Motorcycle taxis' varying degrees of complementarity and substitution with public transit in Bangkok

Motorcycle taxis are widely used in Bangkok, Thailand and across the Global South due to wide availability, low investment costs to owners, and low fares for passengers. Our study using Bangkok as a case study investigates the role of motorcycle taxis in relationship to public transit, determining if the role of motorcycle taxis could vary across different areas instead of being solely either complementary or substitute. Recent studies on motorcycle taxis have taken an overly broad approach that covers large geographical areas. Most provided a definite one-or-the-other answer, concluding that motorcycle taxis either complement or substitute for public transit. By contrast, our research shows evidence of their adaptive role when looking at smaller areas, where the roles of motorcycle taxis vis-à-vis rail and bus transit change according to locational and spatial characteristics. We use the number of registered motorcycle taxi drivers as a proxy for supply in 180 subdistricts of Bangkok, which were classified into three groups: central business district (CBD) subdistrict, inner suburban subdistrict, and outer suburban subdistrict. Using spatial autoregressive model (SAR) modeling, we found that in outer suburban subdistricts, for every additional transit station, there are 177 more motorcycle taxi drivers. Yet in CBD subdistricts, motorcycle taxi is lowest complementary to rail transit and for every additional bus stop in a CBD subdistrict, there are 10 more motorcycle taxi drivers. This suggests the degree of complementarity between motorcycle taxis and public transit varies with different locational and spatial contexts and transit types. With the findings of adaptive roles of motorcycle taxis depending on land use, transit availability, and activity patterns in each area, policymakers should consider appropriate policies and regulations based on these roles in relation to public transport.