Highway Capacity Manual 2000
17-49 Chapter 17 - Unsignalized IntersectionsExample Problems
PART D. EXAMPLE PROBLEMS
Problem No. Description Application
1 TWSC Unsignalized Intersection Operational LOS2 TWSC Unsignalized Intersection Operational LOS3 TWSC Unsignalized Intersection Operational LOS4 AWSC Unsignalized Intersection Operational LOS5 AWSC Unsignalized Intersection Operational LOS6 Roundabout Capacity and v/c ratio
Highway Capacity Manual 2000
Chapter 17 - Unsignalized Intersections 17-50Example Problems
EXAMPLE PROBLEM 1
The Intersection A TWSC T-intersection with an exclusive westbound left-turn lane.
The Question What are the delay and level of service?
The Facts√ Two-lane major street, √ 10 percent HV,√ Two-lane minor street, √ No special intersection geometry, and√ Level grade, √ No pedestrians.√ Stop-controlled on minor street
approach,
Outline to Solution The steps below show the northbound approach calculations only.Calculations for other approaches are shown on the worksheets.
Steps1. Data input. Worksheets 1 and 2
2. Site characteristics. Worksheet 3 - lane designation, grade, right-turn channelization, and arrival type
3. tc and tf (use Equations 17-1 and17-2 and Exhibit 17-5 ).
tc,x = tc,base + tc,HV PHV + tc,G G – tc, T – t3,LT
tf,x = tf,base + tf,HV PHV
tc,4 = 4.1 + 1.0(0.10) + 0 – 0 – 0 = 4.200 s
tf,x = 2.2 + 0.9(0.10) = 2.290 s
4. Skip Worksheets 5a through 5e. No upstream signals within 0.4 km
5. Movement capacity cm,x accountingfor impedance (use Equation 17-4 ). vc,9 =
v2N + 0.5v3 + v14 + v15
vc,9 = 250 + 20 + 0 + 0 = 270 veh/h
cp,x = vc,xe−vc,xtc,x /3,600
1− e−vc,xtf,x /3,600
cp,9 = 270 *e−270*6.300/3,600
1− e−270*3.390/3,600 = 750 veh/h
cm,9 = cp,9 * Pp,9 = 750 (1) = 750 veh/h
P0,i = 1− vi
cm,i
P0,9 = 1− 120750
= 0.840
6. Skip Worksheets 7a and 7b. No two-stage gap acceptance
7. Shared-lane capacity (use Equation17-15).
Worksheet 8 - Movements 7 and 9 share thesame lane
cSH =vy
y∑
vy
cm,yy∑
cSH(NB) =40 +12040
274+ 120
750
=523 veh/h
8. Skip Worksheet 9. No flared minor-street approach
Highway Capacity Manual 2000
17-51 Chapter 17 - Unsignalized IntersectionsExample Problems
9. Control delay and LOS (useEquation 17-38 and Exhibit 17-2).
Worksheet 10
d = 3,600cm,x
+ 900T[... ] + 5
dNB =3,600523
+ 900 0.25( )[... ] + 5 = 14.9 s,
LOS B
10. Skip Worksheet 11. No Rank 1 vehicle delay
Example Problem 1
STOP
STOP
v1v2v3
v12
v7
v10
v9
v13
v14v15
v16v6
v4S2
S5
v11
v8
v5
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 1
Worksheet 2
Vehicle Volumes and Adjustments
Pedestrian Volumes and Adjustments
Vehicle Volumes and Adjustments
Movement 1 2 3 4 5 6 7 8 9 10 11 12
Volume (veh/h)
Peak-hour factor, PHF
Hourly flow rate (veh/h)
Proportion of heavy vehicles, PHV
Movement 13 14 15 16
Flow, Vx (ped/h)
Lane width, w (m)
Walking speed,1 Sp (m/s)
Percent blockage, fp (Equation 17-11)
1. Default walking speed = 1.2 m/s
General Information Site Information
Analyst ______________________ Intersection ________________________Agency or Company ______________________ Jurisdiction ________________________Date Performed ______________________ Analysis Year ________________________Analysis Time Period ______________________
Geometrics and Movements
Length of study period = _____ h
grade = ______
grade = ______
grade = ______
grade = ______
Show NorthStre
et
Street
KMN Jones/MarketCEI Latah County5/17/99 1999AM Peak
Jone
s
Market
25040
300150
40 120
250 40 150 300 40 120
1.00 1.00 1.00 1.00 1.00 1.00
250 40 150 300 40 120
0.10 0.10 0.10 0.10 0.10 0.10
0%
0.25
0%
0%
0 0 0 0
Chapter 17 - Unsignalized Intersections 17-52Example Problems
Highway Capacity Manual 2000
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 3
Movement 9 " Yes " No Storage space, n ________________(number of vehicles)
Movement 12 " Yes " No Storage space, n ________________(number of vehicles)
Type
Movements 7 and 8 " Yes _____ " No Storage space, m ________________(number of vehicles)
Movements 10 and 11 " Yes _____ " No Storage space, m ________________(number of vehicles)
* Includes raised or striped median (RM), or two-way left-turn lane (TWLTL)
Lane Designation
Movements Lane 1 Lane 2 Lane 3 Grade, G Right TurnChannelized?
