that effective widths of provision are eroded by high kerbs, vertical features and gullies. There is advice on visibility, gradients, transitions between types of provision and dealing with bus stops (which should have cycle bypasses). The section contains all of the physical information one could need - a good point is made that two-way cycle tracks should have a centre line to enable people understand that they are two-way.

Because of the CDV and the need to make our infrastructure accessible, we are also treated with this group of clauses which I fully endorse!

E/3.32 Cycle tracks shall be clear of street furniture and obstructions with the exception of features to prevent motor traffic access.

E/3.33 The gap between posts and other physical constraints on cycle tracks shall be a minimum of 1.5 metres to restrict access by motor traffic while retaining access by cycle traffic.

E/3.34 Bollards on cycle tracks shall be aligned in such a way that enables a cycle design vehicle to approach and pass through the bollards in a straight alignment.

E/3.35 A frame and K frame type barriers, often used to prevent motorcycle access, shall not be used on cycle tracks.

Within the section on crossings, there is a large table which sets out the traffic conditions which lead to each type of crossing. For uncontrolled situations, we should not be expecting people to cross multiple traffic lanes. For higher speed roads, the inescapable conclusion is people need either signals to cross or grade separation (the latter where flows and speeds are at the higher end).

One issue I do have an issue with is where cycle tracks are running adjacent to the carriageway or bent-in (from a position away from the road to being adjacent) and the designer is invited to return cycle traffic to carriageway level within a lane before the junction in order to ensure people cycling are in a position which makes them visible.

The document is aimed at trunk road and motorway schemes and so inevitably, this will lead to changes on local roads as part of interface or legacy works. Although this is only for 30mph and lower situations, this type of layout is a cop-out because project sponsors need to work harder to ensure enough land is provided for decent layouts. 

Junctions are treated to detailed advice with emphasis on roundabouts. We're reminded that we should not put cycle lanes on the perimeter of roundabouts because it's dangerous. For compact roundabouts (essentially smaller roundabouts with single lane entries and exits) with more than 8,000 vehicles a day, cycle traffic should be taken around on cycle tracks. I don't think daily traffic flow is a detailed enough metric because in situations with heavy peak flows and very quiet off-peaks, it's still going to be awful to mix with traffic.

The photo above is a standard Dutch compact roundabout with a two-way cycle track, set back crossing points (about 10m), tight vehicle geometry (including HGV overrun around the centre). We can safely copy this approach, yet we don't and nonsense like this layout in Cambridgeshire keeps getting built;

Larger roundabouts (known as normal roundabouts) have a variety of solutions for cycling;
  • provide cycle tracks around the junction, with cycle track crossings of each arm;
  • remodel the junction as a compact roundabout, where permitted by CD 116;
  • provide grade separated cycle tracks around and/or across the junction;
  • introduce signal control to the roundabout, with appropriate cycle track provision;
  • replace the roundabout with a signal controlled junction or another form of junction, with appropriate cycle track provision.
Of course, when crossing each arm, we refer back to the section on crossings and we'll realise that once we have multi-lane approaches/ exits, high speed limits and higher flows we're into signals or grade separation! CD116 is for roundabout design which is a separate blog post in its own right!

The section on signing is mainly about directional signing strategy (so people can follow a decent route to where they are going to) and how the signage should be laid out. After the references, the table on one-way and two-way cycle tracks is useful to explain the advantages and disadvantages of the approaches.

So, there you have it, a blast around the new standard. Frankly, if every designer of trunk road style schemes started using this tomorrow, we'd see a big improvement and actually, there application in suburban areas too. 

The standard is based on an earlier interim advice note which was published in 2016 and so there will be people out there wondering why crap is still being built. It's a two-fold problem. For Highways England schemes, there are various stages where processes are fixed and one of them is on which standards are being used. With many current schemes, the standards fix predates 2016. 

The second issues is one of project scope. While CD195 will be used on new schemes, it's important that issues are brought into project scope in the first place and in my opinion, this also includes matters of historic severance. This is an issue to be tackled away from design standards and will no doubt need political weight brought to bear.


  1. The Cambridge roundabout photo would still meet the guidance if 30mph and <4000 AADT?
    Conversations of "Why not build it nicer?""Guidance says this is fine!""But we can do it better!""Guidance says this is fine......" are a real struggle. A need for more of a push towards "best practice" examples in the guidance?

    Colin Smith

    1. I think you're right in the sentiment of too many designers, but the roundabout is not a proper compact one because of the flare in the lanes out to two on the entries and the exits are fudged. It really is a slog because the document is written by Highways England for themselves and there's no public consultation opportunity.