Approved Corrections to HCM 2000 Jul 2005

8/6/2019 Approved Corrections to HCM 2000 Jul 2005

1/19

Updated 7/8/2005

Previous update 2/27/2004

Page 1 of 7

Approved Corrections and Changes for the

Highway Capacity Manual 2000

TRB Committee AHB40, Highway Capacity and Quality of Service

Unless stated otherwise, corrections apply to both the U.S. Customary and Metric versions.

NEW PAGE ITEM CORRECTION

APPROVAL

DATE

Chapter 6 Update variable symbol and definition according to changes

made in Equation 20-16.

10/13/2004

7-3 Last sentence on

page

Change the last sentence to read The space mean speed is

38.3 mi/h, calculated as (60)[3 (2.0 + 1.5 + 1.2)].1/13/2003

7-6 4th

paragraph Change first sentence to read "The slope of any ray line

drawn from the origin of the speed-flow curve represents the

inverse ofdensity, based "

6/29/2002

8-2 PedestrianCharacteristics

Change the third sentence to read An average walking speedof4.0-ft/s is appropriate.

1/13/2003

8-12 Exhibit 8-12 Change Facility descriptions for Detroit, MI to be I-96

Jeffries Freeway at Warren and Lodge at W. Grand Blvd.

1/13/2003

10-10 Exhibit 10-7 Correct service volumes (see attached tables). 6/29/2002

10-11 Exhibit 10-8 Delete middle yellow interval and associated dotted line to

reflect a standard green-yellow-red phasing sequence (see

attached revised exhibit)

7/26/2003

10-24 Correct chapter

reference

Change the third sentence following Exhibit 10-19 to read:

Chapter 16 provides

1/12/2004

10-36 Reference 6 Add at the end, 1982, specifically citing Mekky, A., On

Estimating Turning Flows at Road Junctions, Traffic

Engineering and Control Journal, Vol. 20:10, October 1979,pp. 486-487.

1/13/2003

10-45,

10-46

Equations A10-1

and A10-3,

Exhibit A10-9

Correct equations A10-1 and A10-3 and associated text and

Exhibit A10-9 for the Quick Estimation Method for

Signalized Intersections in Appendix A (see attached

material)

1/13/2003

12-15 Replace Exhibit

127b

Replace with Figure 7, NCHRP Project 20-7 (160). (See

attached material.)

10/13/2004

13-18 1st

paragraph Revise first sentence to read "Procedures in Chapter 24

generally apply to weaving segments between 500 to 2,500 ft

long." For the metric version, "segments between 150 to

750 m long."

6/29/2002

15-2 Exhibit 15-1 Revise first item in Input box to read Define segments 6/29/200215-8 Equation 15-6 Replace with Equations 15-6a and 15-6b and redefine terms

(see attached material). For the U.S. Customary version of

the manual, substitute English units for the metric units

shown.

6/29/2002

15-16 Example Prob. 1 In the table under Step 1, column two, change PF = 0.0 to PF

= 1.0.

6/29/2002

15-19 Example Prob. 2,

Worksheet

Revise worksheet numbers, metric version (see revised

material)

6/29/2002


2/19

Updated 7/8/2005


Page 2 of 7


APPROVAL

DATE

15-20 Correct appendix

reference

Change the fourth checked sentence under The Factsto read:

Segment lengthsdescribed in Appendix B,

1/12/2004

15-22,

15-23

Example Prob. 4,

solution steps and

worksheet

Revise value in Step 4 for k = 0.4. Revise calculated values

based on this change in other steps and worksheet on next

page (see revised material).

6/29/2002

15-24,

15-25

Example Prob. 5,

solution steps

Revise formula in Step 3 for d. Revise value in Step 4 for

k = 0.4. Revise subsequent values in other steps based on

these changes (see revised material).

6/29/2002

15-25 Appendix A Revise step 3 under LOS analysis to be:

3. Convert the hourly directional volumes to through-movement 15-min flow rates by subtracting the turn

movement volumes served by exclusive turn-lane lane

groups and then divide this difference by the PHF.

