Bicycle transportation engineering is the study of transportation engineering as it affects bicycles and cycling. It includes the design of dedicated transport facilities for cyclists, but also the study of how mixed-mode environments (i.e. where cyclists are not segregated from other traffic) can be made to work safely.
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Various methods of altering or reallocating the roadway right-of-way to facilitate bicycling and create bikeways have been added to many of the manuals used by transport planners and engineers.
A shared use path is a bikeway that is physically separated from motorized vehicle traffic by an open space (generally landscaping) or some form of barrier.[1]
A cycle track, also called a separated cycle lane, is a bicycle exclusive facility that provide physical separation from motorized vehicle traffic within the road right-of-way, generally by means of kerbs or other barriers.[2] Cycle tracks can either incorporate bicycle-only signal phases at intersections (for 100% separation) or utilize “mixing zones” to merge bicycle and motor vehicle traffic. A cycle track combines the user experience of a separated path with the on-road infrastructure of a bike lane.
A designated bicycle lane, according to the 1998 United States Manual on Uniform Traffic Control Devices, is:
Cycle lanes require less space compared with the option of providing side paths or separate tracks, and generally do not have the legal / priority issues that facilities separated from the general traffic may have (depending on the locally applicable road laws). However, if traffic is heavy or fast, the lack of physical separation from motor vehicles may make cycle lanes unattractive to less confident cyclists. The lack of separation also means they are more apt to be blocked by (illegally) parked vehicles.
A hard shoulder, or simply shoulder, is a reserved area outside of a roadway, but within the road right-of-way. In addition to (a) serving as a buffer area in the event of a temporary loss of vehicle control, (b) providing emergency access for ambulances and police cars and (c) providing a space for inoperable vehicles, it may also be used by pedestrians and bicyclists.
Wide outside through lanes help motorists pass slower cyclists without having to decrease speed or change lanes.[3] This method is held by some to be particularly important on roads with a high proportion of wide vehicles, such as buses or heavy trucks. These lanes also provide more room for cyclists to filter past queues of other vehicles in congested conditions. The use of such lanes is specifically endorsed by Cycling: the way ahead for towns and cities, the European Commission policy document on cycle promotion.[4]
Cycle friendly infrastructure argues for a marked lane width of 4.25 m (14 ft).[5] It is argued that, on undivided roads, this width provides cyclists with adequate clearance from passing wide vehicles while being sufficiently narrow to deter motorists from attempting to “double up” and form two lanes. This “doubling up” effect may be related to junctions. At non-junction locations, greater width might be preferable if this effect can be avoided.
A shared bus lane is a bus lane that allows cyclists to use it. Depending on the width of the lane, the speeds and number of buses, and other local factors, the safety and popularity of this arrangement vary.
Guidance produced for Cycling England endorses bus lanes as providing cyclists with a direct and barrier free route into town centres and as avoiding the difficulties associated with other provisions such as shared-use footways.[6] According to a French survey 42% of cyclists described themselves as "enthusiasts" for shared bus bike lanes versus 33% who were of mixed opinion and 27% who were opposed.[7] Many cycling activists view these as being more attractive than cycle paths, while others object to being in close proximity to bus exhausts.[7] The sharing of bus lanes has been described as "generally very popular" with cyclists in London.[8]
As of 2003, mixed bus/cycle lanes accounted for 118 km of the 260 km of cycling facilities in Paris. [9] The French city of Bordeaux has 40 km of shared bus cycle lanes.[10] It is reported that that in the city of Bristol, a showcase bus priority corridor, where road space was re-allocated along a 14 km stretch also resulted in more space for cyclists and had the effect of increasing cycling.[11] The reverse effect has also been suggested, a review carried out in London reports that cycling levels fell across Kew bridge following the removal of a bus lane - this was despite a general increase in cycling level in the city generally.[12] In addition, it is arguably easier, politically speaking, to argue for funding of joint facilities rather than the additional expense of both segregated cycling facilities and bus-only lanes.[13] [14]
In some instances. bus lane proposals have run into vehement opposition from cycling representatives - a typical theme is the perceived generation of conflict due to the narrowing of other lanes already shared by cars/cyclists so as to create space for the bus lanes[15] The TRL reports that cyclists and bus drivers tend to have low opinions of each other[8] There have been reports in Dublin of conflict as cyclists choose to cycle in the bus lanes and a bus driver apparently expected them to use adjacent cycle tracks instead.[16] In some other cities the arrangements seem to work successfully, with bus companies and cyclists' groups taking active steps to ensure that understanding is improved between the two groups of road users.[14][17][18]
Shared space schemes, which are characterized by the removal of road markings, signs and signals, give all street users equal priority and equal responsibility for each others safety. Experiences where these schemes are in use, show that street users, particularly motorists, undirected by signs, curbs or road markings, reduce their speed and establish eye contact with other users. Results from the thousands of such implementations worldwide all show casualty reductions and most also show reduced journey times.[19] Following the partial conversion of London's Kensington High Street to shared space, accidents were reduced there by 44% (the London average was 17%).[19]
A bicycle boulevard is a low speed street which has been designed to discourage cut-through motor vehicle traffic and to give priority to cyclists as through-going traffic.
