Table 1 Properties of transport features that determine barrier effects

Physical

Static

Motorways and feeder roads, railways, waterways

Fences, railings, noise screens, height differences (embankment, ditches), road width, traffic isles, visual conditions at crossing points [22]

Dynamic

Transversal, across a feature (car or tram traffic)

Traffic flow, traffic direction, speed, proportion of heavy vehicles, parked vehicles [8], bunching of vehicles [57], waiting time at controlled crossings [87], snow clearing

Longitudinal, along a feature (car or tram traffic)

Traffic flow, speed, proportion of heavy vehicles, parked vehicles [67], affecting mostly bicycles [48, 67, 87]

Psychological

Characteristics of transport features and their environment that have a deterring effect without creating a physical barrier

Conditions for fear of accidents

Experienced risk of traffic accidents occurring when crossing or travelling along a transport feature [70, 78]

Conditions for fear of crime

Lighting, visibility, escape opportunities, social surveillance [6, 142]

Conditions for discomfort

Noise, pollution [60, 92], dust [30], smell, vibrations, splashes, less attractive routes [40], amount of scrap on and around crossing facilities [88]

Formal

Traffic rules

Traffic lights, possibility for manually controlled traffic lights, one-way streets [87], parental rule that a child is not allowed to cross a road [87, 130]

Planned infrastructure projects

Reserves in land use planning documents can create zones that form a barrier for transport [31, 43], uncertainty about the possible barrier effects of planned infrastructure can impact land prices and urban development [127]