1, 2, 3
4, 5, 6
7, 8, 9
10, 11, 12
Flared Minor-Street Approach
Median Storage*
Computing Delay to Major-Street Vehicles
Upstream Signals
Data for Computing Effect of Delay to Major-Street Vehicles S2 Approach S5 Approach
Shared-lane volume, major-street through vehicles, vi1, blocked by LT
Shared-lane volume, major-street right-turn vehicles, vi2, blocked by LT
Saturation flow rate, major-street through vehicles, si1
Saturation flow rate, major-street right-turn vehicles, si2
Number of major-street through lanes
Length of study period, T (h)
Movements Distance to Prog Speed, Cycle Green Time, Arrival Saturation Flow Progressed Flow,Signal, D (m) Sprog (km/h) Length, C (s) geff (s) Type Rate, s (veh/h) Vprog (veh/h)
protected LT 3
TH
protected LT 3
TH
S2
S5
General Information
Project Description _________________________________________________________________________________
Example Problem 1
2, 3 0 N
4 5 0 N
7, 9 0 N
X
X
X
X
Example Problem 1
Highway Capacity Manual 2000
17-53 Chapter 17 - Unsignalized IntersectionsExample Problems
tf = tf,base + tf,HV PHV
tc = tc,base + tc,HV PHV + tc,G G - tc,T - t3,LT
Major LT Minor RT Minor TH Minor LT
Movement 1 4 9 12 8 11 7 10
tf,base (Exhibit 17-5)
tf,HV
PHV (from Worksheet 2)
tf (Equation 17-2)
Worksheet 5a
Time to Clear Standing Queue (Computation 1)
Movement 2 Movement 5vT,prog vL,prot vT,prog vL,prot
Effective green, geff (s)
Cycle length, C (s)
Saturation flow rate, s (veh/h)
Arrival type 3 3
vprog (veh/h)
Rp (from Chapter 16) 1.00 1.00
Proportion of vehicles arrivingon green, P (Equation 17-17)
gq1 (Equation 17-18)
gq2 (Equation 17-19)
gq (Equation 17-20)
Major LT Minor RT Minor TH Minor LTMovement 1 4 9 12 8 11 7 10
tc,base (Exhibit 17-5)
tc,HV
PHV (from Worksheet 2)
tc,G - - 0.1 0.1 0.2 0.2 0.2 0.2
G (from Worksheet 3)t3,LT
single stage
two stage
single stage
two stage
tc,T
tc (Equation 17-1)
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 4
Critical Gap and Follow-Up Time
General Information
Project Description _________________________________________________________________________________
Example Problem 1
4.1 6.2 7.11.0 1.0 1.00.10 0.10 0.10
0 0 00.0 0.0 0.70.0 0.0 0.0
4.200 6.300 6.500
2.2 3.3 3.50.9 0.9 0.90.10 0.10 0.102.290 3.390 3.590
Example Problem 1
Chapter 17 - Unsignalized Intersections 17-54Example Problems
Highway Capacity Manual 2000
7
7
7
10
10
10
0,4 0,1
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 6
Step 1: RT from Minor Street v9 v12
Conflicting flows (Exhibit 17-4) vc,9 = vc,12 =
Potential capacity (Equation 17-3 or 17-29) cp,9 = cp,12 =
Ped impedance factor (Equation 17-12) pp,9 = pp,12 =
Movement capacity (Equation 17-4) cm,9 = cp,9 pp,9 = cm,12 = cp,12 pp,12 =
Prob of queue-free state (Equation 17-5) p0,9 = p0,12 =
Step 2: LT from Major Street v4 v1
Conflicting flows (Exhibit 17-4) vc,4 = vc,1 =
Potential capacity (Equation 17-3 or 17-29) cp,4 = cp,1 =
Ped impedance factor (Equation 17-12) pp,4 = pp,1 =
Movement capacity (Equation (17-4) cm,4 = cp,4 pp,4 = cm,1 = cp,1 pp,1 =
Prob of queue-free state (Equation 17-5) p0,4 = p0,1 =
Major left shared lane prob of queue-free state (Equation 17-16) p* = p* =
Step 3: TH from Minor Street (4-leg intersections only) v8 v11
Conflicting flows (Exhibit 17-4) vc,8 = vc,11 =
Potential capacity (Equation 17-3 or 17-29) cp,8 = cp,11 =
Ped impedance factor (Equation 17-12) pp,8 = pp,11 =
Capacity adjustment factor due to impeding movement f8 = p0,4 p0,1 pp,8 = f11 = p0,4 p0,1 pp,11 =(shared lane use p*) (Equation 17-13)
Movement capacity (Equation 17-7) cm,8 = cp,8 f8 = cm,11 = cp,11 f11 =
Prob of queue-free state p0,8 = p0,11 =
Step 4: LT from Minor Street (4-leg intersections only) v7 v10
Conflicting flows (Exhibit 17-4) vc,7 = vc,10 =
Potential capacity (Equation 17-3 or 17-29) cp,7 = cp,10 =
Ped impedance factor (Equation 17-12) pp,7 = pp,10 =
Major left, minor through impedance factor p'' = p0,11 f11 = p'' = p0,8 f8 =
Major left, minor through adjusted impedance factor p' = p'
=(Equation 17-8)
Capacity adjustment factor due to impeding movements f7 = p' p0,12 pp,7 = f10 = p' p0,9 pp,10 =
(Equation 17-14)
Movement capacity (Equation 17-10) cm,7 = f7 cp,7 = cm,10 = f10 cp,10 =
Step 5: LT from Minor Street (T-intersections only) v7 v10
Conflicting flows (Exhibit 17-4) vc,7 = vc,10 =
Potential capacity (Equation 17-3 or 17-29) cp,7 = cp,10 =
Ped impedance factor (Equation 17-12) pp,7 = pp,10 =
Capacity adjustment factor due to impeding movement f7 = p0,4 p0,1 pp,7 = f10 = p0,4 p0,1 pp,10 =(shared lane use p*) (Equation 17-13)
Movement capacity (Equation 17-7) cm,7 = cp,7 f7 = cm,10 = cp,10 f10 =
Impedance and Capacity Calculation
General Information
Project Description _________________________________________________________________________________
Notes
1. For 4-leg intersections use Steps 1, 2, 3, and 4.2. For T-intersections use Steps 1, 2, and 5.
2707501.000
7500.840 1.000
29012271.000
12270.878 1.000
8703121.000
0.878
274
Example Problem 1
Example Problem 1
Highway Capacity Manual 2000
17-55 Chapter 17 - Unsignalized IntersectionsExample Problems
Example Problem 1
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 8
Movement v (veh/h) cm (veh/h) cSH (veh/h)
7
8
9
10
11
12
Worksheet 9
Movement 7 Movement 8 Movement 9 Movement 10 Movement 11 Movement 12
csep (from Worksheet 6 or 7)
Volume (from Worksheet 2)
Delay (Equation 17-38)
Qsep (Equation 17-34)
Qsep + 1
Round (Qsep + 1)
nmax (Equation 17-35)
cSH
csep
n
cact (Equation 17-36)
Effect of Flared Minor-Street Approaches
Shared-Lane Capacity
General Information
Project Description _________________________________________________________________________________
(Equation 17-15)cSH =
∑vy
∑
y
yvy
cm,y( )
40 274
523
120 750
Example Problem 1
Chapter 17 - Unsignalized Intersections 17-56Example Problems
Highway Capacity Manual 2000
Example Problem 1
*
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 10
Delay to Rank 1 Vehicles
Worksheet 11
Control Delay, Queue Length, Level of Service
S2 Approach S5 Approach
p0,j (Equation 17-5)
vi1, volume for Stream 2 or 5
vi2, volume for Stream 3 or 6
si1, saturation flow rate for Stream 2 or 5
si2, saturation flow rate for Stream 3 or 6
p0,j (Equation 17-16)
dmajor left, delay for Stream 1 or 4
N, number of major-street through lanes
dRank 1, delay for Stream 2 or 5 (Equation 17-39)
Lane v (veh/h) cm (veh/h) v/c Queue Length Control Delay LOS Delay and LOS(Equation 17-37) (Equation 17-38) (Exhibit 17-2)
1
2
3
1
2
3
Movement v (veh/h) cm (veh/h) v/c Queue Length Control Delay LOS(Equation 17-37) (Equation 17-38) (Exhibit 17-2)
1
4
General Information
Project Description _________________________________________________________________________________
121110
121110
121110
987
987
987
p0,1 = p0,4 =
p* = p* =0, 1 0, 4
Example Problem 1
160 523 0.306 < 2 14.9 B 14.9B
X X X
150 1227 0.12 < 1 8.3 A
Highway Capacity Manual 2000
17-57 Chapter 17 - Unsignalized IntersectionsExample Problems
EXAMPLE PROBLEM 2
The Intersection A TWSC intersection with upstream signals. The major street isWalnut St. (EB/WB) and the minor street is Elm St. (NB/SB).