6/29/2002

15-25,

15-26

Appendix A Revise the second set of seven steps under the planning

analysis procedures (see revised material)

6/29/2002

15-27 Appendix B Redefine steps 2, 4, and 5:

2. Determine the appropriate FFS for each street segment.

4. Make test-car travel time runs over each street segmentduring the

5. Total travel speed for the entire urban street sectionshould also

6/29/2002

16-19,

16-152

Equation 16-10,

Equation G16-8

Apply the following constraints for the delay and queuing

progression factor formulas:

(i) PF 1.0 and PF2 1.0 for Arrival Types 1 and 2(ii) PF 1.0 and PF2 1.0 for Arrival Types 4 to 6(iii) P 0.95 (Rp 0.95/u) for both PF and PF2(iv) Rp 0.95/yL for both PF and PF2(v) PF2 = 1.0 for yL u (XL 1.0)(vi) Rp(1 0.95*(1 u)/yL)/u for both PF and PF2, and(vii) Rp = 1.0 (P = u), therefore, PF = 1.0 and PF2 = 1.0 for

yL 0.95(viii) If conditions (iii), (iv) and (vi) create inconsistent

constraints on Rp and P, set Rp = 1.0 and P = u,

therefore, PF = 1.0 and PF2 = 1.0

May 2001

16-39 Box 19 Change v/c to v/s Feb. 2004

16-47 Capacity

worksheet

Add flow ratios to WB direction = 0.313

And to NB direction = 0.289

Feb. 2004

16-50 Box 24 Change v/c to v/s Feb. 2004

16-61 Example Prob. 2,

Supplemental

Worksheet for

Ped/Bike Effects

on Permitted Left

and Right Turns

The EB left effective pedestrian green time should be 23.4

seconds. The subsequent calculations for the EB left will

change slightly, with no change in the final ped-bike left turn

adjustment factor. The WB right is already shown as 23.4

seconds, thus no change is required.

7/28/2001


3/19

Updated 7/8/2005


Page 3 of 7


APPROVAL

DATE

16-73 Capacity

worksheet

Add flow ratios:

NBpro = 0.084

NBper =0.000

SBper = 0.418SBThRt = 0.322

EBper = 0.237

EBThRt = 0.170

WBThRt = 0.233.

16-144 Correct Equation

F16-3 (both

versions)

The last part of Equation F16-3 should read:

[ ])X,1min(1Q

cT1u...

b

=

1/12/2004

16-151,

16-152

Equations G16-2

through G16-5

Replace NLG in the denominator of each equation with

(fLU*NLG)

1/14/2002

16-153 Equation G16-9 All places where (XL1) appears should be replaced with

(XL1) + QbL/(cL*T). All places where kBXL appears shouldbe replaced with kBX. The results should be expressed in its

simplest form.

1/14/2002

16-153 Terms under

Equation G16-9

Define kB as "second-term incremental factor" 1/14/2002

17-7 1st paragraph and

sidebar

Change the third sentence in top paragraph to read "Base

values of tc and tfare shown for two- and four-lane major

streets. Due to limitations in the available data, this

procedure is not applicable to intersections with six-lane

major streets."

Delete the sidebar - "Base values for a six-lane major street

are assumed to be the same as those for a four-lane majorstreet." and replace with "This procedure is not applicable to

intersections with six-lane major streets."

7/28/2001,

6/29/2002

17-15 Equations 17-18,

17-19 and

surrounding text

The time to discharge the vehicles that arrive during the

red is given by Equation 17-18.

gq1 =v C (1 P)

s(17-18)

where v is either vT or vL,prot.

The time to discharge the vehicles that arrive on thegreen and join the back of the queue is given by equation 17-

19.

gq2 =v C P gq1

s geff v C P(17-19)

where v is either vT or vL,prot.

6/29/2002


4/19

Updated 7/8/2005


Page 4 of 7


APPROVAL

DATE

17-16 Exhibit 17-12 Replace with two figures (see attached figures). 6/29/2002

17-16 Redefining f f = the proportion of through and protected left turn traffic

which departs the upstream signalized intersection and

subsequently arrives at the subject two-way stop-

controlled intersection with respect to the through andprotected left turn traffic departing the upstream

signalized intersection. If there are no opportunities for

vehicles to leave the roadway between the upstream

signalized intersection and the TWSC intersection, then

f is equal to 1.

6/29/2002

17-16 Add Equation 17-

21b and text

The downstream flow after a period equal to the green time

after the platoon reaches the unsignalized intersection is vc,g

and is given by:

qgg

pmax,cpg,c )F1)(fvRv(fvRv

+=

Again, v is either vT or vL,prot

6/29/2002

17-17 Equation 17-22 Replace with the multi-part equation and following text (see

attached material).

