Recognizing barriers is first step to easing travel burdens

A new study, on which Virginia Tech was a collaborator, provides the clearest picture to date of how profoundly transportation mode shapes access to methadone treatment for opioid use disorder in Connecticut. 

The research, co-authored by College of Natural Resources and Environment Assistant Professor Junghwan Kim, shows that relying on public transit instead of a personal vehicle can multiply travel time by a factor of four or five, creating a major barrier for patients who need daily, in‑person treatment. 

An expert in geospatial modelling and the director of Smart Cities for Good, Kim joined seven scientists and medical doctors from Yale University, and a researcher from Western University in Canada, to compare travel times from all 2,702 census block groups in the state. His advanced geospatial analysis and accessibility modelling builds on an earlier study that looked at the actual time required to reach a treatment center, compared to the perceived time that rarely calculated the burden of travel. 

The results of the study, published in JAMA Network Open, offered a rare, comprehensive car-versus-transit perspective. 

The contrast was dramatic: the median trip to the nearest opioid treatment program (OTP) was just 11 minutes by car, but nearly 42 minutes by public transit. Researchers also found that 53 percent of block groups had either no transit route to an OTP or required more than an hour of travel, effectively cutting off access for residents without a vehicle. 

“This was the second study where I collaborated with the Yale doctors and researchers, so it’s rewarding to know my work will be helping people who might get overlooked,” Kim said. “Importantly, I also brought these research insights back into my classroom, sharing them with my [geographic information system] students to demonstrate how geospatial technologies can be applied to solve real-world problems."

This comparative framework is the study’s central contribution. The new analysis shows that car‑based accessibility dramatically overestimates real-world access for many patients. That gap is especially wide in rural areas, where public transit travel times averaged nearly 57 minutes and 89 percent of communities lacked a workable route, compared with a 19-minute median drive time. 

Kim, a geospatial data scientist in Virginia Tech’s Department of Geography, built the fine‑grained spatial and transit modeling that made this comparison possible. The team divided the state into a grid, with each cell being just under a third of a square mile. Computations determined travel times for both car and transit for each cell before aggregating them to block groups. This high-resolution approach provided a more realistic picture of transportation burdens than traditional county-level or city-level analyses. 

The authors conclude that improving methadone access will require policy changes informed by these transportation inequalities, including expanded transit options, mobile methadone units, and reduced requirements for daily in‑person visits. The study’s comparative, mode‑specific approach—strengthened by Kim’s geospatial analysis—offers policymakers a clearer map of where interventions are most urgently needed. 

Original study: DOI: 10.1001/jamanetworkopen.2025.57361