Measured day · heading home
Cape Cod traffic on Sunday, September 13
117 readings on the day, compared against 12 other measured Sundays (10,593 readings in all). Every figure below is measured — nothing is modelled or estimated.
Collection is still running for this day — these are the readings so far, and the figures will keep moving until the travel window closes. The day is frozen into a permanent record once it ends.
How this Sunday compares
Each grey line is one measured Sunday. Sunday, September 13 is drawn over them, so the question isn’t what the delay was but where it sat among the Sundays we’ve actually recorded.
| Hour | Sunday, September 13 | Typical Sunday | Range across Sundays |
|---|---|---|---|
| 8 AM | 0 min | 0 min | 0–0 min (n=7) |
| 9 AM | 1 min | 2 min | 0–5 min (n=7) |
| 10 AM | 16 min | 16.5 min | 3–26 min (n=8) |
“Typical” is the median across the other measured Sundays, shown only for hours at least three of them recorded. Not a percentile — with 13 sundays the honest summary is the observed range.
Which routes drove it, at 10 AM
Delay in minutes, and what that is as a share of the route’s clear-road time. The share matters: a long drive collects more absolute minutes without being more congested.
| From | Sagamore Bridge | Bourne Bridge | Hyannis |
|---|---|---|---|
| Boston | 15 min +24% | 9 min +13% | 34 min +41% |
| Providence | 3 min +5% | 1 min +2% | 17 min +20% |
| New York City | 64 min +26% | 61 min +25% | 76 min +28% |
| Hartford | 28 min +21% | 26 min +20% | 37 min +24% |
| Worcester | 4 min +4% | 2 min +2% | 20 min +18% |
| Plymouth | 2 min +7% | 1 min +3% | 12 min +24% |
By share of a clear run, the worst route at 10 AM was Boston → Hyannis — 34 minutes on a 82-minute drive (+41%). New York City → Hyannis lost more raw minutes (76), but on a 268-minute drive that is a smaller share — which is why ranking by minutes alone mostly ranks routes by length.
Methodology
Drive times are collected every 15 minutes during Cape Cod travel windows via the Google Routes API, measured to the mainland approach of each bridge so the figure isolates the crossing rather than on-Cape traffic. Delay is the with-traffic time minus that route’s free-flow baseline; readings more than 3× free-flow are excluded as routing outliers.
Comparisons use only the 18 routes sampled at every capture. Origins sampled hourly are shown on the day’s own figures but kept out of cross-day comparison, because a route measured four times an hour and one measured once would otherwise appear to differ for reasons that are about sampling rather than traffic. The network median is the median across those routes of each route’s hourly median — taken across routes, not across readings, so a heavily-sampled route can’t pull the number toward itself.
Days are frozen from the raw readings once finished, so these figures stay citable after the raw rows age out of retention. Raw readings (CSV) · CC BY 4.0 — cite “Cape Cod Traffic (cape-cod-traffic.com)”.
Driving home this Sunday?
On Sunday, September 13 the 10 AM–11 AM window was the one to avoid. Live readings tell you whether this Sunday is tracking the same way.