# Vehicles - Traffic Flow and Density

## Vehicles flow and density in highway design

### Vehicle Traffic Flow

The vehicle traffic flow on a road can be expressed

*q = n 3600 / t (1)*

*where *

*q = vehicle flow (no. vehicles per hour)*

*n = no. vehicles passing in t seconds*

*t = time for passing vehicles (s)*

#### Example - Vehicle Traffic Flow

If *1000* vehicles passes in *2 hours (7200 s)* - the flow can be calculated

*q = 1000 3600 / 7200 (s)*

* = 500 vehicles per hour*

### Vehicle Density

Vehicle density can be expressed as

*k = n 5280 / l (2)*

*where *

*k = vehicle density (vehicles per mile)*

*n = no. of vehicles occupying a length l of the road *

*l = the length of road occupied by the vehicles (ft)*

*(2)* expressed in km

*k = n 1000 / l (2b)*

*where *

*k = vehicles per km*

*n = no. of vehicles occupying a length l of the road *

*l = the length of road occupied by the vehicles (m)*

## Related Topics

## Related Documents

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- en: vehicle flow density highway design