Saga Prefecture high-speed rail map. Dedicated HSR lines and upgraded corridors by speed category: 200–250 km/h, 250–300 km/h and 300+ km/h.
Saga Prefecture high-speed rail network: purpose-built high-speed lines and upgraded conventional corridors capable of 200 km/h or above, filterable by speed category. Purpose-built HSR lines use moving-block signalling allowing trains every 3–4 minutes at full speed, with no level crossings and no mixed freight traffic. Upgraded corridors are cheaper to build but share capacity with slower services, limiting both frequency and top speed. The map shows where dedicated high-speed infrastructure ends and upgraded conventional rail begins — the key distinction for understanding real-world journey times.