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TDM Calibration & 2050 Population Forecast

Traffic Modeling

The base year for the Metropolitan Transportation Plan (MTP) will be 2020. Assuming that 2020 Census data and traffic counts will be available by Spring of 2022, the Census data needs to be distributed to Traffic Analysis Zones (TAZs) and the APO’s regional Travel Demand Model (TDM) needs to be recalibrated to the new base year. But, before the TDM can be recalibrated, the APO desires that the outcomes of two previous projects be fully incorporated into the TDM: 1) the Travel Demand Model Improvement effort in 2020 and 2) the 2021 Household Travel Survey. Both of those efforts resulted in outputs and recommendations that need to be implemented into the TDM program files. Also, since 2050 is the horizon planning-year for the next MTP, reasonable estimates of 2050 population, jobs, and other socio-economic data need to be completed in cooperation with the APO’s member jurisdictions and distributed to the TAZs. Finally, using the 2050 socio-economic data and the 2020 roadway network (provided by APO staff), a 2050 no-build model scenario needs to be completed in order to highlight future areas of concern if no additional investments were made in the roadway network.

OPTIONAL: If consultants can complete the tasks above, but additional budget remains, the APO is also interested in scenario model runs that attempt to address problem areas highlighted in the 2050 “no build” model output. For example, we would be interested in seeing a 2050 “no-build + beltway” scenario to estimate the impact the beltway corridor alone would have on traffic operations. Another example would be if the 2050 “no build” model shows deficient operations on Corridor X, what happens if Corridor X is widened? Does it solve the problem? Does it push the problem to another corridor? Is it even possible to widen the corridor sufficiently to alleviate the problem?

Previous Relevant Work

2017 – Population Forecast for 2045 Memo

2019 – Travel Demand Model Calibration Report

2020 – Model Improvement Tech Memos

2021 – Household Travel Survey Documents



Request for Proposals

TDM Calibration & 2050 Population Forecast



Q: Is the MPO able to provide a list of which suggested updates from the 2020 technical memos have already been implemented to the TDM?

A: I have uploaded an PDF Table providing more details on what has and has not been completed.


Q: According to the RFP, 2020 Census data is expected by Spring of 2022. Is there an update on timing of Census data (block group level) availability?

A: That’s a great question. If the US Census Bureau has a timeline for data release at the block group level they have not shared it with us. We are as eager to get our hands on it as you are.


Q: According to the RFP, the 2021 household survey is needed before model recalibration activities can begin. When will key parameters from the survey such as trip rates, trip lengths, and auto occupancy rates be available?

A: RSG, the consultant who completed the household travel survey for us, has already provided us with their final deliverables. You can review a summary of the data by clicking below:

Travel Survey Results Summary


Q: What is the status of current regional employment data?

A: The APO purchased an employment dataset in 2020 from Infogroup (now Data Axle). APO staff has completed an initial distribution of jobs to the TAZ level, but we are currently reviewing that distribution internally to help ensure it is accurate. That internal QA/QC check will be completed by the time the consultant starts work on this project in April. However, it’s probably not a bad idea to budget at least some time to check the data for accuracy as well.


Q: On page 3 of the RFP, please clarify the APO budget available for project ($140,000 vs. $112,000).

A: I apologize for the typo and the confusion. The maximum total available funding for the project is $140,000.


Q: Will the survey consultant provide trip rates for home-based work, home-based nonwork and nonhome-based purposes from the survey?

A: The contract with the survey consultant has ended and they have provided all deliverables under their contract. Prospective respondents should budget resources to examine the survey data and calculate the specified trips rates.