Ever notice that a lot of people seem to be driving faster than the speed limit?
It might surprise you to learn that if speed limits were based on traffic engineering standards, as required by federal law, this would never happen. Most drivers choose safe speeds on their own, so the engineering standard is to set a speed limit near the 85th percentile speed of free flowing traffic. That means the violation rate should be 15% or less. A majority of speeding cars is proof that the speed limit is too low.
This table compares 85th percentile speeds to actual speed limits at a number of locations in the Boston area.
“Limit” means the current speed limit. * means the posted limit is not legal.
“50th” means the 50th percentile (median) speed.
“85th” means the 85th percentile speed.
“%” means percent of drivers voluntarily obeying the speed limit (i.e. not following behind a slower car).
Roads are grouped by agency in control.
Massachusetts SPEEDS AND SPEED LIMITS
Metropolitan District Commission
Road
City
Location
Limit
50th
85th
%
Charles River Road
Watertown
E. of Watertown Square
30
39
44
1
Greenough Blvd.
Watertown
N. of Arsenal Street
40
45
50
17
S. of Arsenal Street
30
38
44
5
Hammond Pond Parkway
Newton
S. of Beacon Street
30
44
50
0
Brookline
S. of Route 9
40
45
50
22
VFW Parkway
Boston
St. Josephs Cemetary
35
41
45
8
Brookline
South Street
35
40
46
20
Boston
E. of West Roxbury Parkway
35
42
48
9
Centre Streeet
Boston
Westchester Road
30
38
43
4
Jamaicaway
Boston
Parkwood Terrace
25
36
39
0
West Roxbury Parkway
Boston
Bellevue Hill Road
40
42
46
36
Storrow Drive
Boston
EB at Clarendon Street
40
52
59
0
WB at Clarendon Street
40
49
57
9
BU Bridge
40
53
59
1
Soldiers Field Road
Boston
Western Ave. Bridge
40
50
56
4
W. of Eliot Bridge
35
42
49
11
EB E. of Beacon Street
30
42
46
4
WB E. of Beacon Street
35
46
52
3
Nonantum Road
Boston
W. of N. Beacon Street
40
45
49
19
Memorial Drive
Cambridge
EB E. of Mass. Ave.
35
42
48
12
WB E. of Mass. Ave.
35
39
42
22
BU Bridge
35
42
47
9
Fresh Pond Parkway
Cambridge
Fresh Pond Lane
30
36
40
6
Longfellow Bridge
Cambridge
Memorial Drive ramp
30
40
47
6
Turnpike Authority
Road
City
Location
Limit
50th
85th
%
Turnpike extension
Boston
Mass. Ave.
55
61
67
20
Market Street
55
67
73
4
Newton
Walnut Street
55
65
71
5
Woodland Street
55
63
69
11
Turnpike
Weston
Winter Street
65
69
75
23
Westborough
Spring Road
65
71
78
19
Oxford
Merriam Road
65
71
77
22
Warren
Little Bemis Road
65
71
77
16
Stockbridge
Route 102
65
71
77
15
MassHighway
Road
City
Location
Limit
50th
85th
%
Route 1
Newbury
S. of Hanover
55
52
57
80
Danvers
Peabody C.L.
50
50
58
50
Plainville
S. of 152
55
49
56
85
Route 2
Belmont
Route 60
55
66
71
5
Lexington
W. of Pleasant St.
55
67
74
4
Lincoln
Page Road
45
55
62
6
Concord
Sandy Pond Road
45
55
61
6
Acton
W. of 27
55
64
72
11
Lancaster
Exit 36
55
65
71
11
Templeton
Otter River Road
55
65
72
3
Phillipston
Highland Ave.