The Question What are the delay and level of service of the minor-street approaches?
The Facts√ Four-lane major street, √ 10 percent HV,√ Two-lane minor street, √ Upstream signals in both major-street directions, and√ Level grade, √ No pedestrians.
Outline to Solution The steps below show the northbound approach calculations only.Calculations for other approaches are shown on the worksheets.
Steps1. Data input. Worksheets 1 and 22. Site characteristics. Worksheet 3 - lane designation, grades, right-turn
channelization, and upstream signals3. tc and tf (s) (use
Equations 17-1 and 17-2 and Exhibit 17-5).
tc,x = tc,base + tc,HV PHV + tc,G G – tc, T – t3,LT
tc,1 = 4.1 + 2.0(0.10) + 0 – 0 – 0 = 4.300 s
tf,x = tf,base + tf,HV PHV
tf,x = 2.2 + 1.0(0.10) = 2.300 s
4. Effect of upstreamsignals
Worksheets 5a through 5e
Proportion of vehiclesarriving during green, P(use Equation 17-17).
P = Rp
geffC
P = 0.33 3080 = 0.124
Discharge time (useEquations 17-18, 17-19, and 17-20 ).
For Movement 2gq = gq1 + gq2
gq1 =vprogC(1−P)
s= 250(80)(1− 0.124)
3,600= 4.867
gq2 =vprogCPgq1
sgeff − vprogCP= 250(80)(0.124)(4.867)
3,600(30) − 250(80)(0.124)= 0.114
gq = 4.867 + 0.114 = 4.981
Maximum platoon flowrate, vc,max (useEquation 17-21).
vc,max = sf[1 – (1 – F)gq]
vc,max = 3,600(0.751)[1 – (1 – 0.253)4.981] = 2,071 veh/h
Minimum platoon flowrate, vc,min.
vc,min = 1,000(2) = 2,000
Duration of blockedperiod, tp,i (useEquation 17-22).
tp,i = gq −
ln 1−vc,min
sf
vc,max − vprogRpf
vc,min − vprogRpf
ln(1−F)
tp,2 = 4.981−ln 1− 2,000
3,600(0.751)
2,071−250(0.33)(0.751)2,000 −250(0.33)(0.751)
ln(1−0.253)=
0.489
Proportion of timeblocked (use Equation17-23).
pi =tP,T + tP,L
C
p2 = 0.489
80 = 0.006
Highway Capacity Manual 2000
Chapter 17 - Unsignalized Intersections 17-58Example Problems
4. (continued) Dominantand subordinateplatoons (useEquations 17-24 and17-25).
pdom = max(p2, p5)
psubo = min(p2, p5)
pdom = P2 = 0.006
psubo = P5 = 0.000
Conflicting flow duringunblocked period (useEquation 17-28).
vc,u,x =vc,x − s(1− px )
px
vc,u,1 =400 − 3,600(1−1.000)
1.000=400 veh/h
Capacity duringunblocked period, cr,x(use Equation 17-3).
cr,x = vc,u,xe−vc,u,xtc,x /3,600
1− e−vc,u,xtf,x /3,600
cr,1 = 400e−400(4.300)/3,600
1− e−400(2.300)/3,600 =1,100 veh/h
Potential capacity,cplat,x, accounting forplatooning (useEquation 17-29).
cplat,x = px cr,x
cplat,1 = 1.000(1,100) = 1,100 veh/h
5. Movement capacity,cm,x, accounting forimpedance (useEquation 17-4, 17-7, or17-10).
cm,x = cplat,x fxcm,1 = 1,100(1.000) = 1,100 veh/h
6. Skip Worksheets 7aand 7b.
No two-stage gap acceptance
7. Shared-lane capacityWorksheet 8 (useEquation 17-15). cSH =
vyy∑
vy
cm,yy∑
cSH(NB) =44 +132 + 55
44202
+ 132254
+ 55867
=288 veh/h
8. Skip Worksheet 9. No flared minor-street approaches9. Control delay and LOS
(use Equation 17-38and Exhibit 17-2).
d = 3,600cm,x
+ 900T[... ] + 5
dNB =3,600288
+ 900 0.25( )[... ] + 5 = 53.5 s , LOS F
10. Skip Worksheet 11. No Rank 1 vehicle delay
Highway Capacity Manual 2000
17-59 Chapter 17 - Unsignalized IntersectionsExample Problems
Example Problem 2
STOP
STOP
v1v2v3
v12
v7
v10
v9
v13
v14v15
v16v6
v4S2
S5
v11
v8
v5
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 1
Worksheet 2
Vehicle Volumes and Adjustments
Pedestrian Volumes and Adjustments
Vehicle Volumes and Adjustments
Movement 1 2 3 4 5 6 7 8 9 10 11 12
Volume (veh/h)
Peak-hour factor, PHF
Hourly flow rate (veh/h)
Proportion of heavy vehicles, PHV
Movement 13 14 15 16
Flow, Vx (ped/h)
Lane width, w (m)
Walking speed,1 Sp (m/s)
Percent blockage, fp (Equation 17-11)
1. Default walking speed = 1.2 m/s
General Information Site Information
Analyst ______________________ Intersection ________________________Agency or Company ______________________ Jurisdiction ________________________Date Performed ______________________ Analysis Year ________________________Analysis Time Period ______________________
Geometrics and Movements
Length of study period = _____ h grade = ______
grade = ______
grade = ______
grade = ______
Show NorthStre
et
Street
JME Walnut/ElmCEI Latah County5/7/99 1999AM Peak
28 110 11
100
300
66
44 132 55
33
250
50
33 250 50 66 300 100 44 132 55 11 110 28
1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000
33 250 50 66 300 100 44 132 55 11 110 28
0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
0 0 0 0
Walnut
Elm
0.25
0%
0%
0%
0%
Chapter 17 - Unsignalized Intersections 17-60Example Problems
Highway Capacity Manual 2000
Example Problem 2
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 3
Movement 9 " Yes " No Storage space, n ________________(number of vehicles)
Movement 12 " Yes " No Storage space, n ________________(number of vehicles)
Type
Movements 7 and 8 " Yes _____ " No Storage space, m ________________(number of vehicles)
Movements 10 and 11 " Yes _____ " No Storage space, m ________________(number of vehicles)
* Includes raised or striped median (RM), or two-way left-turn lane (TWLTL)
Lane Designation
Movements Lane 1 Lane 2 Lane 3 Grade, G Right TurnChannelized?
