The problem of narrow "bike lanes" : the case of "shared parking lanes".

Cyclists require an operational space of minimum width 1000mm with 300-500mm or more clearance on both sides, depending on the circumstances. This is a design fundamental. Often facilities appear to be, or might be assumed to be, safe yet they do not meet these minimum "operational" requirements. The "BIKE LANE" in fig 1 is an example from Brisbane (Australia) where there is inadequate space, thus creating a real risk for unsuspecting or novice cyclists, especially if a car door is opened suddenly. Should this occur, the cyclist may react by turning away, or be deflected away, in both cases, into and in front of fast moving vehicular traffic.

Fig 1: BIKE LANE with inadequate space for cyclists

The "problem" with narrow "bike lanes" is therefore that they potentially convey a false sense of safety. However, the "problem" also includes regulatory obligations eg a cyclist leaving the "bike lane" is changing lanes and therefore must not change lanes unless safe to do so. That is, the "bike lane" creates a legal obligation and responsibility on the cyclist leaving the "bike lane", irrespective of the circumstances. This is not only important in the case of avoiding car doors or walk-out pedestrians or indeed debris on the "bike lane", it is also important if attempting to turn right when leaving the "bike lane". A further "problem" is the motorists expectation that cyclists will in fact stay, and are expected to stay, in the "bike lane" thus creating a potentially false sense of a reduced need for motorists to be concerned about the cyclists. As one of a number of trials of various infrastructural facilities for cyclists in Brisbane (Australia), a section of "shared parking" "bike lane" was constructed to the minimum operational requirements. The following photographs illustrate the major operational dimensions. The width provided for car parking should be minimised, however, the space should also allow for some latitude. As can be seen in Fig 2, there is adequate space for the cyclist. In Figs 2 and 3, the marked car bay is 2100 wide while the tape measure is set at 2000.

Fig 2 shows car bay widths and cyclist

Fig 3 shows detail of car bay widths

The space between the car and the edge line (and adjacent traffic) should be maximised. In this case, the total width from kerb face to edge line is in excess of 4000 while the tape measure is set at 3500.

Fig 4 shows total "bike lane" width

The next photo (Fig 5) shows the same situation but with the car door on "hold open" which is not fully open. As can be clearly seen in this photo, there is adequate space for the cyclist with clearances from both the car door and the edge line in this example but not with the 3500 width.

Fig 5 shows car door at the "hold open" position


The next photo (Fig 6) shows a more distant view. In Fig 7, the photo includes the standard nominal width 1100 BIKE symbol indicating that this is a "bike lane". As this BIKE symbol is also the same width as the operational space for a cyclist, it can be seen how the 3500 measurement would result in the BIKE symbol being located adjacent to the car bay with the majority of the BIKE symbol covered by the swept path of the opened car door and little if any clearance to adjoining traffic.

Fig 6 shows a more distant view including a standard 1100 wide BIKE symbol

The use of a 3500 wide shared parking lane raises extremely serious issues in regard to compromising the safety of cyclists given that a "bike lane" implies safe space on the road. This is especially the case where it might be assumed the facility is "safe". This situation is further compromised if the adjoining lane widths are also minimal width. As can be seen in the final photo (Fig 7), while the space provided in this trial looks to be quite large and perhaps even excessive, in fact, this is the appropriate width to maintain the operational clearances. In this photo, the tape measure is set at 4000 for comparison with the location of the BIKE symbol marking the "bike lane".

Fig 7 shows the actual space required for "safe" cycling in a "shared parking lane".

In this trial of the required space on a typical urban road in Brisbane, it is clear that rather than compromise the safety of cyclists, the compromise was to remove parking on one side of the road in order to provide an adequate (but arguably minimum width) "bike lane" on both sides of the road while maintaining adequate traffic lanes on a 60km/h arterial road. Arguably, "safe" facilities should always be provided where, as in this case and in general in urban areas, a diversity of cyclist types and competencies is to be expected. In other trials in Brisbane where parking has been considered necessary on both sides of the road, the more recent use of the yellow BIKE symbol to indicate how to "share the road" provides a better compromise than a "narrow bike lane" in that it allows the operational space for the cyclists (represented in each case by the location and width of the 1100 nominal width of the BIKE symbol) to be located further from the cars. Because the yellow BIKE symbol is not enclosed by an edge line, cyclists are not required (or expected) to travel within their "lane" but rather may choose to "share the road", and therefore are treated as any other vehicle because bicycles are "vehicles" under the road regulations. For further information on the use of the yellow BIKE symbols, there are three items under BURG at Transport Resource Page

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Tuesday, 4 May 2004 Back