6/29/2002

17-19 Equation 17-28 The equation 17-28 should read

>

=

otherwise

pvvifp

pvv

vxcxc

x

xcxc

xuc

0

)1(5.1)1(5.1

min,,

min,,

,,

Remove the definition s under equation 17-28 and add

vc,min = as defined on page 17-17

6/29/2002,

modified

7/26/2003


5/19

Updated 7/8/2005


Page 5 of 7


APPROVAL

DATE

17-19 New Equation

17-28aBelow equation 17-28 and the references to thevariables in the equation, insert the following:

The user can provide values of the proportion of

unblocked time for a particular unsignalized intersectionmovement caused by upstream signals, the px values.

Similarly the flow in the blocked period can also be

given as vblock in veh/h. The appropriate conflicting

flow for the unblocked period is given by Equation 17-

28a.

>

=

otherwise

pvvifp

pvv

v xblockxcx

xblockxc

xuc

0

)1(

)1(

,

,

,,

(see attached material)

7/26/2003

17-21 Flared Minor-Street Approaches

Modify procedure (see attached material) 6/29/2002

17-36 4th

paragraph, 2nd

sentence

The volume on the subject approach is increased

incrementally until the degree of utilization on any one

approach exceeds 1.0.

1/12/2004

17-53,

17-61,

17-62,17-71,

App. A

Correct Worksheet

5a and 5b

Correct Worksheet 5a and 5b by changing the left column

heading under Movement 2 and Movement 5 to VT

instead ofVT,prog.

1/12/2004

18-24 Correct Example

Problem 3, Step 4

The top equation in step 4 should read:vtot = 48 + 27 + 40 + 21 + 20 = 156 p/cycle

1/12/2004

18-25 Correct Example

Problem 3, Step 5

The last equation in step 5 should read:

s1.170.16

14*7.2

0.4

0.462.3t =

++=

1/12/2004

20-1 Revise text Paragraph to be added after the first paragraph under the

section titled - Limitations of the Methodology

" The operational analysis methodologies in this chapter are

not intended to address capacity and traffic flow on two-lane

highways in developed areas. Typically, two-lane highway

segments in these areas (for example, a two-lane highway

through a small town) are subject to lower speed limits and

have few to no passing zones. In addition, the effects of

operations at signalized and/or unsignalized intersections,

which may be significant, are not accounted for in the current

methodology."

10/13/2004


6/19

Updated 7/8/2005


Page 6 of 7


APPROVAL

DATE

20-3 Correct sentence Change the second sentence, sentence paragraph, under

LEVELS OF SERVICE to read: Exhibit 20-2 reflects the

boundary maximum values of percent

1/12/2004

20-10 Equation 20-7 To reduce the potential for misunderstanding, HCM Equation

(207) should be rewritten using the exp function, as shownbelow, rather than as e raised to a power:

BPTSF = 100 (1 exp (0.000879vp))

10/13/2004

20-20 Replace Equation

2016

Replace with Equation 7, NCHRP Project 20-7 (160). (See

attached material.)

10/13/2004

20-22 Equation 20-17 To reduce the potential for misunderstanding, HCM Equation

(2017) should be rewritten using the exp function, as shown

below, rather than as e raised to a power:

BPTSFd = 100 (1 exp (avdb))

10/13/2004


2020

Replace with Table 10, NCHRP Project 20-7 (160). (See

attached material.)

10/13/2004


2021

Replace with Table 9, NCHRP Project 20-7 (160). (See

attached material.)

10/13/2004

20-39 to

20-41

Update Example

Problem 3

According to changes in Exhibit 20-20 and 20-21, and

Equation 20-16.

10/13/2004

20-41 Correct exhibit

references

In the fourth box under Average Travel Speed, change the

references to (Exhibit 20-7 or 20-13)

1/12/2004

20-42 Correct equation

in Step 2

Change the coefficient to 2 as the multiplier for 1.7 in the

denominator (numerator not shown) of the ATSpl calculation

as follows:

11.11

)7.1(2

11.1

13.21

++

++

7/24/2004

20-42 to20-43

Update ExampleProblem 4

According to changes in Exhibit 20-20 and 20-21, andEquation 20-16.

10/13/2004

22-19,

22-46

Correct box

numbering

In the hexagonal box titled Adjust HCM capacities? delete

the number 5 reference to a step.

