LCDS - Chapter 4, Junctions and Crossings

The Embassy will be discussing the draft London Cycling Design Standards this evening on Twitter - (hashtag #LCDSHour). We've already posted some thoughts on Chapters 1 and 2, and Chapter 3. In anticipation of this evening I'm going to give some initial thoughts on Chapter 4 on Junctions and Crossings.

As with Chapter 3, on Cycle Lanes and Tracks, the good details on junctions that are contained here are lost in a long chapter that contains a lot of sub-par infrastructure. And also - as with Chapter 3 - an objective, statistics-based approach to what kind of treatment is appropriate (according to motor traffic volume and speed) is absent, replaced by a subjective approach that uses words like 'high' and 'low' without defining what they mean.

For instance, the chapter recommends removing priority markings on page 146 - 

In some cases no road markings may be considered to be necessary where vehicle speeds and flows are low’

Well, how low? The Dutch have clear guidance on when this kind of treatment - which employs a 'priority to the right' approach, without road markings, is appropriate. But 'low' is too vague. 'Normal roundabouts' are similarly described as suitable for cycling in 'low flow' conditions (4.5.4) - but again, how low is low?

Likewise, 'shared' toucan crossings are mentioned on p.137, before the chapter states that ‘high demand’ should merit a ‘parallel crossing’ (i.e. separation of pedestrian and cycle movements). But what is 'high demand'? It's not quantified. This is worrying, because it opens the door to compromised infrastructure.

Figure 4.8 on p.148 has some useful detail on what lane widths are acceptable (at refuge islands) but instead of a clear PCU-based approach, giving motor traffic volume, the headings in the table are instead worded 'traffic calmed' and 'no traffic calming', which is not at all clear.

There's also a reliance, on the one hand, on 'bodges' of a pedestrian kind, and inadequate infrastructure suitable for dealing with movements at busier junctions, on the other.

At the low end, a straightforward zebra is described as a 'cycle crossing' in Figure 46 on p.137, which really isn't acceptable - a zebra crossing is for pedestrians. Zebra crossings, in addition to shared use pavements, are described as a 'pragmatic choice' on p.141, but should this kind of provision be endorsed, at all? And on p.144 -

consideration could be given to allowing cycle left and right

turns by diverting cyclists onto shared areas of footway and parallel or toucan crossings

Left turns should be achieved with cycle-specific infrastructure, not by pushing pedestrians and cyclists into conflict with shared use footway.

At the other extreme, there is far too much information on Advanced Stop Lines - a full eight pages of various forms and types. This is a form of provision that the chapter itself admits allows comfortable right turns 'only if the cyclist arrives during a red phase' - i.e. infrastructure that only functions on a part-time basis, at best. ASLs really aren't adequate, and should only be employed in genuinely low-traffic environments, if at all. 'Head-start' signals - given a mention here - do not address the fundamental problems with ASLs.

It is also disappointing to see the 'always stop' form of signalising cycling movements (as employed at Bow Roundabout) being endorsed, described here as a 'cycle gate'. Paragraphs 4.4.21-24 contain the phrase 'two stop lines for cyclists’, which is telling - really, this is a bodge used to retain motor traffic capacity, at the expense of convenience for people cycling, and it flies in the face of the points made in this same chapter about signalling for cycling needing to be 'equitable' and 'convenient'.

Section 4.4.34 talks of 'support for right turns', making the good point that these need be achievable in a comfortable way. But it has a strange way of presenting the case for a two-stage right turn -

When faced with a difficult right turn, many cyclists choose to make the turn in two stages on carriageway.

Surely the word ‘choose’ here should be replaced with the words ‘are forced’? Nobody chooses to add inconvenience to their journey, and there are signs here that the 'two-stage' right turn is really being endorsed as an easy compromise, rather than being developed properly for the convenience and comfort of people cycling.

While there is some tentative discussion of using Dutch signalised junction design, incorporating 'protecting islands', and good detail on separately signalling left turn motor vehicle movements from cycling, there isn't anything at all on the potential for 'simultaneous green' signalling for bicycle traffic, which would remove conflict with motor traffic at signalised junctions completely. 

Nor is there wholehearted endorsement of the concept of removing left-turning bicycle traffic (or bicycle traffic progressing straight ahead on a T-junction) from signal control; it is only stated that this may be appropriate 'in some instances', when really this should be a default to aim for in all circumstances. 

There is nothing - at all - on cycle track treatments at priority junctions, which is really quite alarming - the only diagram of a continuous footway across the junction mouth is marked up with a cycle lane (p.153). Meanwhile there is an over-reliance on painted markings at major junctions - for instance annular painted cycle lanes around the perimeter of roundabouts (really quite bad design) get a mention, as does the concept of  

continuing the ahead cycle lane past the left-turn slip lane [which] will require left-turning vehicles to cross the cycling facility

Slip lanes and painted cycle lanes really shouldn't be mixed at all; paths will be crossed at shallow angles, and that's not a good idea, at all.

The chapter is a little weak on roundabouts generally, but this is unfortunately mainly a function of the fact that good design (proven elsewhere!) is still being trialled, and awaiting approval - and a historical failure in Britain to design properly for cycling at larger roundabouts. It is interesting to see this chapter recommending against the use of mini-roundabouts anywhere on a cycling route, raising good points about how poor they are for comfort, particularly with obtuse junction angles.

Low-level signals - recently given trial approval by the DfT- appear to be being endorsed here as a stand-alone signal, without any accompanying full-size high level signal heads. This is a mistake. Low-level signals are simply an extra bit of convenience; they should always complement full-size high-level signals, particularly as low-level signals are very difficult to see from a distance. There are safety and convenience reasons for always marrying the two.

Finally, it is pleasing to see this chapter stating that ‘gyratory removal should not be an end in itself’, arguing that

The focus of any gyratory redesign should be on enabling more direct journeys with less delay, particularly for pedestrians and cyclists, and on allowing more ‘conventional’ approaches to be taken to cycling provision and to management of motor traffic speed and volume. This may only entail part-removal or partial remodelling of a gyratory or one-way system.