1, 2, 3
4, 5, 6
7, 8, 9
10, 11, 12
Flared Minor-Street Approach
Median Storage*
Computing Delay to Major-Street Vehicles
Upstream Signals
Data for Computing Effect of Delay to Major-Street Vehicles S2 Approach S5 Approach
Shared-lane volume, major-street through vehicles, vi1, blocked by LT
Shared-lane volume, major-street right-turn vehicles, vi2, blocked by LT
Saturation flow rate, major-street through vehicles, si1
Saturation flow rate, major-street right-turn vehicles, si2
Number of major-street through lanes
Length of study period, T (h)
Movements Distance to Prog Speed, Cycle Green Time, Arrival Saturation Flow Progressed Flow,Signal, D (m) Sprog (km/h) Length, C (s) geff (s) Type Rate, s (veh/h) Vprog (veh/h)
protected LT 3
TH
protected LT 3
TH
S2
S5
General Information
Project Description _________________________________________________________________________________
1 2 2, 3 0 N
4 5 5, 6 0 N
7, 8, 9 0 N
10, 11, 12 0 N
X
X
X
X
135 55 80.0 30.0 1 3600 250
200 50 70.0 20.0 1 3600 250
Example Problem 2
Highway Capacity Manual 2000
17-61 Chapter 17 - Unsignalized IntersectionsExample Problems
Example Problem 2
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 4
Critical Gap and Follow-Up Time
tc = tc,base + tc,HV PHV + tc,G G - tc,T - t3,LT
tf = tf,base + tf,HV PHV
Major LT Minor RT Minor TH Minor LT
Movement 1 4 9 12 8 11 7 10
tf,base (Exhibit 17-5)
tf,HV
PHV (from Worksheet 2)
tf (Equation 17-2)
tc,T
tc (Equation 17-1)
Worksheet 5a
Time to Clear Standing Queue (Computation 1)
Movement 2 Movement 5vT,prog vL,prot vT,prog vL,prot
Effective green, geff (s)
Cycle length, C (s)
Saturation flow rate, s (veh/h)
Arrival type 3 3
vprog (veh/h)
Rp (from Chapter 16) 1.00 1.00
Proportion of vehicles arrivingon green, P (Equation 17-17)
gq1 (Equation 17-18)
gq2 (Equation 17-19)
gq (Equation 17-20)
General Information
Project Description _________________________________________________________________________________
Major LT Minor RT Minor TH Minor LTMovement 1 4 9 12 8 11 7 10
tc,base (Exhibit 17-5)
tc,HV
PHV (from Worksheet 2)
tc,G - - 0.1 0.1 0.2 0.2 0.2 0.2
G (from Worksheet 3)t3,LT
single stage
two stage
single stage
two stage
4.1 4.1 6.9 6.9 6.5 6.5 7.5 7.52.0 2.0 2.0 2.0 2.0 2.0 2.0 2.00.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
0 0 0 0 0 0 0 00.0 0.0 0.0 0.0 0.0 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0- - - - - - - -4.300 4.300 7.100 7.100 6.700 6.700 7.700 7.700- - - - - - - -
2.2 2.2 3.3 3.3 4.0 4.0 3.5 3.51.0 1.0 1.0 1.0 1.0 1.0 1.0 1.00.10 0.10 0.10 0.10 0.10 0.10 0.10 0.102.300 2.300 3.400 3.400 4.100 4.100 3.600 3.600
30.0 20.080.0 70.03600 36001 1
250 2500.33 0.330.124 0.094
4.867 4.4040.114 0.103
4.981 4.507
Example Problem 2
Chapter 17 - Unsignalized Intersections 17-62Example Problems
Highway Capacity Manual 2000
Example Problem 2
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Proportion of Time TWSC Intersection Is Blocked (Computation 2)
Worksheet 5b
Movement 2 Movement 5
vT,prog vL,prot vT,prog vL,prot
α (Exhibit 17-13)
β = (1 + α)-1
ta = D/Sprog (s)
F = (1 + αβta)-1
f = vprog/Vc ≥ 0
vc,Max (Equation 17-21)
vc,Min = 1000N
tp (Equation 17-22)
p (Equation 17-23)
Worksheet 5c
Platoon Event Periods (Computation 3)
General Information
Project Description _________________________________________________________________________________
p2 (from Worksheet 5b)
p5 (from Worksheet 5b)
pdom (Equation 17-24)
psubo (Equation 17-25)
Constrained or unconstrained (Equation 17-26, 17-27)
Proportion for Minor Movements, px
Single-Stage Two-Stage
(Exhibit 17-16) Stage I Stage II
p1
p4
p7 1 - p2 1 - p5
p8 1 - p2 1 - p5
p9
p10 1 - p5 1 - p2
p11 1 - p5 1 - p2
p12
0.50 0.50
0.667 0.667
8.836 14.400
0.253 0.172
0.751 0.536
2071 1105
2000 2000
0.489 0.000
0.006 0.000
0.006
0.000
0.006
0.000
Unconstrained
1.000
0.994
0.994
0.994
0.994
0.994
0.994
1.000
Example Problem 2
Highway Capacity Manual 2000
17-63 Chapter 17 - Unsignalized IntersectionsExample Problems
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 5d
Worksheet 5e
Conflicting Flows During Unblocked Period (Computation 4)
Two-Stage
Movements 7 8 10 11
Stage I Stage II Stage I Stage II Stage I Stage II Stage I Stage II
px (from Worksheet 5c)
cr,x (Equation 17-3)
cplat,x (Equation 17-29)
Single-Stage
Movements 1 4 7 8 9 10 11 12
vc,x (Exhibit 17-4)
s (veh/h)
px (from Worksheet 5c)
vc,u,x (Equation 17-28)
Single-Stage
Movements 1 4 7 8 9 10 11 12
px (from Worksheet 5c)
cr,x (Equation 17-3)
cplat,x (Equation 17-29)
Capacity During Unblocked Period (Computation 5)
Two-Stage
Movements 7 8 10 11
Stage I Stage II Stage I Stage II Stage I Stage II Stage I Stage II
vc,x (Exhibit 17-4)
s (veh/h)
px (from Worksheet 5c)
vc,u,x (Equation 17-28)
General Information
Project Description _________________________________________________________________________________
Example Problem 2
400 300 678 873 150 739 848 200
3600 3600 3600 3600 3600 3600 3600 3600
1.000 0.994 0.994 0.994 0.994 0.994 0.994 1.000
400 280 660 857 129 722 831 200
1.000 0.994 0.994 0.994 0.994 0.994 0.994 1.000
1100 1223 333 279 872 300 289 783
1100 1216 331 277 867 298 287 783
Example Problem 2
Chapter 17 - Unsignalized Intersections 17-64Example Problems
Highway Capacity Manual 2000
7
7
7
10
10
10
0,4 0,1
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 6
Step 1: RT from Minor Street v9 v12
Conflicting flows (Exhibit 17-4) vc,9 = vc,12 =
Potential capacity (Equation 17-3 or 17-29) cp,9 = cp,12 =