1/12/2004

22-56 Correct term inequation A22-3

Revise the last term in the equation to read:

OFRD (i1,p)

10/13/2004

23-5 Exhibit 23-3 Correct Exhibit 23-3 figure to comply with Exhibit 23-2

values [no curves going beyond max flow rate of 2400

pc/h/ln nor dropping below 50mph; LOS A density line

angled to the left to intersect the 55mph curve at 600 pc/h/ln]

(see revised figure)

6/29/2002

24-8 Exhibit 24-7 Correct the Nw equation for Type C configuration: the

middle term should be 0.00011L and not 0.00011.6/29/2002

25-3 2nd

paragraph Revise first bullet to read "Maximum total flow approaching

a merge or diverge area on the freeway (vF)"

6/29/2002

25-6 Exhibit 25-5 Correct Equation 2 under 6-lane freeways: the third term

should be 0.003296SFR and not 0.003296.6/29/2002

25-17 Equation 25-12 Change the units in the definition for vFto (pc/h) from(pc/h/ln)

6/29/2002


7/19

Updated 7/8/2005


Page 7 of 7


APPROVAL

DATE

27-10 Top paragraph Revise last sentence of top paragraph to read, For certain

special conditions, users should multiply the base values by

1.2 (12) for heavy two-way flow (25-50% of passengers

moving in the opposite direction) through a single doorchannel, and by 0.9 (16) for a low-floor bus. For primarily

single-direction flow through either double-stream doors or

two single-stream doors, the exhibit reduces the base values

for a single door channel by a factor of 0.6 (14,15).

1/13/2003

27-38 Correct chapter

reference

In the first checked sentence under Comments change the

last reference to (from Chapter 16);

1/12/2004

30-6 to

30-8

Equations 30-5,

30-6, 30-7, 30-8,

Exhibit 30-4

Correct equations and exhibit under section titled

Determining Link Speed (see attached material)

6/29/2002

30-35 Correct EquationA30-15 (both

versions)

Correct Equation A30-15 by adding brackets as shown:

++++=

TvX8)1x()1X(T900

vX36005D

2

2

1/12/2004

31-31 Add a reference Add an additional reference after number 1:

1a. Elefteriadou, L., G. List, J. Leonard, H. Lieu, M.

Thomas, R. Giguere, R. Brewish, G. Johnson. Beyond

the Highway Capacity Manual: A Framework for

Selecting Simulation Models in Traffic Operational

Analyses. In Transportation Research Record 1678,

TRB, National Research Council, Washington, D.C.,

1999, pp. 96106.

10/13/2004


8/19

Highw ay Ca pa c ity Manua l 2000

Chapter 10 - Urban Street Concepts 10-10Signalized Intersections

RECOMMENDED CHANGES FOR ERRATA (US CUSTOMARY)

EXHIBIT 10-7. EXAMPLE SERVICE VOLUMES FOR URBAN STREETS

(SEE FOOTNOTES FOR ASSUMED VALUES)This table containsapproximate values. It is

meant for illustrativepurposes only. The valuesare highly dependent onthe assumptions used. Itshould not be used foroperational analyses orfinal design. This tablewas derived usingassumed values listed inthe footnote.

Service Volumes (veh/h)

Lanes A B C D EClass I

1 N/ A 850 920 1010 1130

2 N/ A 1710 1850 2020 2280

3 N/ A 2570 2770 3050 3420

4 N/ A 3440 3700 4060 4560

Class II

1 N/ A N/ A 670 840 880

2 N/ A N/ A 1470 1690 1770

3 N/ A N/ A 2280 2540 2660

4 N/ A N/ A 3090 3390 3550

Class III

1 N/ A N/ A 480 780 8402 N/ A N/ A 1020 1600 1680

3 N/ A N/ A 1560 2410 2530

4 N/ A N/ A 2130 3220 3380

Class IV

1 N/ A N/ A N/ A 780 800

2 N/ A N/ A N/ A 1570 1620

3 N/ A N/ A N/ A 2370 2430

4 N/ A N/ A N/ A 3160 3250

NotesN/A - not achievable given assumptions below.This table was derived from the conditions listed in the following table.