Bike paths are bicycle routes that follow an independent right-of-way. There are two distinct types of bike paths: those used exclusively by bicycles and those shared with pedestrians. In the United States almost all bike paths are shared with pedestrians.
Bike paths are often built on old railroad right-of-ways (called rail trails) and as part of greenways and foreshoreways.
How traffic signals are designed and implemented directly impacts cyclists.[20] For instance, poorly adjusted vehicle detector systems, used to trigger signal changes, may not correctly detect cyclists. Traffic managers in Copenhagen link cyclist-specific traffic signals on a major arterial bike lane to provide green waves for rush hour cycle-traffic.[21] Cycling-specific measures that can be applied at traffic signals include the use of advanced stop lines and/or bypasses.
The frequency with which lights change is important to cyclists who may conserve energy by anticipating green lights ahead i.e. the shorter the interval the better for cyclists. Intersection clearance times and green wave timing may also be relevant.
Bicycle tires being narrow, road surface is more important than for other transport, for both comfort and safety. The type and placement of storm drains, manholes, surface markings, and the general road surface quality should all be taken into account by a bicycle transportation engineer. Drain grates, for example, must not catch wheels.
Bicycle parking is another important part of Bicycle Transportation Engineering. In most of the United States, bicycle parking facilities are scarce, or are so inadequate that nearby trees or parking meters are used. The hitching post type of bicycle stand is an improvement over the old type that had a slot for the front wheel but only allow for two bicycles per post. The Netherlands, where bicycles are much in use, has two-tiered bicycle racks giving high density (the handlebars overlap) and security (the bicycle is held well and is easy to lock).
Secure bicycle parking is argued to be a key factor influencing the decision to cycle.[22] To be considered secure, the parking must be of a suitable design: allowing the bicycle to be locked via the frame (see bicycle stand). A readily observable location can also permit so-called passive security from passers-by. Weather protection is also desirable. As a rule, where cycling is encouraged as an alternative to motoring, efforts are made to make bicycle parking more convenient and attractive to use than nearby car parking arrangements. This usually means providing a wide distribution of visible, clearly designated parking spots, close to the entrances of destinations being served.
Storage rooms or bicycle lockers may also be provided. In some cases large concentrations of bike parking may be more appropriate, sometimes being supervised and sometimes charging a fee. Examples include large bike parking facilities at public transport interchanges such as railway, subway, tram, bus stations, or at bike stations[23] where they may be useful in Mixed-mode commuting.
Conversely, where cycling is seen as an unwelcome or inappropriate activity, or due to lack of knowledge about best practices, bicycle parking may simply not be provided or else placed at awkward, distant, and out-of-sight locations.[24] Cyclists may be expressly forbidden from parking their bicycles at the most convenient locations. In April 2007, the authorities at the University of California's Santa Barbara campus started confiscating bicycles not parked at the allegedly inconvenient official bike racks.[25] Often, property owners display signage on fencing to discourage bicyclists from locking their bicycles.
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