Question

calculation steps of level of service for multi lane ways

Answer 1

For multilane highways, these are the steps to determine LOS and Density

1) Calculate HEAVY VEHICLE FACTOR

This is calculated using the formula

fHV and it is calculated using the formula

where ET, ER are the E values for trucks+buses and for RV's - these vary according to terrain ie level, rolling, mountaneous

PT and PR are the percentage of (trucks + buses) and RV's expressed in decimals

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2) Given the peak hour flow V in veh/hour, calculate the 15 minute peak period pc/hr/ln as follows

So Calculate vp based on the formula

where V = flow in veh/hour, PHF = peak hour factor, N = number of lanes in one direction, fHV = heavy vehicle factor

fp = driver familiarity factor = 1 if all drivers are commuters and very familiar with the route, otherwise it is some value less than 1

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3) Calculate measured FFS

Measured FFS = BFFS - fLW - fLC -fN -fID

where

DO all calcs in mph and then convert back to kmph at the last

BFFS = base free flow speed

fLW = adjustment for lane width (check from HCM tables)

fLC = adjustment for right-shoulder lateral clearance (check from HCM tables)

fN = adjusment for number of lanes (check from HCM tables)

fID = adjustment for interchange density (check from HCM tables)

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4) Density = vp/measured FFS

compute this in pc/km/ln.

Then look at LOS thresholds for density and find the LOS