Class

I II III IVSignal density (sig/mi) 0.8 3 5 10Free-flow speed (mi/h) 50 4 0 3 5 30Cycle length (s) 110 9 0 8 0 70Effective green ratio 0.45 0.45 0.45 0.45Adj. sat. flow rate 1850 1800 1750 1700Arrival type 3 4 4 5Unit extension (s) 3 3 3 3Initial queue 0 0 0 0Other delay 0 0 0 0Peak-hour factor 0.92 0.92 0.92 0.92% lefts, % rights 10 1 0 1 0 10Left-turn bay Yes Yes Yes YesLane utilization factor According to Exhibit 10-23, Default Lane Utilization

Factors


9/19

Highw ay Ca pa c ity Manua l 2000

Chapter 10 - Urban Street Concepts 10-10Signalized Intersections

RECOMMENDED CHANGES FOR ERRATA (METRIC)

EXHIBIT 10-7. EXAMPLE SERVICE VOLUMES FOR URBAN STREETS

(SEE FOOTNOTES FOR ASSUMED VALUES)This table containsapproximate values. It is

meant for illustrativepurposes only. The valuesare highly dependent onthe assumptions used. Itshould not be used foroperational analyses orfinal design. This tablewas derived usingassumed values listed inthe footnote.

Service Volumes (veh/h)

Lanes A B C D EClass I

1 N/ A 830 940 1030 1130

2 N/ A 1690 1900 2060 2270

3 N/ A 2550 2850 3110 3400

4 N/ A 3410 3800 4150 4530

Class II

1 N/ A N/ A 710 840 870

2 N/ A N/ A 1540 1690 1750

3 N/ A N/ A 2370 2540 2630

4 N/ A N/ A 3210 3390 3510

Class III

1 N/ A N/ A 570 800 8302 N/ A N/ A 1230 1610 1680

3 N/ A N/ A 1930 2430 2520

4 N/ A N/ A 2650 3240 3360

Class IV

1 N/ A N/ A N/ A 660 780

2 N/ A N/ A N/ A 1460 1570

3 N/ A N/ A N/ A 2260 2370

4 N/ A N/ A N/ A 3050 3170

NotesN/A - not achievable given assumptions below.This table was derived from the conditions listed in the following table.

Class

I II III IVSignal density (sig/km) 0.5 2 3 6Free-flow speed (km/h) 80 6 5 5 5 45Cycle length (s) 110 9 0 8 0 70Effective green ratio 0.45 0.45 0.45 0.45Adj. sat. flow rate 1850 1800 1750 1700Arrival type 3 4 4 5Unit extension (s) 3 3 3 3Initial queue 0 0 0 0Other delay 0 0 0 0Peak-hour factor 0.92 0.92 0.92 0.92% lefts, % rights 10 1 0 1 0 10Left-turn bay Yes Yes Yes YesLane utilization factor According to Exhibit 10-23, Default Lane Utilization

Factors


10/19

7/7/2005

Replace Exhibit 12-7b with the following figure:

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000

Directional Flow Rate (pc/h)

P

ercentTime-Spent-Following

Opposing Flow = 200 pc/h

Opposing Flow = 1600 pc/h


11/19

7/7/2005

Replace Exhibit 20-12 with the following:

Exhibit 20-12. Adjustment (fnp) To Percent Time-Spent Following for Percentage of No-

Passing Zones in Directional Segments

Two-way Increase in percent time-spent-following (%)

flow rate, No-passing zones (%)

vp (pc/h) 0 20 40 60 80 100

Directional split = 50/50

200 9.0 29.2 43.4 49.4 51.0 52.6

400 16.2 41.0 54.2 61.6 63.8 65.8

600 15.8 38.2 47.8 53.2 55.2 56.8

800 15.8 33.8 40.4 44.0 44.8 46.6

1400 12.8 20.0 23.8 26.2 27.4 28.6

2000 10.0 13.6 15.8 17.4 18.2 18.8

2600 5.5 7.7 8.7 9.5 10.1 10.3

3200 3.3 4.7 5.1 5.5 5.7 6.1Directional split = 60/40

200 11.0 30.6 41.0 51.2 52.3 53.5400 14.6 36.1 44.8 53.4 55.0 56.3

600 14.8 36.9 44.0 51.1 52.8 54.6

800 13.6 28.2 33.4 38.6 39.9 41.3

1400 11.8 18.9 22.1 25.4 26.4 27.3

2000 9.1 13.5 15.6 16.0 16.8 17.3


200 9.9 28.1 38.0 47.8 48.5 49.0

400 10.6 30.3 38.6 46.7 47.7 48.8

600 10.9 30.9 37.5 43.9 45.4 47.0

800 10.3 23.6 28.4 33.3 34.5 35.5

1400 8.0 14.6 17.7 20.8 21.6 22.3


200 8.9 27.1 37.1 47.0 47.4 47.9400 6.6 26.1 34.5 42.7 43.5 44.1600 4.0 24.5 31.3 38.1 39.1 40.0800 4.8 18.5 23.5 28.4 29.1 29.8

