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TABLE 3 Recommended calibration parameters J for signalized streets
SI Units
Facility Type Signals Per Km Free-Flow Speed (km/h) Speed at Capacity (km/h) J
Arterial Class I 0.333 80 53 2.21E-05
Arterial Class I 1.000 80 31 2.04E-04
Arterial Class I 2.500 80 15 1.25E-03
Arterial Class II 0.500 64 40 4.99E-05
Arterial Class II 1.000 64 28 2.00E-04
Arterial Class II 2.000 64 18 7.91E-04
Arterial Class III 2.000 56 17 8.02E-04
Arterial Class III 3.000 56 13 1.78E-03
Arterial Class III 4.000 56 10 3.18E-03
Arterial Class IV 4.000 48 10 3.17E-03
Arterial Class IV 5.000 48 8 4.99E-03
Arterial Class IV 6.000 48 7 7.11E-03
USER'S GUIDE
Customary Units
Facility Type Signals Per Mile Free-Flow Speed (mph) Speed at Capacity (mph) J
Arterial Class I 1 50 33.1 2.21E-05
Arterial Class I 2 50 19.3 2.04E-04
Arterial Class I 4 50 9.6 1.25E-03
Arterial Class II 1 40 24.8 4.99E-05
Arterial Class II 2 40 17.8 2.00E-04
Arterial Class II 3 40 11.2 7.91E-04
Arterial Class III 3 35 10.9 8.02E-04
Arterial Class III 5 35 7.9 1.78E-03
Arterial Class III 6 35 6.3 3.18E-03
Arterial Class IV 6 30 6.1 3.17E-03
Arterial Class IV 8 30 5.0 4.99E-03
Arterial Class IV 10 30 4.3 7.11E-03
procedures contained in the 2000 HCM. These two tables use posted speed limit and signal density criteria shown in
the following HCM definitions of facility types: Table 4.
· Freeway--A multilane, divided highway with a min-
imum of two lanes for the exclusive use of traffic in 3.4 SIGNAL DATA REQUIRED
each direction and full control of access without traf- BY HCM/AKCELIK
fic interruption.
· Multilane highway--A highway with at least two lanes The zero-flow control delay and the between-signal delay
in each direction for the exclusive use of traffic, with no are required to estimate speeds for signalized arterial streets.
control or partial control of access, but that may have The zero-flow control delay (Do) is computed as follows:
periodic interruptions to flow at signalized intersections
( )
no closer than 2 miles apart. N C 2
· Two-lane highway--A highway with only one lane in D0 = DF 1 - g C Equation 8
3,600 2
each direction (with or without occasional passing lanes)
for the exclusive use of traffic, with no control or partial Where:
control of access, but that may have periodic interrup-
tions to flow at signalized intersections no closer than D0 = the zero-flow control delay at the signal (hours);
2 miles apart. N = maximum of one, or the number of signals on the
· Arterial--A signalized street that primarily serves segment;
through traffic and that secondarily provides access to 3,600 = conversion from seconds to hours;
abutting properties, with signals spaced 2 miles or less g/C = average effective green time per cycle for signals
apart. Arterials are divided into classes according to the on segment;
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TABLE 4 HCM arterial class criteria
Arterial Class SI Units Customary Units
Posted Speed Limit Signal Density Posted Speed Limit Signal Density
Class I 70-90 km/h 0.3-2.5 signals/km 45-55 mph 0.5-4 signals/mi.
Class II 55-70 0.3-3.1 35-45 0.5-5
Class III 50-55 2.5-6.3 30-35 4-10
Class IV 40-50 2.5-12.5 25-35 4-20
Source: Chapter 15, Urban Streets, HCM.
Note: There may be instances of overlaps in arterial class definitions. The analyst should consult Chapter 15 of the HCM for
additional information on the identification of a specific arterial class.
C = average cycle length for all signals on the segment default value of 120 seconds can be used. A survey of local
USER'S GUIDE
(seconds); and average signal cycle lengths by area type (e.g., downtown,
DF = delay factor, suburban, and rural) may be desirable to establish appropri-
= 0.9 for uncoordinated traffic-actuated signals, ate local default values.
= 1.0 for uncoordinated fixed-time signals, The segment delay between signals (DL) is estimated as
= 1.2 for coordinated signals with unfavorable follows:
progression,
= 0.9 for coordinated signals with favorable pro-
dL
gression, and DL = L Equation 9
= 0.6 for coordinated signals with highly favorable 60
progression.
Where:
If the ratio of green time per cycle for the arterial through
movement is not known, a default value of 0.44 can be used. L = the length of the segment and
Similarly, if the signal cycle length is not known, then a dL = the delay per mile, given in Table 5.
TABLE 5 Segment delay between signals
secs/mile
Arterial Class: I I I II II II III III IV IV
Free-Flow Speed (mph) 55 50 45 45 40 35 35 30 35 30
signal spacing (miles)
0.05 107
0.10 42 35 62 60
0.15 32 21 37 30
0.20 29 25 22 25 14 27 20
0.25 32 28 24 24 20 16 17 7 19 12
0.30 27 23 19 19 12 7
0.40 17 14 14 14 6 2
0.50 8 6 8 8 3 0
1.00 0 0 0 0 0 0
secs/km
Arterial Class: I I I II II II III III IV IV
Free-Flow Speed (km/h) 88 80 72 72 64 56 56 48 56 48
signal spacing (km)
0.08 n/a n/a n/a n/a n/a n/a n/a n/a n/a 66.9
0.16 n/a n/a n/a n/a n/a n/a 26.3 21.9 38.8 37.5
0.24 n/a n/a n/a n/a n/a n/a 20.1 13.1 23.2 18.8
0.32 n/a n/a n/a 18.1 15.6 13.8 15.7 8.8 17.0 12.5
0.40 19.7 17.5 15.0 15.0 12.5 10.1 10.7 4.4 12.0 7.5
0.48 16.6 14.4 11.9 11.9 7.5 4.5 n/a n/a n/a n/a
0.64 10.3 8.8 8.8 8.8 3.8 1.3 n/a n/a n/a n/a
0.80 4.7 3.8 5.0 5.0 1.9 0.0 n/a n/a n/a n/a
1.60 0.0 0.0 0.0 0.0 0.0 0.0 n/a n/a n/a n/a
Source: 2000 HCM, Exhibit 15-3, Segment Running Time Per Mile. Table computed by subtracting running time if traveling at free-flow speed from
running time shown in exhibit.