Ped impedance factor (Equation 17-12) pp,9 = pp,12 =
Movement capacity (Equation 17-4) cm,9 = cp,9 pp,9 = cm,12 = cp,12 pp,12 =
Prob of queue-free state (Equation 17-5) p0,9 = p0,12 =
Step 2: LT from Major Street v4 v1
Conflicting flows (Exhibit 17-4) vc,4 = vc,1 =
Potential capacity (Equation 17-3 or 17-29) cp,4 = cp,1 =
Ped impedance factor (Equation 17-12) pp,4 = pp,1 =
Movement capacity (Equation (17-4) cm,4 = cp,4 pp,4 = cm,1 = cp,1 pp,1 =
Prob of queue-free state (Equation 17-5) p0,4 = p0,1 =
Major left shared lane prob of queue-free state (Equation 17-16) p* = p* =
Step 3: TH from Minor Street (4-leg intersections only) v8 v11
Conflicting flows (Exhibit 17-4) vc,8 = vc,11 =
Potential capacity (Equation 17-3 or 17-29) cp,8 = cp,11 =
Ped impedance factor (Equation 17-12) pp,8 = pp,11 =
Capacity adjustment factor due to impeding movement f8 = p0,4 p0,1 pp,8 = f11 = p0,4 p0,1 pp,11 =(shared lane use p*) (Equation 17-13)
Movement capacity (Equation 17-7) cm,8 = cp,8 f8 = cm,11 = cp,11 f11 =
Prob of queue-free state p0,8 = p0,11 =
Step 4: LT from Minor Street (4-leg intersections only) v7 v10
Conflicting flows (Exhibit 17-4) vc,7 = vc,10 =
Potential capacity (Equation 17-3 or 17-29) cp,7 = cp,10 =
Ped impedance factor (Equation 17-12) pp,7 = pp,10 =
Major left, minor through impedance factor p'' = p0,11 f11 = p'' = p0,8 f8 =
Major left, minor through adjusted impedance factor p' = p'
=(Equation 17-8)
Capacity adjustment factor due to impeding movements f7 = p' p0,12 pp,7 = f10 = p' p0,9 pp,10 =
(Equation 17-14)
Movement capacity (Equation 17-10) cm,7 = f7 cp,7 = cm,10 = f10 cp,10 =
Step 5: LT from Minor Street (T-intersections only) v7 v10
Conflicting flows (Exhibit 17-4) vc,7 = vc,10 =
Potential capacity (Equation 17-3 or 17-29) cp,7 = cp,10 =
Ped impedance factor (Equation 17-12) pp,7 = pp,10 =
Capacity adjustment factor due to impeding movement f7 = p0,4 p0,1 pp,7 = f10 = p0,4 p0,1 pp,10 =(shared lane use p*) (Equation 17-13)
Movement capacity (Equation 17-7) cm,7 = cp,7 f7 = cm,10 = cp,10 f10 =
Impedance and Capacity Calculation
General Information
Project Description _________________________________________________________________________________
Notes
1. For 4-leg intersections use Steps 1, 2, 3, and 4.2. For T-intersections use Steps 1, 2, and 5.
150 200867 7831.000 1.000
867 783
0.937 0.964
300 400
1216 11001.000 1.000
1216 1100
0.946 0.970
873 848277 2871.000 1.000
0.917 0.917
254 2630.480 0.582
678 739331 298
1.000 1.0000.534 0.440
0.634 0.556
0.611 0.521
202 155
Example Problem 2
Example Problem 2
Highway Capacity Manual 2000
17-65 Chapter 17 - Unsignalized IntersectionsExample Problems
(Equation 17-15)vy
cm,y
cSH =
( )
∑vy
∑
y
y
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 8
Movement v (veh/h) cm (veh/h) cSH (veh/h)
7
8
9
10
11
12
Worksheet 9
Movement 7 Movement 8 Movement 9 Movement 10 Movement 11 Movement 12
csep (from Worksheet 6 or 7)
Volume (from Worksheet 2)
Delay (Equation 17-38)
Qsep (Equation 17-34)
Qsep + 1
Round (Qsep + 1)
nmax (Equation 17-35)
cSH
csep
n
cact (Equation 17-36)
Effect of Flared Minor-Street Approaches
Shared-Lane Capacity
General Information
Project Description _________________________________________________________________________________
Example Problem 2
44 202
132 254 288
55 867
11 155
110 263 284
28 783
Example Problem 2
Chapter 17 - Unsignalized Intersections 17-66Example Problems
Highway Capacity Manual 2000
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 10
Delay to Rank 1 Vehicles
Worksheet 11
Control Delay, Queue Length, Level of Service
S2 Approach S5 Approach
p0,j (Equation 17-5)
vi1, volume for Stream 2 or 5
vi2, volume for Stream 3 or 6
si1, saturation flow rate for Stream 2 or 5
si2, saturation flow rate for Stream 3 or 6
p0,j (Equation 17-16)
dmajor left, delay for Stream 1 or 4
N, number of major-street through lanes
dRank 1, delay for Stream 2 or 5 (Equation 17-39)
Lane v (veh/h) cm (veh/h) v/c Queue Length Control Delay LOS Delay and LOS(Equation 17-37) (Equation 17-38) (Exhibit 17-2)
1
2
3
1
2
3
Movement v (veh/h) cm (veh/h) v/c Queue Length Control Delay LOS(Equation 17-37) (Equation 17-38) (Exhibit 17-2)
1
4
General Information
Project Description _________________________________________________________________________________
Example Problem 2
121110
121110
121110
987
987
987
p0,1 = p0,4 =
p* = p* =0, 1 0, 4*
Example Problem 2
231 288 0.802 6 53.5 F 53.5F
149 284 0.525 3 30.9 D 30.9D
X X X
33 1100 0.030 - 8.4 A
66 1216 0.054 - 8.1 A
X X X
Highway Capacity Manual 2000
17-67 Chapter 17 - Unsignalized IntersectionsExample Problems
EXAMPLE PROBLEM 3
The Intersection A TWSC intersection with flared approaches and a median storage.The major street is Walnut St. (EB/WB), and the minor street is Elm St. (NB/SB).
The Question What are the delay and level of service of the minor-street approaches?
The Facts√ Four-lane major street, √ 10 percent HV,√ Two-lane minor street, √ Flared approach, storage for one vehicle, and√ Level grade, √ Median storage, storage for two vehicles.√ No pedestrians,
Outline to Solution The steps below show the northbound approach calculations only.Calculations for other approaches are shown on the worksheets.
Steps1. Data input. Worksheets 1 and 22. Site characteristics. Worksheet 3 - lane distribution, grades, right-turn
channelization, flared minor-street approach, andmedian storage
3. tc and tf (use Equations 17-1 and17-2).
