MTO TRAFFIC MODELMTO TRAFFIC MODEL

The following presentation contains references to The following presentation contains references to Figures 6.02 Figures 6.02 andand

6.036.03, , Tables 6.01Tables 6.01 and and 6.046.04, all of which are posted under , all of which are posted under

subsection 2.6 of the course notes on the instructor’s website. subsection 2.6 of the course notes on the instructor’s website.

Viewer discretion is advised as some scenes contain material of a Viewer discretion is advised as some scenes contain material of a

graphic, tabular and mathematical nature and are intended for graphic, tabular and mathematical nature and are intended for

mature audiences.mature audiences.

MTO TRAFFIC MODELMTO TRAFFIC MODELWhat does it do?What does it do?

Enables you to estimate the number of Enables you to estimate the number of passes of a standard unit (ESAL) over a passes of a standard unit (ESAL) over a

pavement during a specific design period.pavement during a specific design period.

What information do you need?What information do you need?

Analysis Period, AAnalysis Period, App

AADT in first year of AAADT in first year of App

Annual Percent Traffic Growth RateAnnual Percent Traffic Growth Rate

Number of Traffic Lanes & DirectionsNumber of Traffic Lanes & Directions

Percent Trucks in Initial & Final Year of APercent Trucks in Initial & Final Year of App

Total ESAL’s, NTotal ESAL’s, Nff Over Analysis Over Analysis

PeriodPeriod The MTO uses a The MTO uses a trapezoidaltrapezoidal representation representation of the total accumulated ESAL’s over the of the total accumulated ESAL’s over the

analysis periodanalysis period

ESA

L’s/

day

Time

Initial Year Final YearMiddle Year

Final ESAL’s/day

Initial ESAL’s/day

Average ESAL’s/day or DTN

Nf is the area of the trapezoid = number of days

in Ap x DTN

Analysis Period, Ap

Accumulated ESAL’s, NAccumulated ESAL’s, N

The MTO uses a parabolic model to The MTO uses a parabolic model to determine the accumulated ESAL’s after Y determine the accumulated ESAL’s after Y

years of the analysis periodyears of the analysis period

The EquationsThe Equations

2

5.05.0 ffffiiiipf

TFLDFTAADTTFLDFTAADTdaysAN

DTNdaysAN pf

Factor days out of equation 2

EXAMPLEXAMPLEE

The initial The initial AADTAADT for a for a 4-lane4-lane road road is is 12500 vpd12500 vpd and is expected to and is expected to grow over the next grow over the next 20 years20 years at the at the rate of rate of 3.5%/year3.5%/year. If the percent . If the percent trucks is expected to increase from trucks is expected to increase from 10%10% initially to initially to 15%15% at the end of at the end of the analysis period. Find the the analysis period. Find the accumulated ESAL’s after accumulated ESAL’s after 1212 yearsyears of traffic.of traffic.

OK, now pull out your copy of Table OK, now pull out your copy of Table 6.046.04Parameter/Parameter/

Calculation Calculation DescriptionDescription

Parameter Parameter DesignatioDesignatio

nnAnalysis PeriodAnalysis Period AAPP

Traffic Growth Rate (%/year)Traffic Growth Rate (%/year) TGRTGR

Number of Traffic LanesNumber of Traffic Lanes LanesLanesAverage Annual Daily Traffic, two Average Annual Daily Traffic, two

directionsdirections AADTAADT

Directional SplitDirectional Split DFDF

Truck Fraction of Total TrafficTruck Fraction of Total Traffic TT

Lane Distribution Factor (Table 6.01)Lane Distribution Factor (Table 6.01) LDFLDF

Truck Factor: ESAL's/truck (Figure 6.03)Truck Factor: ESAL's/truck (Figure 6.03) TFTFDaily Total ESAL's/dayDaily Total ESAL's/day

= AADT x DF x T x LDF x TF = AADT x DF x T x LDF x TF ESAL/dayESAL/day

InitialInitial FinalFinal

2020

44

3.5%3.5%

44

12,50012,500 24,872.3624,872.36

0.50.5 0.50.5

0.100.10 0.150.15

0.800.80 0.750.75

0.770.77 0.970.97

385385 1357.0981357.098

? 36.872,24100

5.31500,12

20

fAADT

? ?

? ?

TABLE 6.01

MTO LANE DISTRIBUTION FACTORS

(After: "Pavement Design and Rehabilitation Manual", 1990)

Lane DistributionHighway Type AADT (vpd) Factor, LDF

2 lanes All 1.00

< 5000 0.85

5000 - 15000 0.804 lanes

15000 - 25000 0.75

> 25000 0.70

< 15000 0.60

15000 - 25000 0.556 lanes

25000 - 40000 0.50

> 40000 0.45

FIGURE 6.03b - MTO TRUCK FACTORS: 4-LANE HIGHWAYS

0.0

0.5

1.0

1.5

2000 3000 4000 5000 6000 7000 8000

Traffic/Lane (= AADT/4 for 4-Lane Highways)

Truc

k Fa

ctor

, TF

40% HCT

30% HCT

20% HCT

10% HCT

31254

500,12/ laneAADTi

0.77

09.62184

36.872,24/ laneAADTi

0.97

? ?

38577.080.010.05.0500,12/ dayESALi 098.135797.075.015.05.036.872,24/ dayESAL f

Bring it on home!Bring it on home!

Parameter/Parameter/Calculation Calculation DescriptionDescription

Parameter Parameter DesignatioDesignatio

nnDaily Total ESAL's/day Daily Total ESAL's/day

= AADT x DF x T x LDF x TF= AADT x DF x T x LDF x TF ESAL/dayESAL/day

Days per year for truck trafficDays per year for truck traffic daysdaysDesign Traffic Number for Design Period Design Traffic Number for Design Period = =

[(ESAL/day)[(ESAL/day)ii + (ESAL/day) + (ESAL/day)ff]/2]/2 DTNDTNTotal ESAL's over Analysis Period, Ap Total ESAL's over Analysis Period, Ap

= DTN x Days x Ap = DTN x Days x Ap NNff

Design Period, yearsDesign Period, years YYTotal ESAL's over Design Period, Total ESAL's over Design Period,

Equation 1, Figure 6.02Equation 1, Figure 6.02 NN

InitialInitial FinalFinal

871.0490929871.0490929

300300

385385 1357.0981357.098

?

0490929.871

2

098.1357385

DTN

?

?

295,226,555735706.294,226,5300200490929.871 fN

2

36.872,24500,1220

500,1236.872,24

36.872,24500,12

500,122

20

295,226,5YYN

5,226,2955,226,295

1212

2,720,5292,720,529

2016552822.0668943558.075.314,261 YYN 249657.325,4819.804,174 YYN

529,720,21249657.325,412819.804,174 2 N