YR Sports Lab
Highway Lane Radar
If You Never Change Lanes, Which One Is Fastest?
Say you get on the freeway and drive from Taichung to Taipei, locked into a single lane the whole way. Which one jams least: the inside passing lane, the middle lane or the outside lane? This tool estimates the expected trip time for each lane using a Taiwan freeway time-of-day flow model, and tracks traffic density kilometre by kilometre on a live radar.
How do you pick the lane least likely to jam?
Most drivers assume the inside passing lane is always fastest. In reality, the inside lane is quicker on average but far more variable. One slow driver or a minor fender-bender ahead turns the whole passing lane into a car park. The middle lane runs a fraction slower on average but flows far more consistently, and over a full trip with no lane changes it often wins on total time.
How the three lanes differ
Inside (L1, passing lane): average 90–100 km/h, but highly variable. It has the highest chance of short stoppages from crashes or slow vehicles, and that variability propagates, so a single choke point often affects several kilometres in a row.
Middle (L2): average 85–92 km/h with the lowest variability. Little interference from on- and off-ramps and less exposure to passing-lane incidents, which makes it the most stable choice if you plan to lock into one lane.
Outside (L3): average 70–80 km/h. Constant interference from ramp traffic and a high share of trucks give it the lowest overall speed, with moderate variability.
For every lane in every segment, the radar runs the following calculation:
- Assign a base speed factor from the current time slot (weekday or weekend, peak or off-peak)
- Apply each lane's characteristic parameters (mean speed and variability)
- Scatter 1–2 congestion hotspots into each stretch to simulate crashes or ramp backups
- Sum the time required for every kilometre along the route to get the ETA for staying in that one lane
- Pick the lane with the shortest total time as the recommendation
The perfect case study: the Hsuehshan Tunnel
Why the Hsuehshan Tunnel is the most extreme "one lane all the way" case
The Hsuehshan Tunnel runs 12.942 km, making it the longest road tunnel in Taiwan and the fourth longest in Asia, and lane changes are banned along its entire length. In other words, the tool's core assumption of locking into one lane is not a tactical choice inside the tunnel, it is the law. Once you enter the portal, the lane you picked is your fate for the next 13 kilometres.
Inside (car-only lane): 90 km/h speed limit, closed to heavy vehicles. Average speed of 80–90 km/h with the lowest variability, the most stable option overall.
Outside (bus and truck lane): a high share of coaches and trucks, average speed around 70–80 km/h. The longer following distances trucks keep drag the whole outside lane down.
Switch the ROUTE selector above to Hsuehshan Tunnel to enter tunnel mode: yellow ceiling lights, double solid white lines and a warm glow make the "no turning back once you are in" feeling immediate.
Data sources and limitations
Data and model sources:
- Real-data layer: MOTC TDX Transport Data eXchange, live freeway VD speeds from the Freeway Bureau (refreshed roughly every 25 minutes; if TDX is unreachable the tool falls back to the simulation model below and keeps running)
- Lane texture: the relative speed and variability of the inside, middle and outside lanes come from published Freeway Bureau lane-utilisation statistics
- City-to-city distances: based on Google Maps freeway routing (roughly ±5% error)
- Supported routes: Freeway 1 (Sun Yat-sen), Freeway 3 (Formosa), Freeway 5 (Chiang Wei-shui, Taipei to Su-ao) and the Hsuehshan Tunnel (part of Freeway 5, lane changes prohibited)
The "Semi-live traffic | last updated hh:mm" line on the panel shows the timestamp of the current TDX data. If it reads "Simulation mode", TDX is temporarily unreachable and the tool has fallen back to the time-of-day model.