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Mobility Monitoring – Roadways – Arterial Roadways
OVERVIEW • REGIONAL TRENDS • ROADWAYS • INTERSECTIONS • TRANSIT
BICYCLE/PEDESTRIAN • HOV LANES • TRANSPORTATION DEMAND MANAGEMENT • PARK-AND-RIDE
Overview • Arterial Roadways • Crashes • Freeways • Performance Measures • Traffic Volumes
Average Speed
Overall, about 9 percent of the monitored Class III arterial roadway miles in the region have average travel speeds of 18 mph or less in the morning peak period. This number increases to 12 percent in the evening peak period. About one-half of these slow-travel miles are on the monitored roadways located in the Inner Core subregion, which comprises Boston and its inner suburbs.

Traffic on 13 percent of Class I/II (major arterial) roadways experiences average travel speeds of 27 mph or less during the morning peak period, worsening to nearly 18 percent during the evening peak period.

The difference in travel speeds between roadways in the Boston-and-inner-suburbs subregion and roadways in the outer-suburbs is strongly apparent. In the morning peak period, 20 percent of the monitored arterial roadways in the Boston-and-inner-suburbs subregion have average travel speeds of 18 mph or less, compared to 5 percent in the outer suburban subregions.

In the evening peak period, 28 percent of the monitored arterial roadways in the Inner Core subregion have average travel speeds of 18 mph or less, compared to 8 percent in the outer-suburbs subregion. Furthermore, only a quarter of the arterial roadways in the Inner Core subregion have average speeds above 30 mph in the evening, compared to nearly 70 percent for the roadways in the outer-suburbs.
Speed Index
Regionwide, about 16 percent of the monitored Class III arterial roadways have average observed speeds in the morning peak period that are less than 70 percent of the speed limit; in the evening peak period, this figure is 19 percent. In terms of average observed speeds near or above the posted speed limit, 62 percent of the roadways in the morning peak period were observed in this range; in the evening, this number drops to 55 percent. Of the CMP-monitored roadways in the Boston and inner suburbs subregion, slightly less than a third had observed average speeds in the evening peak period near or above the posted speed limit.

The Class III roadways in Boston and its inner suburbs show a significant difference in the speed index between the morning and evening peak periods: 31 percent of roadways in the morning have average observed speeds that are less than 70 percent of the speed limit, as compared to about 40 percent of roadways in evening period.

For Class I/II arterial roadways, comparing the speed index between the morning and the evening peak periods shows a different congestion picture. Twenty-one percent of these major arterials with partially limited access have average observed speeds that are less than 70 percent of the posted speed limit in the evening peak period compared to nearly 25 percent in the morning peak period.
Delay
Observed delay is greater in the evening peak period than in the morning peak period. During the morning peak period, there are 42 intersections on the CMP roadway network with average approach delays higher than 80 seconds per vehicle; in the evening peak period, 78 intersections on the CMP network have approaches with average delays higher than 80 seconds per vehicle, nearly twice that of the morning peak period. In the evening peak period, 15 percent of the signalized intersections on the CMP roadway network have approaches that experience 55 seconds or more of delay; 6 percent of the signalized intersections experience 80 seconds or more of delay. Most of the high-delay intersections are located in the Boston-and-inner-suburbs subregion.
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