Worksheet 4 - Movement 1tc = tc,base + tc,HV PHV +...
tc = 4.1 + 2.0(0.10) + 0.0 – 0.0 – 0.0 = 4.300 s
tf = tf,base + tf,HV PHV
tf = 2.2 + 1.0(0.10) = 2.300 s
4. Skip Worksheets 5a through 5e. No upstream signals within 0.4 km5. Movement capacity, cm,x, for
minor RT and major LTmovements accounting forimpedance (use Equations 17-3,17-4, 17-5, and 17-12).
Worksheet 6 - Movement 9
vc,9 = v2N + 0.5v3 + v14 + v15
vc,9 = 2502 + 0.5(50) + 0 + 0 = 150 veh/h
cp,9 = vc,9e−vc,9tc,9 /3,600
1− e−vc,9tf,9 /3,600
cp,9 = 150e−150(7.1)/3,600
1− e−150(3.4)/3,600 =845 veh/h
pp,9 = 1.0 – fp = 1.0 – 0.000 = 1.000
cm,9 = cp,9 pp,9 = (845)(1.000) = 845 veh/h
p0,9 = 1 – v9
cm,9 = 1 –
55845 = 0.935
6. Movement capacities, cm,x, forminor TH and minor LTmovements, accounting forimpedance and two-stage gapprocess (use Equations 17-32,17-33, or 17-7 and Exhibit 17-4).
Worksheets 7a and 7bvc,I,8 = 341 veh/h
vc,II,8 = 532 veh/h
vc,8 = 873 veh/h
Single Stagecm,8 = cp,8 f8 = 273(0.917) = 250 veh/h
Two-Stage
cT =α
ym+1 −1y(ym −1)...[ ]
cT =0.949
1.8082+1 −11.808(1.8082 −1)...[ ] =390 veh/h
Highway Capacity Manual 2000
Chapter 17 - Unsignalized Intersections 17-68Example Problems
7. Shared-lane capacity (useEquation 17-15).
Worksheet 8
cSH =vy
y∑
vy
cmy∑
cSH (NB) = 44 +132 + 5544370
+ 132390
+ 55845
=442 veh/h
8. Flared approach capacity (useEquations 17-36 and 17-38).
Worksheet 9 - Movement 7
d = 3,600cm,x
+ 900T ...[ ] + 5
d = 3,600369
+ 900 0.25( ) ...[ ] + 5 = 16.070 s
Qsep =d7v7
3,600=
16.0( ) 44( )3,600
= 0.196
cact (NB) = csepi∑ − cSH
nnMax
+ cSH
cact = (1,605 – 442) 12 + 442 = 1,024 veh/h
9. Control delay and LOS (useEquation 17-38 and Exhibit17-2).
Worksheet 10
dNB = 3,600cm,x
+ 900T[... ] + 5
dNB = 3,6001,024
+ 900 0.05( )[... ] + 5 = 9.5 s
LOS A10. Skip Worksheet 11. No Rank 1 vehicle delay
Highway Capacity Manual 2000
17-69 Chapter 17 - Unsignalized IntersectionsExample Problems
Example Problem 3
STOP
STOP
v1v2v3
v12
v7
v10
v9
v13
v14v15
v16v6
v4S2
S5
v11
v8
v5
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 1
Worksheet 2
Vehicle Volumes and Adjustments
Pedestrian Volumes and Adjustments
Vehicle Volumes and Adjustments
Movement 1 2 3 4 5 6 7 8 9 10 11 12
Volume (veh/h)
Peak-hour factor, PHF
Hourly flow rate (veh/h)
Proportion of heavy vehicles, PHV
Movement 13 14 15 16
Flow, Vx (ped/h)
Lane width, w (m)
Walking speed,1 Sp (m/s)
Percent blockage, fp (Equation 17-11)
1. Default walking speed = 1.2 m/s
General Information Site Information
Analyst ______________________ Intersection ________________________Agency or Company ______________________ Jurisdiction ________________________Date Performed ______________________ Analysis Year ________________________Analysis Time Period ______________________
Geometrics and Movements
Length of study period = _____ h grade = ______
grade = ______
grade = ______
grade = ______
Show NorthStre
et
Street
JME Walnut/ElmCEI Latah County5/7/99 1999AM Peak
28 110
132 55
33
250
50
33 250 50 66 300 100 44 132 55 11 110 28
1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
33 250 50 66 300 100 44 132 55 11 110 28
0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
0 0 0 0
Walnut
Elm
0%
0%
0%
0%0.25
100300
6644
11
Chapter 17 - Unsignalized Intersections 17-70Example Problems
Highway Capacity Manual 2000
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 3
Movement 9 " Yes " No Storage space, n ________________(number of vehicles)
Movement 12 " Yes " No Storage space, n ________________(number of vehicles)
Type
Movements 7 and 8 " Yes _____ " No Storage space, m ________________(number of vehicles)
Movements 10 and 11 " Yes _____ " No Storage space, m ________________(number of vehicles)
* Includes raised or striped median (RM), or two-way left-turn lane (TWLTL)
Lane Designation
Movements Lane 1 Lane 2 Lane 3 Grade, G Right TurnChannelized?