55
59
63
26
Route 2A
Lexington
Emerson Gardens Road
35
37
42
34
Lexington
Tufts Road
30
38
42
2
Lincoln
Bedford Lane
40
44
49
17
Route 3
Bedford
Old Billerica Road
55
66
73
2
Weymouth
Middle Street
60
64
68
36
Norwell
River Street
60
66
72
19
Route 6
Yarmouth
West Yarmouth Road
55
65
73
3
Route 7
Sheffield
S. of Great Barrington T.L.
55
52
57
83
Wiliamstown
S. of Route 2
45
45
50
53
Route 8
Sandisfield
S. of 57
55
57
63
41
Route 9
Newton
Parker Street
50
50
55
50
Wellesley
Emerson Road
50
54
60
29
Williamsburg
Post Office
25
33
37
3
Williamsburg
E. of South Street
25
34
39
4
Windsor
E. of 8A
55
58
63
35
Route 10
Bernardston
E. of I-91
55
53
58
61
Route 20
Watertown
Emerson Road
35
37
41
38
Waltham
Summit Avenue
35
37
42
32
Weston
Crescent Street
40
41
44
49
Weston
Linwood Avenue
45
44
47
72
Brimfield
2.8 mi. W. of Sturbridge
55
57
64
40
Lenox
S of 7A
55
55
62
51
Route 24
Berkley
Bryant Street
65
71
77
20
Route 28
Milton
Ridgewood Street
45
50
56
24
Quincy
Skyline Trail
50
47
53
71
Route 88
Westport
S. of Old County Rd.
55
58
67
32
I-91
West Springfield
N. of Route 5
65
67
73
46
Northampton
S. of Route 5&10
65
67
73
46
I-93
Milton
Exit 3
55
68
76
4
Milton
Pleasant Street
55
61
67
24
Medford
Exit 33 (NB)
55
66
72
13
Medford
Exit 33 (SB)
55
71
77
4
Wilmington
N. of Route 62
65
69
77
31
I-95
Boxford
near Route 133
65
72
78
18
Route 112
Goshen
S. of Ashfield T.L.
55
58
64
37
Route 125
Andover
S. of 28
50
54
59
21
Route 128
Gloucester
S. of Concord St.
55
62
69
24
Waltham
Route 117
55
67
73
6
Needham
Kendrick Street
55
66
71
5
Needham
N. of Great Plain Ave.
55
65
73
7
Route 135
Wellesley
Bacon Street
45
48
53
31
Route 138
Milton
Canton T.L.
40
41
46
46
Route 146
Millbury
Route 122A
50
61
68
5
I-195
Mattapoisett
W. of North St.
65
68
76
36
Fall River
Route 24
55
62
69
22
I-290
Worcester
East Central St.
50
57
64
14
I-495
Bolton
N. of 62
65
68
74
36
Amesbury
S. of I-95
65
69
75
26
Cities and towns
Road
City
Location
Limit
50th
85th
%
Route 126
Bellingham
Fox Run Road
35*
42
45
8
Commonwealth Avenue
Brighton
W. of Harvard Street
30*
36
41
16
Evergreen Cemetery
30*
37
42
9
Jewish War Veterans Drive
Dorchester
Franklin Park
25*
37
41
2
Washington Street
West Roxbury
Cowing Street
25*
40
47
0
Middlesex Turnpike
Burlington
Terrace Hall Ave.
35
41
46
14
Dover Road
Dover
Main St.
30*
39
43
2
Route 109
Millis
Dover Road
40*
45
50
17
Spring Street
Lexington
Underwood Ave.
30*
37
41
3
Greendale Avenue
Needham
Highgate Street
40
42
46
35
Auburn Street
Newton
W. of Washington Street
25
34
38
1
Chestnut Street
Newton
Kodaya Road
25*
34
38
4
Lexington Street
Newton
N. of Auburndale Ave.
30
36
40
8
Commonwealth Avenue
Newton
E. of 128
35
38
42
14
E. of 16
35
41
45
9
E. of Walnut
35
36
40
48
Washington Street
Newton
E. of 30
35
37
41
27
W. of 30
35
36
41
39
Route 181
Palmer
South High Street
40
40
44
51
Route 16
Watertown
Derby Road
30*
32
37
28
Walnut Street
30*
34
38
20
Route 30
Weston
Ware Street
45
42
46
81
Speeds on the Turnpike, MDC parkways, city and town roads, and some state highways in the Boston area were measured with a LIDAR speed measuring device in 2000 and 2001 and in 2005. Speeds for other state highways were measured by MassHighway loop sensors in 1999 and are totals for a complete day instead of just free-flowing traffic. Traffic speeds are usually very similar in both directions. When speeds in both directions are available and differ significantly, both are listed separately. Otherwise the average is listed.
What does this mean?
The national standard is to round the 85th percentile up to the next multiple of 5 MPH to determine a speed limit. None of the roads measured meets that standard. Only a few are within 5 MPH. All but one of these are minor state highways where engineers have been permitted to have some influence in the process of setting speed limits.
The MDC doesn’t do engineering studies, and it shows. Typical speed limits are 15 MPH too low. Both Hammond Pond Parkway and Storrow Drive have speed limits 20 MPH too low.
Speed limits on major highways are set by politicians. Compliance is around 5% in 55 MPH zones (which were mostly posted 60 until 1974) and up to 25% in 65 MPH zones. Based on these measurements, speed limits should be increased from 55 and 65 to 70, 75, and 80.
*The speed limit in Franklin Park, Boston is illegal because it has not been approved by the state. The Mayor, who was almost hit by a car, insists on strict enforcement of the illegal speed limit. The limit should be 40, not 25. Commonwealth Avenue is also illegally posted.
*Middlesex Turnpike in Burlington was rebuilt a few years ago, widened to four lanes plus left turn lanes at intersections. The 35 MPH speed limit for the old road has been posted on the new road.
*Dover Road, Dover is illegally posted 30. The town Police Chief has admitted the signs are illegal:
*Spring Street, Lexington is illegally posted 30. The authorized limit is 35; 31% of drivers obey that limit.
*Route 16, Watertown, is illegally posted 30. No speed limit is authorized; the proper speed limit would be 35.
*Gardner St in Hingham is illegally posted: Channel 4 did a story here
Many other speed limits were only 5 MPH too low when they were set, but now they are much too low. Cities and towns don’t like to change speed limits, and some limits have remained unchanged since the early 1950s!