1400 3.5 10.3 13.3 16.3 16.9 32.22000 3.5 7.0 8.5 10.1 10.4 10.7

Directional split = 90/10

200 4.6 24.1 33.6 43.1 43.4 43.6

400 0.0 20.2 28.3 36.3 36.7 37.0600 -3.1 16.8 23.5 30.1 30.6 31.1800 -2.8 10.5 15.2 19.9 20.3 20.8

1400 -1.2 5.5 8.3 11.0 11.5 11.9


12/19

7/7/2005

Replace Exhibit 20-21 with the following:

Exhibit 20-21. Values of Coefficients Used in Estimating Percent Time-Spent

Following for Directional Segments.

Opposing demand flow rate, vo (pc/h) a b

200 0.0014 0.973

400 0.0022 0.923600 0.0033 0.870

800 0.0045 0.833

1000 0.0049 0.829

1200 0.0054 0.825

1400 0.0058 0.821

1600 0.0062 0.817

Replace Equation 20-16 with the following:

where:

PTSFd = percent time-spent-following in the direction analyzed,

BPTSFd = base percent time-spent-following in the direction analyzed,fnp = adjustment for percent no-passing zones in the direction analyzed

Vd = directional passenger-car equivalent flow rate (pc/h)

V0 = opposing direction passenger-car equivalent flow rate (pc/h)

++=

0d

dnpdd

VV

VfBPTSFPTSF


13/19

Highway Capacity Manual 2000

23-5 Chapter 23 - Basic Freeway SegmentsMethodology

fN

= adjustment for number of lanes from Exhibit 23-6 (mi/h); and

fID

= adjustment for interchange density from Exhibit 23-7 (mi/h).

EXHIBIT 23-3. SPEED-FLOW CURVES AND LOS FOR BASIC FREEWAY SEGMENTS

0 400 800 1200 1600 2000 2400

Flow Rate (pc/h/ln)

AveragePassenger-CarSpeed(mi/h)

80

70

60

50

40

30

20

10

0

C

13001450

1600

1750

LOS A B D E

Free-Flow Speed, FFS = 75 mi/h

70 mi/h

65 mi/h

60 mi/h

55 mi/h

Den

sity

=11

pc/m

i/ln

18pc/mi/l

n

26pc

/mi/ln

35pc/

mi/ln

45pc/mi

/ln

Note:Capacity varies by free-flow speed. Capacity is 2400, 2350, 2300, and 2250 pc/h/ln at free-flow speeds of 70 and greater, 65,60, and 55 mi/h, respectively.For 70 < FFS 75

(3400 30FFS) < vp 2400

S = FFS FFS160

3

vp + 30FFS 3400

30FFS 1000

2.6

For 55 FFS 70 and for flow rate (vp

)

(3400 30FFS) < vp (1700 + 10FFS),

S = FFS1

9 7FFS 340( )vp + 30FFS 3400

40FFS 1700

2.6

For 55 FFS 75 andvp (3400 30FFS),S = FFS

BFFS

Estimation of FFS for an existing or future freeway segment is accomplished by

adjusting a base free-flow speed downward to reflect the influence of four factors: lane

width, lateral clearance, number of lanes, and interchange density. Thus, the analyst is

required to select an appropriate BFFS as a starting point.

Adjustment for Lane Width

The base condition for lane width is 12 ft or greater. When the average lane width

across all lanes is less than 12 ft, the base free-flow speed (e.g., 75 mi/h) is reduced.

Adjustments to reflect the effect of narrower average lane width are given in Exhibit

23-4.


14/19

Highwa y Ca pa c ity Manua l 2000

Chapter 30 - Areawide Analysis 30-6Methodology

where

c = capacity (veh/h),

PHF = peak-hour factor, and

g/C = effective green time per cycle.

Refer to Equation 16-4 for definitions of all other factors.

See Chapter 16, Signalized Intersections, for the adjustment factor values. SeeChapter 10, Urban Street Concepts, for default values and approximation procedures

for adjustment factors.

For arterials with all-way stops controlling the link capacity, procedures in Chapter

17, Unsignalized Intersections, should be used to estimate the through movement

capacity at each intersection.