1, 2, 3
4, 5, 6
7, 8, 9
10, 11, 12
Flared Minor-Street Approach
Median Storage*
Computing Delay to Major-Street Vehicles
Upstream Signals
Data for Computing Effect of Delay to Major-Street Vehicles S2 Approach S5 Approach
Shared-lane volume, major-street through vehicles, vi1, blocked by LT
Shared-lane volume, major-street right-turn vehicles, vi2, blocked by LT
Saturation flow rate, major-street through vehicles, si1
Saturation flow rate, major-street right-turn vehicles, si2
Number of major-street through lanes
Length of study period, T (h)
Movements Distance to Prog Speed, Cycle Green Time, Arrival Saturation Flow Progressed Flow,Signal, D (m) Sprog (km/h) Length, C (s) geff (s) Type Rate, s (veh/h) Vprog (veh/h)
protected LT 3
TH
protected LT 3
TH
S2
S5
General Information
Project Description _________________________________________________________________________________
Example Problem 3
1 2 2, 3 0 N
4 5 5, 6 0 N
7, 8, 9 0 N
10, 11, 12 0 N
X
X
X
X
1
1
2
2
RM
RM
Example Problem 3
2.2 2.2 3.3 3.3 4.0 4.0 3.5 3.51.0 1.0 1.0 1.0 1.0 1.0 1.0 1.00.10 0.10 0.10 0.10 0.10 0.10 0.10 0.102.300 2.300 3.400 3.400 4.100 4.100 3.600 3.600
Highway Capacity Manual 2000
17-71 Chapter 17 - Unsignalized IntersectionsExample Problems
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 4
Critical Gap and Follow-Up Time
tc = tc,base + tc,HV PHV + tc,G G - tc,T - t3,LT
tf = tf,base + tf,HV PHV
tc,T
tc (Equation 17-1)
Worksheet 5a
Time to Clear Standing Queue (Computation 1)
Movement 2 Movement 5vT,prog vL,prot vT,prog vL,prot
Effective green, geff (s)
Cycle length, C (s)
Saturation flow rate, s (veh/h)
Arrival type 3 3
vprog (veh/h)
Rp (from Chapter 16) 1.00 1.00
Proportion of vehicles arrivingon green, P (Equation 17-17)
gq1 (Equation 17-18)
gq2 (Equation 17-19)
gq (Equation 17-20)
General Information
Project Description _________________________________________________________________________________
Major LT Minor RT Minor TH Minor LTMovement 1 4 9 12 8 11 7 10
tc,base (Exhibit 17-5)
tc,HV
PHV (from Worksheet 2)
tc,G - - 0.1 0.1 0.2 0.2 0.2 0.2
G (from Worksheet 3)t3,LT
single stage
two stage
single stage
two stage
Example Problem 3
Major LT Minor RT Minor TH Minor LT
Movement 1 4 9 12 8 11 7 10
tf,base (Exhibit 17-5)
tf,HV
PHV (from Worksheet 2)
tf (Equation 17-2)
4.1 4.1 6.9 6.9 6.5 6.5 7.5 7.52.0 2.0 2.0 2.0 2.0 2.0 2.0 2.00.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
0 0 0 0 0 0 0 00.0 0.0 0.0 0.0 0.0 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 0.0 0 .0- - - - 1.0 1.0 1.0 1.04.300 4.300 7.100 7.100 6.700 6.700 7.700 7.700- - - - 5.700 5.700 6.700 6.700
Example Problem 3
Chapter 17 - Unsignalized Intersections 17-72Example Problems
Highway Capacity Manual 2000
7
7
7
10
10
10
0,4 0,1
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 6
Step 1: RT from Minor Street v9 v12
Conflicting flows (Exhibit 17-4) vc,9 = vc,12 =
Potential capacity (Equation 17-3 or 17-29) cp,9 = cp,12 =
Ped impedance factor (Equation 17-12) pp,9 = pp,12 =
Movement capacity (Equation 17-4) cm,9 = cp,9 pp,9 = cm,12 = cp,12 pp,12 =
Prob of queue-free state (Equation 17-5) p0,9 = p0,12 =
Step 2: LT from Major Street v4 v1
Conflicting flows (Exhibit 17-4) vc,4 = vc,1 =
Potential capacity (Equation 17-3 or 17-29) cp,4 = cp,1 =
Ped impedance factor (Equation 17-12) pp,4 = pp,1 =
Movement capacity (Equation (17-4) cm,4 = cp,4 pp,4 = cm,1 = cp,1 pp,1 =
Prob of queue-free state (Equation 17-5) p0,4 = p0,1 =
Major left shared lane prob of queue-free state (Equation 17-16) p* = p* =
Step 3: TH from Minor Street (4-leg intersections only) v8 v11
Conflicting flows (Exhibit 17-4) vc,8 = vc,11 =
Potential capacity (Equation 17-3 or 17-29) cp,8 = cp,11 =
Ped impedance factor (Equation 17-12) pp,8 = pp,11 =
Capacity adjustment factor due to impeding movement f8 = p0,4 p0,1 pp,8 = f11 = p0,4 p0,1 pp,11 =(shared lane use p*) (Equation 17-13)
Movement capacity (Equation 17-7) cm,8 = cp,8 f8 = cm,11 = cp,11 f11 =
Prob of queue-free state p0,8 = p0,11 =
Step 4: LT from Minor Street (4-leg intersections only) v7 v10
Conflicting flows (Exhibit 17-4) vc,7 = vc,10 =
Potential capacity (Equation 17-3 or 17-29) cp,7 = cp,10 =
Ped impedance factor (Equation 17-12) pp,7 = pp,10 =
Major left, minor through impedance factor p'' = p0,11 f11 = p'' = p0,8 f8 =
Major left, minor through adjusted impedance factor p' = p'
=(Equation 17-8)
Capacity adjustment factor due to impeding movements f7 = p' p0,12 pp,7 = f10 = p' p0,9 pp,10 =
(Equation 17-14)
Movement capacity (Equation 17-10) cm,7 = f7 cp,7 = cm,10 = f10 cp,10 =
Step 5: LT from Minor Street (T-intersections only) v7 v10
Conflicting flows (Exhibit 17-4) vc,7 = vc,10 =
Potential capacity (Equation 17-3 or 17-29) cp,7 = cp,10 =
Ped impedance factor (Equation 17-12) pp,7 = pp,10 =
Capacity adjustment factor due to impeding movement f7 = p0,4 p0,1 pp,7 = f10 = p0,4 p0,1 pp,10 =(shared lane use p*) (Equation 17-13)
Movement capacity (Equation 17-7) cm,7 = cp,7 f7 = cm,10 = cp,10 f10 =
Impedance and Capacity Calculation
General Information
Project Description _________________________________________________________________________________
