Enhancing TDF Model Results Using Intersection Control Specific Delays and Turning Movement Level Matrix Estimation for a Downtown Circulation Study Presented

Enhancing TDF Model Results Using Intersection Control Specific Delays and

Turning Movement Level Matrix Estimation for a Downtown Circulation Study

Presented to the 11th Conference on Transportation Planning Applications

May 9, 2007

By

Gregory Giaimo, Ohio Department of Transportation

Motivation of Presentation

• Demonstrate Use of New Techniques to Improve TDF Model Results for Project Analysis

• Emphasis on a Careful and Methodical Implementation versus “Push Button”

Two Key Tools

• Explicit Intersection Delay Modeling

• Turn Movement Level Matrix Estimation

Background on the Mansfield Traffic and Parking Study

• Various one way street configurations downtown to be analyzed

• Need opening (2012) and design year volumes for the AM and PM peak hours

• Consultant has already set up and run a Synchro analysis using the base year counted volumes and the existing operational configuration

• Task: to create good forecast turn movement volumes on these alternatives for further Synchro operational analysis to produce a final alternative

Compress car/truck, get trip end file and confidence levels

Check network & count coding

Turn counts and Synchro files from

MPO

Rerun base year model using

revised network

Extract sub area network and trip table for AM and

PM periods

Add detailed signal timing and

progression

Calculate Fratar targets at sub area

cordon

Run matrix estimation to create

final base year demand volumes

Forecast zonal variables from MPO

Check variables, reformat and fix as

necessary

Create scenarios in full model for forecast

years

Extract sub areas for each period for each

forecast year

Calculate Fratar factors by zone to adjust base year demand to future

Fratar base demand to future

Code alternative networks

Assign both periods for all three years (base, opening,

design) to all networks

Take DBF turn volumes to XLS and convert to Synchro CSV

format

Study Flow Chart

Reassign, correct obvious path

problems, reassign

Network Lane Checking• Turn lane

configurations in the model were checked vs. Synchro. These were double checked vs. aerial photos and video log.

• Errors in network were corrected and full validation model rerun.

• Some errors in the Synchro data were found and were sent to the MPO

Check Count Consistency• Turn counts were checked for

consistency in a spreadsheet

• They were also aggregated to link level and plotted on the network

• Overall, the turn counts from adjacent intersections were reasonably consistent

PM Peak Turn Volumes Aggregated to Links




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Updating Signal OperationsOver-ride signal locations

Signal phasing editor

• Updated signal timings and progression based on Synchro files

• Moral: assumed default signal operation parameters don’t work with operational level studies




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Rerun Base Year Model

Save Paths




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Extract Sub Area Net and Trip Table

• Not always necessary but helpful in this case




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Fratar Cordon Volumes• 24 Hour Link car/truck counts at cordon

converted to period level directional values using full model assignment

• Original sub area trip table Fratared




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Check for Routing Problems

• Fratared trip tables assigned and assignments checked for path problems

• Some small speed adjustments corrected most problems

• Due to odd routing of SR 13 through CBD, SR 13 through trips were placed in their own volume group to force them on the SR 13 signed route (because a much shorter path down Main Street exists but counts indicate the through traffic largely remains on the signed route)




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Prepare Inputs for Matrix Estimation

• Car/Truck are compressed, turning movement counts were by class but truck volume was too low to bother with independently

• Extract trip ends• Add confidence levels to data:

– Trip table cell 1– Internal trip end 10– External trip end 50– Older turn count 50– New turn count 75

Run Matrix Estimation

• Can accept various data items such as:– Link or turn counts– Trip ends– Seed trip table– Etc.

• All inputs require confidence levels– Relative values– Order of magnitude difference needed to see much impact

• Adjusts the trip matrix to fit the various weighted (through confidence levels) observed data with minimum error

Run Matrix Estimation (cont.)

