CEE 123 Transport Systems 3: Planning & Forecasting
Winter 2019: Michael G. Mc Nally (mmcnally-at-uci-dot-edu) [17070]
Homework #6 -- Trip Distribution Modeling [Due: Friday 19 May 2021]

The following problems deal with a hypothetical, 4-zone region (this data will be used in a subsequent trip assignment homework). Table 1 summarizes surveyed activity system and trip generation data (productions and attractions) for 2020, and estimates of activity system variables for 2030. 

 Table 1. Base and Future HBW Trips and Demographic Data Summary
-----------------------------------------------------------------
        HBW        HH(i)      C(i)       W(i)       E(j)    I(i)
     P(i) A(j)  Households    Cars      Workers     Empl.   Inc.
Zone  '20  '20  ---------- ---------- ---------- ---------- -----
                 '20  '30   '20  '30   '20  '30   '20  '30  both
-----------------------------------------------------------------
  1   825  710   321  330   447  460   390  395   300  300   Low
  2   775  800   402  470   360  420   345  480   360  450   Med
  3   910  970   330  300   396  375   582  570   600  690  High
  4   865  895   375  420   450  465   399  450   456  455   Med
-----------------------------------------------------------------
 Tot 3375 3375  1428 1520  1653 1720  1716 1895  1716 1895   N/A
-----------------------------------------------------------------

Problem 1. Trip Generation [10 points]
Household HBW trip production and attraction models for the region as a whole have been estimated and found to be significant.

Pi = 34.8 + 0.59 HHi + 0.80 Ci + 0.63 Wi

Aj = 485.1 + 0.84 Ej

  1. Using the base data, apply the models and estimate a goodness-of-fit measure for each model. For example, compute the root mean square error, RMSE=sqrt[(1/n)Σ(est-obs)^2]. Comment on the fit.

  2. Use the demographic forecasts provided to predict and tabulate future trip ends for the production and attraction models. These estimates will be used in the trip distribution forecast.

Problem 2. Trip Distribution: Calibration (20 points)
By hand, calibrate a singly-constrained trip distribution model for the base year data. Show ALL calculations for three iterations. Does the model converge? Utilize attraction balancing at each iteration. Use 5-minute time categories. 

Table 2. Base Travel Time and HBW Trip Distribution Matrix (2010)
---------------------------------------------------------------
 From\To   1   2   3   4    From\To    1    2    3    4  P(i)
---------------------------------------------------------------
     1     5  16  13  18        1    250  125  375   75   825
     2    16   7  20  12        2    100  400   50  225   775
     3    13  20   2   9        3    205   60  225  420   910
     4    18  12   9   3        4    155  215  320  175   865
---------------------------------------------------------------
                              A(j)   710  800  970  895  3375
---------------------------------------------------------------

Problem 3. Trip Distribution: Application (10 points)
In response to identified problems in the base network and to anticipated traffic volumes from future growth, a network infrastructure project has been planned that would change base travel times between some zones. In general, infrastructure would be improved around Zone 1 (low income with little projected growth) while identified problems in Zone 4 would not be addressed by the plan.

Forecast the corresponding future total trip matrix using the trip generation forecast from Problem 1, the calibrated model from Problem 2, and the original (A0) and new (A1) skim trees given in Table 3. Utilize column/row factoring on the final trip table. 

Table 3. Base and Future Transportation System Skims
------------------------------------------------------
 BASE      Travel Times     FUTURE     Travel Times
         ----------------           -----------------
 From\To   1   2   3   4    From\To    1   2   3   4
------------------------------------------------------
     1     5  16  13  18         1     6  14  11  14
     2    16   7  20  12         2    14   8  17  15
     3    13  20   2   9         3    11  17   3  11
     4    18  12   9   3         4    14  15  11   5
------------------------------------------------------

Problem 4. Trip Distribution: Performance (10 points)
Summary statistics help describe the overall flow pattern at the end of trip distribution. Using skim tree times for the base and future networks, and the base and estimated future trip distribution matrices, compute the average trip travel times for 2020 and 2030. Tabulate total trips, total time, and average travel times for each year.

Problem 5. Travel Surveys (20 points)
The spreadsheet provides 2020 household socio-economic and travel diary data for a sub-sample of Miasma Beach households. Use only households 4 through 6 in this exercise.

  1. Calculate the trip travel time, activity duration, and trip purpose classification (HBW, HBO, or NHB) for each trip and append to the table. Compute the mean travel time by mode and mean activity duration by purpose. Submit a hardcopy (e-copy optional) of the updated spreadsheet.
  2. Plot the travel patterns on a Miasma Beach network map. Label each trip end as a production (P) or attraction (A) and label the trip type (HBW, HBO, NHB). Use color and/or line types to distinguish individuals and/or trip types. You may need to plot households on separate maps.
  3. Calculate the associated OD trip table and the PA trip table.
Note: The results of this assignment will be needed in Homework #7.
Last Updated: 10 May 2021