From: Kumar Neppalli <kneppalli@townofchapelhill.org>
Subject: FW: Additional recommendations for Town-wide traffic model
Date: April 23, 2021 at 5:35:30 PM EDT

To: julie McClintock <mcclintockjulie@gmail.com>
Cc: Maurice Jones <mjones@townofchapelhill.org>, Colleen Willger <cwillger@townofchapelhill.org>, Judy Johnson <jjohnson@townofchapelhill.org>, Fred Lampe <fredrl@icloud.com>

  • Calibration generally requires acquisition of additional detailed field recorded information, which may or may not be possible during COVID.  We are going to extract traffic volume data from the model results to see how well it matches the count data we are putting in it and make adjustments, as needed to replicate turning movement data – so that is the first thing you do/check when you calibrate/validate a model.  No other really “detailed” calibration is occurring at this stage.

  • The only developments that are loaded into the current Town-wide model are the ones being requested and only to be used specific for this Aura scenario test. Please see the developments provided below. The model results will be ready by May 3.

  • The “final” Town-wide model will not have any developments specifically coded into it – it’s purpose is to be a “base” to do these kind of refined studies (TIA, corridor study, signal timing optimization, planning level scenario test) where you can add developments as needed.

  • We can provide whatever model output you want, just need to define what it is.

  • All Blue Hill District TIA Development/Redevelopments – except for the University Inn Redevelopment – Information from Blue Hill District TIA

  • University Place (University Mall Redevelopment) – Information from University Place TIA (2024 Phase 1 Changes Only)

  • Aura – Information from Aura TIA

  • Estes Drive Future Developments (Central West Plan Area) – Rummel Property, YMCA Expansion, Others (Information to be provided by Town)

  • E. Rosemary Parking Deck & Office Building – Information from E. Rosemary Parking Deck & Office Building TIA

  • Union Chapel Hill Apartments – Information from Residences at Grove Park TIA

  • Town of Chapel Hill Municipal Services Center – Information from TIA

  • W. Rosemary Street Hotel – Information from TIA

_____________________________________

From: Juliemcclintock <mcclintock.julie@gmail.com> Sent: Wednesday, April 14, 2021 9:22 AM
To: Kumar Neppalli <kneppalli@townofchapelhill.org>Cc: Maurice Jones <mjones@townofchapelhill.org>; Judy Johnson <jjohnson@townofchapelhill.org>; fred lampe <fredrl@icloud.com>

Subject: Additional recommendations for Town-wide traffic model External email:

April 13, 2021

Dear Kumar, The town-wide traffic model provides an exciting tool for projecting future traffic conditions in Chapel Hill. It was reassuring to read Manager Jones’s April 9th memo to the Council saying that he was directing staff to add important data to the town-wide model. Quoting from that memo, “There have been several requests to add additional data points to our town-wide traffic model program for the Aura project. I have asked our staff to include several of the Blue Hill projects that have recently been constructed, are under construction and are currently in our entitlement process such as the University Place project.  We will also be including potential future projects like the YMCA expansion and the Rummel property.  It will take a few weeks to work through the results.” This step makes great progress toward a model that can accurately reflect future traffic conditions. We are making a couple of follow up requests that are important to us and critical to the validity of model traffic forecasts. First, the model must be calibrated. A Transportation and Connectivity Advisory Board member raised the need for model calibration at the April 5th meeting. The current lack of calibration was one of the reasons the TCAB did not believe the Aura project simulation. Only when the model is properly calibrated can future projections be expected to be reasonably valid. It’s very important that the model is calibrated properly by using past traffic data and projecting from this to a known recent time period with known data. The projections are then compared to the known conditions and the model is considered calibrated if the known data and projected data compare favorably.  Projected conditions must also be able to simulate actual empirical observation of vehicle traffic bottlenecks. If the projected and known conditions do not agree, adjustments will need to be made to calibrate the model so that reality and projections agree. Second, to project future conditions and simulate future road conditions accurately, the model needs to be filled with all the relevant data associated with future conditions, including pedestrian, bike and transit trips. We request a comprehensive list of the intersections and developments that are currently loaded in the Transmodeler database. Providing the public a list of the developments already loaded into the model should be a protocol for model runs. Making this input data available routinely will restore confidence in the accuracy of the model for predicting future conditions.  We note here that during the Aura 2024 traffic simulation demonstration shown on March 30, it was mentioned that approximately 100 signal controlled intersections around Town were loaded in the model, but few if any stop sign intersections were included in the model. Likewise, only 3 specific proposed developments were included, i.e. University Place, 1200 MLK and Aura itself. Since there are a large number of developments actually under construction all over town at this time, we need to know that all of these are included in the model data set — along with immediate area stop sign controlled intersections.  Once confidence is established in the model, a Town policy can be established that provides guidelines for requesting “model runs” by staff, residents and developers. In addition, the staff needs to ensure the 2001 Guidelines for Traffic Impact Analysis that the Town has planned to update for several years —  to include using current state-of-the-art modeling tools — finally happens.  To summarize then, we request that the Town:

  • Calibrate the model

  • Provide a comprehensive list of the intersections and developments that are currently loaded in the Transmodeler data base and which new development data will be loaded.

  • Present the model output to the public after completing Manager Jone’s request as noted above.

 Please keep the public informed about the timetable for this very important work.  Thank you!

Sincerely,  Fred Lampe and Julie McClintock
Estes Neighbors