U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
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| Publication Number: FHWA-HRT-14-020 Date: January 2015 |
Publication Number: FHWA-HRT-14-020 Date: January 2015 |
Speeds were also compared for heavy trucks and passenger vehicles to determine whether speed changes between the two vehicle types were different. Sites in Oregon and Washington had a significant number of logging and other heavy trucks. Data were aggregated by passenger vehicle and heavy trucks for five sites.
The traffic counters used to collect data can classify vehicles according to FHWA's 13 vehicle types. Vehicle types 1, 2, and 3 were included as passenger vehicles, and vehicle types 4 through 13 were considered to be heavy vehicles (referred to as heavy trucks). Data were evaluated for the before period and 12-month after period for the five sites. The 12-month after period was used because the signs would have been place at that point for some time and any novelty effect would have worn off. Data for each period were disaggregated by vehicle type. Data were evaluated for both the PC and CC for each site.
The tables in this appendix show the actual change in the fraction of vehicles traveling 5, 10, 15, or 20 mph or more over the posted or advisory speed rather than showing percent change as was done in the main section of the report.
Table 135 shows results for Washington SR 7. At the PC, little change was observed for the heavy trucks, while passenger vehicles had a moderate change with a decrease in mean speed of 2 mph and a decrease in 85th percentile speed of 3 mph. At the CC, both the passenger vehicles and trucks had increases in speed, but trucks had an increase that was twice that of passenger vehicles (increase of 3 mph in mean compared with an increase of 6 mph for heavy trucks with an increase in 85th percentile speeds of 2 and 4 mph).
Table 136 show results for Washington US 101. Passenger vehicles had a decrease in mean speed of almost 5 mph while the mean speed for heavy trucks decreased by 6.5 mph. However, the 85th percentile speed decreased by the same amount for passenger vehicles and heavy trucks (6 mph). At the CC, mean and 85th percentile decreases were similar.
Speed changes for Oregon OR 238 are shown in Table 137 and were similar for passenger vehicles and heavy trucks at both the PC and CC. Decreases in mean and 85th percentile were 2 to 3 mph at the PC and 0 to 1 mph at the CC. Decreases in the number of vehicles exceeding the posted speed limit were greater for heavy trucks at the PC, and increases were greater for passenger vehicles at the CC.
Table 138 shows results for Oregon US 101. Changes were also similar for both the PC and CC, with 1- to 2-mph decreases at the PC and 5- to 7-mph decreases at the CC. Heavy trucks had a greater decrease in the fraction of vehicles exceeding the advisory speed by 5, 10, 15, or 20 mph for the PC and CC.
Table 139 shows speed metrics were similar for passenger vehicles and heavy trucks at the PC for Oregon OR 42 with reductions in average speed and 85th percentile speeds of 2 mph. Decreases in the fraction of vehicles exceeding the advisory speed were also similar for passenger vehicles and heavy trucks. At the CC, a decrease of 7 mph for the average and 85th percentile speeds resulted for the passenger vehicles, while trucks had decreases of 4 to 8 mph.
Table 135. Speed changes for Washington SR 7 PC by heavy truck versus passenger vehicle.
|
Point of Curvature |
Center of Curve |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Passenger Vehicle |
Heavy Truck |
Passenger Vehicle |
Heavy Truck |
|||||||||
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
|
Mean speed |
43.5 |
41.4 |
-2.1 |
40.6 |
41.5 |
0.9 |
38.7 |
42.1 |
3.4 |
35.7 |
41.7 |
6 |
85th percentile speed |
50 |
47 |
-3 |
47 |
47 |
0 |
47 |
49 |
2 |
44 |
48 |
4 |
Percent vehicles exceeding posted or advisory speed limit |
||||||||||||
By 5 mph |
74.6% |
58.8% |
-15.8% |
58.7% |
61.8% |
3.2% |
57.3% |
58.2% |
0.9% |
40.2% |
61.3% |
21.1% |
By 10 mph |
46.9% |
26.8% |
-20.1% |
33.2% |
27.5% |
-5.7% |
27.8% |
28.0% |
0.3% |
13.6% |
28.9% |
15.3% |
By 15 mph |
16.5% |
8.9% |
-7.7% |
5.8% |
8.4% |
2.6% |
6.4% |
14.4% |
8.0% |
1.0% |
10.2% |
9.2% |
By 20 mph |
2.8% |
1.5% |
-1.3% |
0.5% |
0.8% |
0.3% |
0.9% |
6.1% |
5.2% |
0.0% |
3.2% |
3.2% |
Table 136. Speed changes for Washington US 101 PC by heavy truck versus passenger vehicle.