Capacity Tables

The accuracy of the speed estimates are highly dependent on the accuracy of the

estimated capacity for the facility. Consequently, it is recommended that each analyst use

capacities that are specific to each link whenever possible. However, it is recognized that

this procedure is not always feasible. The analyst may select sets of default values for the

various capacity adjustment factors that vary by functional class (freeway, highway,

arterial, collector, local), area type (downtown, urban, suburban, rural), terrain type(level, rolling, mountainous), and other conditions. These default values may be

substituted into the above capacity equations to develop tables of link capacity values that

vary by functional class, area type, general terrain, and number of lanes.

Determining Link SpeedTraversal time plus nodedelay equals segmenttravel time

The vehicle speed for the link is computed using Equation 30-4.

S =L

R +D

3600

(30-4)

where

S = link speed (mi/h),

L = link length (mi),R = link traversal time (h), and

D = node delay for link (s).

See Appendix A formethods to estimatenode delay

Node delay is computed only for signal- or stop-sign-controlled intersections at the

end of the link. All other intersection-related delays that occur in the middle of the link

are incorporated into the link traversal time calculation. The node delay estimation

procedure is described in Appendix A. The calculation requires information on all of the

intersection approaches at the node in order to compute the delay on each link feeding the

intersection.

If the available travel demand model software package is unable to compute node

delay, it can be approximated by using the node approach capacity rather than the link

capacity in the computation of traversal time. In this situation the node delay is set to

zero in Equation 30-4.The link traversal time, R, is computed using Equation 30-5.

R = Ro + Do +0 .25T (X 1) + (X 1)2 +

16 J * X * L2

T 2

(30-5)

where

R = link traversal time (h),Ro = link traversal time at link FFS (h),

Do = zero-flow control delay at signalized intersection (h),

See following page fornew equation


15/19

Revisions

[new equation]

(30-5)

( )

+

++++=

22

2*162)1(

125.0 TN

LXJXXNTDDRR

Moo

where: [add the following]

DM = segment delay between signals (equals zero if no signals)(h)

N = number of Signals (equals one if no signals)


16/19

Highw ay C ap ac ity Manua l 2000

30-7 Chapter 30 - Areawide AnalysisMethodology

T = expected duration of demand (typically 1 h) (h),

X = link demand to capacity ratio,

J = calibration parameter, and

L = link length (mi).

The link traversal time for free-flow conditions (Ro) is computed from the FFS,

using Equation 30-6.

Ro =L

So(30-6)

whereRo = FFS link traversal time (h),

L = link length (mi), andSo = link FFS (mi/h).

The zero-flow control delay for signalized intersections (if any) on the link is

computed using Equation 30-7.

Do =N

3600* DF *

C

21

g

C

2

(30-7)

whereDo = zero-flow control delay at signal (h),

N = number of signals on link,

3600 = conversion from seconds to hours,

g/C = average effective green time per cycle for signals on link (see Exhibit

10-12 for default values) (s),

C = average cycle length for all signals on link (see Exhibit 10-12 for

default values) (s), and

DF = adjustment factor to compute zero-flow control delay (0.9 for

uncoordinated traffic-actuated signals, 1.0 for uncoordinated fixed-time

signals, 1.2 for coordinated signals with unfavorable progression, 0.90

for coordinated signals with favorable progression, and 0.60 for

coordinated signals with highly favorable progression).

Calibration parameter J isused to arrive at a predictedmean speed when demandequals capacity

The calibration parameter J is selected so that the traversal time equation will predict

the mean speed of traffic when demand is equal to capacity. Substituting x = 1.00 in the

traversal time equation and solving for J yields Equation 30-8:

J =(Rc Ro )

2

L2(30-8)

where

J = calibration parameter,Rc = link traversal time when demand equals capacity (h),

Ro = FFS link traversal time (h), and

L = link length (mi).

See Appendix C foralternative approach usingBPR curve

Exhibit 30-4 shows values for J that were selected to reproduce the traversal times at

capacity predicted by the analysis procedures in Part III of this manual. Some older

software may not be able to implement Equation 30-8, so the formula and recommended

parameters for the more traditional BPR curve are provided in Appendix C as an

alternative method for estimating link traversal times.

Place "Note that the free flow speed..." text on the following page here.

Place "Insert 1" text here

See new equation for 30-8


17/19

(30-6)

Note that the free flow speed (SO) for signalized streets is defined as the mid-block free flow

speed between signals. For this reason a zero flow control delay (DO) and a segment delay (DM)

are added to the link travel time at zero flow.

