Design Hour Factor (K) Calculation & peak hour traffic conversion ADT.

[RizAhmed]

Greetings to all members,

I have pleasure to join the forum of traffic engineers.
A little intro of myself. My name is Rizwan and I am working in UAE in a consultancy as traffic engineer with 3 years experience. We won a project of design of an interchage (currently in concept design stage) and I am working on traffic study of the same. In this regard, i have following questions. I will appreciate the suggestions from all. Thanking all in advance.

Q-1: Any standard process to calculate Design Hour Factor (K) from existing traffic count data?

Q-2:I have a peak hour traffic volume of 12000 veh/lane on a freeway facililty in particular direction.Total lanes are 6. K factor is 0.082 (calculated using traffic volume in both directions)
How can we convert the peak hour traffic volume to daily 24 hour traffic volume? If I use the formula DDHV=ADT*K for ADT calcualtion, the resultant value of ADT looks very high.

I have attached an excel file for K-factors that I calculated from traffic count survey data for AM LT & PM peaks at a certain location on highway.

 

[RizAhmed]

the peak hour traffic volume is 2000 veh/lane in Q-2, by mistake i mentioned 12000 veh/lane.

 

[Debaser]

I believe that, very, very, very, very roughly, the peak hour (as opposed to 30th highest hour, etc.) is about 10% of the daily flow.

6 x 2000 = 12,000 Total PHF in 6 lanes
10 x 12,000 = 120,000 AADT

So in terms of order of magnitude I think you're OK.

The two thousand vehicles per lane in the peak hour is a fairly high starting point; in the UK that's approaching the figure for the maximum sustainable hourly throughput according to TA46/97 (and assuming 15% HGVs).

http://www.dft.gov.uk/ha/standards/dmrb/vol5/section1/ta4697.pdf

 

[ACtrafficengr]

The rule of thumb for this area is peak hour volume is usually close to 11% of the daily traffic in urban areas, 15% in rural areas.

Your mileage (kilometerage?) may vary.

Maybe the tyranny of Murphy is the penalty for hubris. -

http://xkcd.com/319/

 

[francesca]

In Dubai I would expect a more attenuated peak hour. The best way to get meaningful data is to send someone to the intersection and do a 12 (or 15) hour count, but this probably isn't the time of year for that... especially not with Ramadan starting when your peak hour will probably be closer to midnight.