Bus simulation in excel, exponential distribution departure

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SUMMARY

The discussion focuses on simulating bus departures between points A and B using Excel, specifically employing the negative exponential distribution with a parameter of 10 trips per hour. The user is attempting to calculate the average headway over a 5-hour simulation. Key insights include the correct interpretation of the parameter λ, which should be set to 1/6 to reflect the mean headway of 6 minutes. Additionally, the use of the inverse transform method T = -ln(U)/λ is recommended for generating exponentially distributed headways.

PREREQUISITES
  • Understanding of negative exponential distribution and its parameters
  • Familiarity with Excel functions such as RAND() and RANDBETWEEN()
  • Knowledge of the inverse transform sampling method
  • Basic concepts of Poisson distribution for discrete events
NEXT STEPS
  • Implement the inverse transform method T = -ln(U)/λ in Excel for generating random headways
  • Explore how to use Poisson distribution to model bus arrivals over a fixed time period
  • Learn about Excel's statistical functions for simulating random variables
  • Research best practices for visualizing simulation results in Excel
USEFUL FOR

This discussion is beneficial for students and professionals involved in operations research, transportation modeling, and anyone interested in simulating stochastic processes using Excel.

AGS
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Homework Statement



The bus service operates between points A and B. The buses depart from the terminal station A with headways that follow the negative exponentioal distributiona with parameter 10 trips per hour.
Assume that the characteristics of the system remain the same over time (not time dependent). Run simulation for 5 hours and find the average headway in each of the 5 hours.

So what I am having trouble with is the exponential distributed departure for each bus.

Homework Equations


no eq. given


The Attempt at a Solution


I think that the formula to work with is
f(x)=lamda*exp(-lamda*x)
Im little confused if lamda is 10 or 10/60=1/6 but it 1/6 makes more sense to me since I think the mean (mui=expected value) headway is 6 minutes and lamda=1/mui.
Im using excel and used the randbetween(0,35) to give me random x and than I plotted it and got a plot that looked ok. I also tried with lamda=10 but than I used rand() that gives random number between (0,1).
My problem is that I don´t know how to use this information to get random exponential distrebuted headways for each bus!
Should I maby use the inverse? T=-lnU/lamda (use rand() to get U)
 
Last edited:
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Hey,

Given that you have time constraint, parameter \lambda and that that the bus journeys are discrete I think u will have to use Poisson distribution to generate the probabilities, however, You must not forget to multiply the parameter by 5 as your simulation is going to take 5 hours. Once this is completed one can generate probabilities for 5 hour bus journeys and create a rule for simulation.
 

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