(30-7)

Insert 1:The segment delay between signals (DM) is computed by subtracting the Segment Running Time

per mile (TR) (obtained from Exhibit 15-3) from the free flow travel time per mile for the

signalized urban street and multiplying the result by the total length of the street.DM equals zero

if there are no signals on the street or if they are so far apart that they do not affect the speed of

traffic between signals.

The segment delay (DM) is computed according to Equation 30-7a.

3600)(oRMTTLD = (30-7a)


DM= segment delay (h)

L = link length (mi)

TR= running time per mile (sec)

TO = running time per mile at free flow speed (sec)

The running time per mile (TR) is obtained from Exhibit 15-3 according to the urban street class,

free flow speed, and the average distance between signals on the link.

The running time per mile at free flow speed (TO) is computed according to Equation 30-7b.

ooSLT = (30-7b)

where:

L = Link length (mi)

TO= running time per mile at free flow speed (sec)

SO= free flow speed (mi/h)

(30-8)

( )2

2

L

DDRRJ

Mooc =


D0= zero flow control Delay (h)

DM= segment delay between signals (h)


18/19

Highwa y Ca pa c ity Manua l 2000

Chapter 30 - Areawide Analysis 30-8Methodology

EXHIBIT 30-4. RECOMMENDED PARAMETERS FOR TRAVERSAL TIME J

Facility Type Signals per mi Free- Flow Speed(mi/h)

Speed at Capacity(mi/h)

J(h2/mi2)

Freeway N/A 75 54 2.69 x 10-5

Freeway N/A 70 53 2.10 x 10-5

Freeway N/A 65 52 1.48 x 10-5

Freeway N/A 60 51 8.65 x 10-6Freeway N/A 55 50 3.31 x 10-6

Multilane Highway N/A 60 55 2.30 x 10-6




Two-Lane Highway N/A 69 44 6.91 x 10-5





Arterial Class I 0.2 50 33 5.67 x 10-5



Arterial Class II 0.3 40 25 1.28 x 10-4



Arterial Class III 1.3 35 11 2.24 x 10-3



Arterial Class IV 2.5 30 6 8.12 x 10-3



Note:N/A = not applicable.

Determining Performance Measures

Computation of performance measures for intensity, duration, extent, variability, and

accessibility is described.

Intensity

The possible performance measures for measuring the intensity of congestion on one

of the highway subsystems (freeway, rural highway, and arterial) are computed from one

or more of the following: person-hours of travel, person-hours of delay, mean trip speed,

and mean trip delay. If average vehicle occupancy (AVO) data are not available, the

performance measures are computed in terms of vehicle-hours rather than person-hours.

Equation 30-9 is used to compute person-hours of travel.

PHT = AVOi *v i *LiSi

(30-9)

where

PHT = total person-hours of travel,vi = vehicle demand on Link i,

AVOi = average vehicle occupancy on Link i,

Li = length of Link i (mi), and

Si = mean speed of Link i (mi/h).

See revised Exhibit30-4 on the followingpage


19/19

Revised information for:EXHIBIT 30-4. RECOMMENDED PARAMETERS FOR TRAVERSAL TIME J

Facility type Signals per mi Free-Flow Speed Speed at CapacityJ

(h2/mi2)FreewayFreeway

FreewayFreewayFreeway

53 2.95 x 10-5

Multilane HighwayMultilane HighwayMultilane HighwayMultilane Highway

Two-Lane HighwayTwo-Lane HighwayTwo-Lane HighwayTwo-Lane HighwayTwo-Lane Highway

6560555045

4035302520

9.04 x 10-5

1.39 x 10-4

2.24 x 10-4

3.89 x 10-4

7.48 x 10-4

Arterial Class I

Arterial Class IArterial Class I

0.5

2.04.0

2.21 x 10-5

2.04 x 10-4

1.25 x 10-3

Arterial Class IIArterial Class IIArterial Class II

1.02.03.0

4.99 x 10-5

2.00 x 10-4

7.91 x 10-4

Arterial Class IIIArterial Class IIIArterial Class III

3.05.06.0

8.01 x 10-4

1.78 x 10-3

3.18 x 10-3Arterial Class IVArterial Class IVArterial Class IV

6.08.010.0

3.17 x 10-3

4.99 x 10-3

7.11 x 10-3

Note:N/A = not applicable

[please add the following]

This table is provided for the convenience of the analyst and should be considered approximate.Precise values of J can be computed using Equation 30-8.

Documents

Approved Corrections to HCM 2000 Jul 2005