BOSTON · LINE REPORT · RANK 1 OF 5
Mattapan Line93 out of 100.
Steady.
Ashmont to Mattapan. Measured across 7,474 trips and 56,246 stop observations from Aug 20, 2026 through Sep 18, 2026.
93/100Steady
BALANCED ARRIVALS89.6%within 0.5–1.5× scheduled headway
LONG GAPS6.9%above 1.5× scheduled headway
BUNCHING3.5%below 0.5× scheduled headway
ON-PACE SEGMENTS99.7%no more than 2 minutes slow
DAILY METER
Thirty service days
The latest seven-day score declined by 1.7 points compared with the first seven days.
Aug 20, 2026Sep 18, 2026
READING THE LINE
What the score captures
On Mattapan Line, the median observed interval between comparable arrivals was 10.1 minutes. The median measured segment ran 23 seconds under schedule.
The daily score can move because headways spread out, trains bunch together, or station-to-station travel slows. It does not assign a cause without supporting incident, construction or weather evidence.
Audit the complete formula →LATEST DAY · Sep 18, 2026
95daily score
92.8%balanced arrivals
5.4%long gaps
99.9%on-pace segments
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