Notes
1. For 4-leg intersections use Steps 1, 2, 3, and 4.2. For T-intersections use Steps 1, 2, and 5.
Example Problem 3
150 200845 7831.000 1.000
845 7830.935 0.964
300 4001202 11001.000 1.000
1202 11000.945 0.970
Example Problem 3
Highway Capacity Manual 2000
17-73 Chapter 17 - Unsignalized IntersectionsExample Problems
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 7a
Effect of Two-Stage Gap Acceptance
Step 3: TH from Minor Street v8 v11
Part I - First Stage
Conflicting flows (Exhibit 17-4) vc,I,8 = vc,I,11 =
Potential capacity (Equation 17-3 or 17-29) cp,I,8 = cp,I,11 =
Ped impedance factor (Equation 17-12) pp,I,8 = pp,I,11 =
Capacity adjustment factor due to impeding movement fI,8 = p0,1 pp,I,8 = fI,11 = p0,4 pp,I,11 = (shared lane use p*) (Equation 17-6 or 17-13)
Movement capacity (Equation 17-7) cm,I,8 = cp,I,8 fI,8 = cm,I,11 = cp,I,11 fI,11 =
Prob of queue-free state (Equation 17-5) p0,I,8 = p0,I,11 =
Part II - Second Stage
Conflicting flows (Exhibit 17-4) vc,II,8 = vc,II,11 =
Potential capacity (Equation 17-3 or 17-29) cp,II,8 = cp,II,11 =
Ped impedance factor (Equation 17-12) pp,II,8 = pp,II,11 =
Capacity adjustment factor due to impeding movement fII,8 = p0,4 pp,II,8 = fII,11 = p0,1 pp,II,11 = (shared lane use p*) (Equation 17-6 or 17-13)
Movement capacity (Equation 17-7) cm,II,8 = cp,II,8 fII,8 = cm,II,11 = cp,II,11 fII,11 =
Prob of queue-free state (Equation 17-5) p0,II,8 = p0,II,11 =
Part III - Single Stage
Conflicting flows (Exhibit 17-4) vc,8 = vc,11 =
Potential capacity (Equation 17-3 or 17-29) cp,8 = cp,11 =
Ped impedance factor (Equation 17-12) pp,8 = pp,11 =
Capacity adjustment factor due to impeding movement f8 = p0,4 p0,1 pp,8 = f11 = p0,4 p0,1 pp,11 =(shared lane use p*) (Equation 17-13 or 17-16)
Movement capacity (Equation 17-7) cm,8 = cp,8 f8 = cm,11 = cp,11 f11 =
Result for Two-Stage Process
a (Equation 17-30) a = a =
y (Equation 17-31) y = y =
cT (Equation 17-32 or 17-33) cT = cT =
Prob of queue-free state (Equation 17-5) p0,8 = p0,11 =
General Information
Project Description _________________________________________________________________________________
Example Problem 3
341 482
618 532
1.000 1.000
0.970 0.945
599 503
0.780 0.781
532 366
504 601
1 .000 1.000
0.945 0.970
476 583
0.723 0.811
873 848
273 283
1.000 1.000
0.917 0.917
250 260
0.949 0.949
1.808 0.946
390 405
0.662 0.728
Example Problem 3
Chapter 17 - Unsignalized Intersections 17-74Example Problems
Highway Capacity Manual 2000
7
7
7
10
10
10
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 7b
Effect of Two-Stage Gap Acceptance
Step 4: LT from Minor Street v7 v10
Part I - First Stage
Conflicting flows (Exhibit 17-4) vc,I,7 = vc,I,10 =
Potential capacity (Equation 17-3 or 17-29) cp,I,7 = cp,I,10 =
Ped impedance factor (Equation 17-12) pp,I,7 = pp,I,10 =
Capacity adjustment factor due to impeding movements fI,7 = p0,1 pp,I,7 = fI,10 = p0,4 pp,I,10 =
Movement capacity (Equation 17-7) cm,I,7 = fI,7 cp,I,7 = cm,I,10 = fI,10 cp,I,10 =
Part II - Second Stage
Conflicting flows (Exhibit 17-4) vc,II,7 = vc,II,10 =
Potential capacity (Equation 17-3 or 17-29) cp,II,7 = cp,II,10 =
Ped impedance factor (Equation 17-12) pp,II,7 = pp,II,10 =
Capacity adjustment factor due to impeding movements fII,7 = p0,4 p0,I,11 p0,12 pp,II,7 = fII,10 = p0,1 p0,I,8 p0,9 pp,II,10 =
Movement capacity (Equation 17-7) cm,II,7 = fII,7 cp,II,7 = cm,II,10 = fII,10 cp,II,10 =
Part III - Single-Stage
Conflicting flows (Exhibit 17-4) vc,7 = vc,10 =
Potential capacity (Equation 17-3 or 17-29) cp,7 = cp,10 =
Ped impedance factor (Equation 17-12) pp,7 = pp,10 =
Major left, minor through impedance factor p" = p0,11 f11 = p" = p0,8 f8 =
Major left, minor through adjusted impedance factor p' = p' =(Equation 17-8)
Capacity adjustment factor due to impeding movements f7 = p' p0,12 pp,7 = f10 = p' p0,9 pp,10 =(Equation 17-9 or 17-14)
Movement capacity (Equation 17-7) cm,7 = f7 cp,7 = cm,10 = f10 cp,10 =
Result for Two-Stage Process
a (Equation 17-30) a = a =
y (Equation 17-31) y = y =
cT (Equation 17-32 or 17-33) cT = cT =
General Information
Project Description _________________________________________________________________________________
Example Problem 3
341 482
626 514
1.000 1.000
0.970 0.945
607 486
337 257
629 703
1.000 1.000
0.711 0.707
447 497
678 739
323 291
1.000 1.000
0.668 0.607
0.742 0.694
0.715 0.649
231 189
0.949 0.949
2.055 1.227
369 347
Example Problem 3
Highway Capacity Manual 2000
17-75 Chapter 17 - Unsignalized IntersectionsExample Problems
(Equation 17-15)vy
cm,y
cSH =
( )
∑vy
∑
y
y
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 8
Movement v (veh/h) cm (veh/h) cSH (veh/h)
7
8
9
10
11
12
Worksheet 9
Movement 7 Movement 8 Movement 9 Movement 10 Movement 11 Movement 12
csep (from Worksheet 6 or 7)
Volume (from Worksheet 2)
Delay (Equation 17-38)
Qsep (Equation 17-34)
Qsep + 1
Round (Qsep + 1)
nmax (Equation 17-35)
cSH
csep
n
cact (Equation 17-36)
Effect of Flared Minor-Street Approaches
Shared-Lane Capacity
General Information
Project Description _________________________________________________________________________________
Example Problem 3
44 369
132 390 442
55 845
11 347
110 405 439
28 783
369 390 845 347 405 783
44 132 55 11 110 28
16.070 18.881 9.557 15.714 17.171 9.768
0.196 0.692 0.146 0.048 0.525 0.076
1.196 1.692 1.146 1.048 1.525 1.076
1 2 1 1 2 1
2 2
442 439
1604 1535
1 1
1023 987
Example Problem 3
Chapter 17 - Unsignalized Intersections 17-76Example Problems
Highway Capacity Manual 2000
TWSC - UNSIGNALIZED INTERSECTIONS WORKSHEET
Worksheet 10
Delay to Rank 1 Vehicles
Worksheet 11
Control Delay, Queue Length, Level of Service
S2 Approach S5 Approach
p0,j (Equation 17-5)
vi1, volume for Stream 2 or 5
vi2, volume for Stream 3 or 6
si1, saturation flow rate for Stream 2 or 5
si2, saturation flow rate for Stream 3 or 6
p0,j (Equation 17-16)
dmajor left, delay for Stream 1 or 4
N, number of major-street through lanes
dRank 1, delay for Stream 2 or 5 (Equation 17-39)
Lane v (veh/h) cm (veh/h) v/c Queue Length Control Delay LOS Delay and LOS(Equation 17-37) (Equation 17-38) (Exhibit 17-2)
1
2
3
1
2
3
Movement v (veh/h) cm (veh/h) v/c Queue Length Control Delay LOS(Equation 17-37) (Equation 17-38) (Exhibit 17-2)
1
4
General Information
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Example Problem 3
*
121110
121110
121110
987
987
987
p0,1 = p0,4 =
p* = p* =0, 1 0, 4
Example Problem 3
231 1024 0.226 < 1 9.5 A 9.5A
149 987 0.151 < 1 9.3 A 9.3A
X X X
33 1100 0.030 < 1 8.4 A
66 1216 0.055 < 1 8.2 A
X X X