|
Point of Curvature |
Center of Curve |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Passenger Vehicle |
Heavy Truck |
Passenger Vehicle |
Heavy Truck |
|||||||||
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
|
Mean speed |
48.6 |
43.8 |
-4.8 |
48.1 |
41.6 |
-6.5 |
38.9 |
36.9 |
-2.0 |
37.8 |
35.2 |
-2.6 |
85th percentile speed |
55 |
49 |
-6 |
53 |
47 |
-6 |
43 |
41 |
-2 |
41 |
41 |
0 |
Percent vehicles exceeding posted or advisory speed limit |
||||||||||||
By 5 mph |
97.9% |
95.0% |
-2.9% |
99.1% |
86.6% |
-12.5% |
85.8% |
72.3% |
-13.5% |
84.6% |
61.2% |
-23.5% |
By 10 mph |
94.4% |
81.8% |
-12.6% |
94.9% |
68.9% |
-26.1% |
43.3% |
27.3% |
-16.0% |
29.7% |
17.9% |
-11.8% |
By 15 mph |
78.8% |
46.1% |
-32.6% |
77.3% |
34.4% |
-42.9% |
10.4% |
4.6% |
-5.9% |
2.4% |
2.1% |
-0.2% |
By 20 mph |
46.4% |
13.5% |
-32.9% |
37.5% |
6.8% |
-30.7% |
1.8% |
0.5% |
-1.3% |
0.3% |
0.4% |
0.1% |
Table 137. Speed changes for Oregon OR 238 PC by heavy truck versus passenger vehicle.
|
Point of Curvature |
Center of Curve |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Passenger Vehicle |
Heavy Truck |
Passenger Vehicle |
Heavy Truck |
|||||||||
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
|
Mean speed |
41.8 |
39.1 |
-2.7 |
40.4 |
37.4 |
-3 |
36.9 |
36.5 |
-0.4 |
35.9 |
35.4 |
-0.5 |
85th percentile speed |
46 |
44 |
-2 |
45 |
42 |
-3 |
41 |
40 |
-1 |
39 |
39 |
0 |
Percent vehicles exceeding posted or advisory speed limit |
||||||||||||
By 5 mph |
95.3% |
85.0% |
-10.4% |
90.5% |
71.1% |
-19.4% |
74.1% |
69.3% |
-4.8% |
64.3% |
61.6% |
-2.7% |
By 10 mph |
72.0% |
47.5% |
-24.5% |
63.8% |
34.2% |
-29.5% |
24.1% |
21.6% |
-2.5% |
13.4% |
11.9% |
-1.4% |
By 15 mph |
25.9% |
10.5% |
-15.4% |
16.1% |
6.4% |
-9.7% |
2.9% |
2.3% |
-0.6% |
0.6% |
1.9% |
1.3% |
By 20 mph |
3.3% |
0.8% |
-2.5% |
0.3% |
0.0% |
-0.3% |
0.1% |
0.1% |
0.0% |
0.3% |
0.3% |
0.0% |
Table 138. Speed changes for Oregon US 101 PC by heavy truck versus passenger vehicle.
|
Point of Curvature |
Center of Curve |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Passenger Vehicle |
Heavy Truck |
Passenger Vehicle |
Heavy Truck |
|||||||||
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
|
Mean speed |
55.9 |
54.3 |
-1.6 |
53.9 |
51.7 |
-2.2 |
55.0 |
49.6 |
-5.4 |
53.9 |
47.0 |
-6.9 |
85th percentile speed |
61 |
60 |
-1 |
60 |
58 |
-2 |
61 |
55 |
-6 |
60 |
53 |
-7 |
Percent vehicles exceeding posted or advisory speed limit |
||||||||||||
By 5 mph |
89.5% |
81.9% |
-7.6% |
80.3% |
64.2% |
-16.2% |
86.1% |
52.5% |
-33.6% |
80.1% |
36.8% |
-43.3% |
By 10 mph |
67.1% |
51.1% |
-16.0% |
51.7% |
32.6% |
-19.1% |
55.0% |
19.1% |
-36.0% |
49.0% |
9.3% |
-39.7% |
By 15 mph |
27.0% |
17.8% |
-9.2% |
19.4% |
11.1% |
-8.4% |
20.5% |
3.0% |
-17.5% |
15.5% |
1.4% |
-14.0% |
By 20 mph |
4.4% |
3.0% |
-1.4% |
4.1% |
2.9% |
-1.2% |
3.2% |
0.3% |
-2.9% |
2.3% |
0.0% |
-2.3% |
Table 139. Speed changes for Oregon OR 42 PC by heavy truck versus passenger vehicle.
|
Point of Curvature |
Center of Curvature |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Passenger Vehicle |
Heavy Truck |
Passenger Vehicle |
Heavy Truck |
||||||||||
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
Before |
12 mo |
Change |
||
Mean speed |
43.5 |
41.2 |
-2.3 |
42.4 |
40.2 |
-2.2 |
53.1 |
46.1 |
-7 |
49.8 |
45 |
-4.8 |
|
85th percentile speed |
48 |
46 |
-2 |
47 |
45 |
-2 |
59 |
52 |
-7 |
55 |
51 |
-4 |
|
Percent vehicles exceeding posted or advisory speed limit |
|||||||||||||
by 5 mph |
79.4% |
62.8% |
-16.5% |
70.7% |
56.1% |
-14.6% |
97.7% |
85.9% |
-11.8% |
96.3% |
83.9% |
-12.4% |
|
by 10 mph |
42.0% |
24.9% |
-17.1% |
34.2% |
18.3% |
-15.9% |
91.2% |
63.5% |
-27.7% |
82.1% |
54.7% |
-27.3% |
|
by 15 mph |
11.1% |
5.2% |
-5.9% |
6.6% |
3.0% |
-3.6% |
76.2% |
28.6% |
-47.6% |
52.5% |
21.0% |
-31.5% |
|
by 20 mph |
1.5% |
1.3% |
-0.2% |
0.5% |
0.6% |
0.1% |
43.2% |
7.9% |
-35.2% |
20.3% |
4.1% |
-16.2% |
|