2 Matrices required, trips and confidence level

ASCII, zone, origins, destinations, O confidence, D confidence

ASCII, screen number, from-through-to nodes, count, confidence level

The information contained in the print file is extremely important and should be well understood by anyone wishing to use matrix estimation properly

Need a path file from a previous assignment

Run Matrix Estimation Print File

Here’s information on average confidence levels and amounts of data, very important for helping set confidence levels.

This shows input matrix characteristics, the warning messages show counts that had no trips assigned in the prior assignment. This is important, a link or turn with no assignment before won’t get any in matrix estimation either.

This shows that convergence occurred and the number of iterations.

This shows how good each zones trip ends match.

This shows how well each count was matched, notice that the counts match better than trip ends due to higher confidence.




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Check Forecast Variables• Variables

checked in spreadsheet and through plots

• Noticed large discrepancy between 2000 and 2005 due to changes in assumptions

Check Forecast Variables (cont.)• In contrast the

2005 and 2030 variables are consistent and show growth in reasonable areas

• Since the forecast variables aren’t “official” it was decided to use these to derive growth factors for the base year




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Run Forecast Year Model

Base Year Model with Forecast Variables

New Scenarios added for forecast land use




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Fratar to Forecast Year

• Trip ends extracted from forecast year trip tables• Fratar factors (not targets) calculated in spreadsheet• Separate Origin and Destination factors (excerpt below is

from the Origin factor computation)




MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Code Alternative Networks

• Four alternatives– Alt. 1: Two way operation on Main and Diamond– Alt. 2: Two way operation on Main and Walnut– Alt. 3: Two way operation on Diamond, Main,

Mulberry and Walnut– Alt. 4: As Alt. 3 plus two way operation on First and

Second

• In addition to adding two way operation, lane configurations and signal operations updated appropriately

Code Alternative Networks (cont.)Nobuild (Existing) Alternative 1

TURNLANE annotated, LANES colored

Code Alternative Networks (cont.)Alternative 2 Alternative 3


Code Alternative Networks (cont.)Alternative 4





MPO


revised network


PM periods


progression


cordon





necessary


years


forecast year







format

Study Flow Chart


problems, reassign

Assign & Export to Synchro•Save Turn Volumes to DBF

•Lookup tables of Synchro direction codes and intersection ID’s required in spreadsheet to convert Cube From-Thru-To node

•A pivot table in spreadsheet then easily converts turn movements to the tabular format required by Synchro

Impact of Adjustments on VolumeOriginal Travel Demand Model Fratared Subarea Model

Impact of Adjustments on Volume (cont.)Final Model After ME Turning Movement Counts

Turn Volumes From Several Methods• The obvious question: After all this effort what is the impact on the final results?

• Different turning movement volumes are obtained using the adjusted sub-area model vs. simply coding the network changes/variables into the original model as shown below

• What impact do these differences have?

Validated Regional Model Adjusted Sub-area Model

2000 Alternative 1, PM Peak Assignment, Intersection of Diamond & Park Ave West

263 Left

389 Through

378 Right

236 Left

859 Through

353 Right

Turn Volumes From Several Methods (cont.)

• As expected the adjusted model matches counts better

• While the standard link based %RMSE of this model is 33%, the CBD turning movements have a substantially higher value of 73% for the validation year model


• The regional model using junction based assignment performs marginally better than the regional model using equilibrium when compared to counts


• However, more importantly, the sensitivity of traffic to the coded alternative is much closer to that obtained with the adjusted model


• Changes resulting from the forecast year are much smaller than the model error (without adjustments) due to the low growth in the area


• Changes resulting from the alternative are similar magnitude to the model error without adjustment

• Thus, the adjustment process and junction modeling is most likely needed to reasonably predict turning movement level outputs in an area highly regulated by traffic control devices such as the CBD

Comparison of Model LOS

Original Model Final Sub Area Model

How do these volume differences impact the decision making process?

Different Volumes, Same Methods (Year 2000 No Build Shown)

Questions

Please Use Microphone

Documents

Enhancing TDF Model Results Using Intersection Control Specific Delays and Turning Movement Level Matrix Estimation for a Downtown Circulation Study Presented