Establishment of Freeway Link Volume Validation Targets based on Traffic Count Distributions in the Dallas-Fort Worth Region Behruz Paschai, Arash Mirzaei, Francisco Torres North Central Texas Council of Governments (NCTCOG) 15 th TRB Conference on Transportation Planning Applications Atlantic City, NJ May 2015

15 th TRB Conference on Transportation Planning Applications2 Objectives Using the historical freeway counts in the region and comparing the actual counts versus the actual AAWDTs: -Evaluate the traffic count variations and compare with the available data from other regions -Evaluate and recommend appropriate validation measures -Evaluate the statistical significance built in to the link volume validation process -Evaluate the errors associated with estimating the AAWDTs.

May th TRB Conference on Transportation Planning Applications3 Permanent Traffic Count Locations 115,000 < AWDT < 150, ,000 < AWDT < 250,000 80,000 < AWDT < 95, ,000 < AWDT < 150,000 I35E I30 I820 US75 70,000 < AWDT < 80,000 I45 70,000 < AWDT < 80,000 I20

May th TRB Conference on Transportation Planning Applications4 Data Cleanup Process 1.Only considered counts on Tue, Wed, and Thu 2.Eliminated counts collected on: a.4 th of July b.Thanksgiving weekend c.December 23 rd - January 1 st 3.Eliminated counts that were outside 4*Sigma around the AAWDT (not more than 5 winter days in January and February when we probably had a winter storm event)

5 AAWDT Box Plots – I35 May th TRB Conference on Transportation Planning Applications Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. AAWDT Year

6 Deviation Measures May th TRB Conference on Transportation Planning Applications 1.Many deviation measures exist 2.Each measure has its own limitations: 1.biased towards positive differences 2.cannot be used when observations include zero 3.biased towards larger differences 4.difficult to explain 3.%RMSE is commonly used in the validation process although it has a more complicated definition in comparison to simpler measures such as MAPE. RMSE APE MAPE MAE RMdSE RMSPE GMRAE MdAPE MdRAE SMAPE sMdAPE MdRAE MASE RMdSPE MSE MdAE

7 Deviation of Counts vs AAWDT May th TRB Conference on Transportation Planning Applications I35E I30 I820 US75 2% 4% 2% 4% 2% 4% 6% 8% 2% 4% 6% 8% 10% %RMSE MAPE WxMAPE %RMSE MAPE WxMAPE %RMSE MAPE WxMAPE %RMSE MAPE WxMAPE

8 CV vs AAWDT May th TRB Conference on Transportation Planning Applications I35E I30 I820US75 Average Annual Weekday Traffic Count Coefficient of Variance I20 I45

9 %RMSE vs AAWDT May th TRB Conference on Transportation Planning Applications I35E I30 I820 US75 Average Annual Weekday Traffic Count %RMSE I45 I20

10 Average Deviation from AAWDT May th TRB Conference on Transportation Planning Applications Average Annual Weekday Traffic Count Average Deviation I35E I30 I820 US75 I20 I45

11 Deviation of Weekday Freeway Counts around AAWDT (All Locations) May th TRB Conference on Transportation Planning Applications Average Annual Weekday Traffic Count Deviation of Weekday Counts around AAWDT +10% -10% +5% -5% -20% +20%

12 Percent Weekday Freeway Counts within 5% of AAWDT (All Locations) May th TRB Conference on Transportation Planning Applications Year Average Percent Daily Counts

13 Percent Weekday Freeway Counts within 5% of AAWDT (All Locations) May th TRB Conference on Transportation Planning Applications Month Average Percent Daily Counts

May th TRB Conference on Transportation Planning Applications14 Preliminary Conclusions 1.Similarities can be observed in the daily variation of traffic volumes on freeways across the country. 2.On average 80%-90% of the weekday counts at the studied locations are within 5% of their corresponding AAWDT. 3.The probability of getting a count on the freeways that is within 5% of AAWDT is highest when collected between March and October (excluding the major holidays).

May th TRB Conference on Transportation Planning Applications15 Preliminary Conclusions 4.Prefer to use MAPE over %RMSE as a measure of deviation. 5.For all practical purposes, Tue, Wed, and Thu are similar in total daily traffic and its variation. 6.The provided graphs compare the actual daily counts against the actual AAWDTs. Validation targets need to be set with accounting for errors in calculating the AAWDTs.

May th TRB Conference on Transportation Planning Applications16 Next Steps 1.Evaluate the traffic conditions in the peak hours. 2.Evaluate the accuracy of the AAWDT estimations based on daily counts and calculated factors from previous years.

17 Contact Information Behruz Paschai Arash Mirzaei Francisco Torres May th TRB Conference on Transportation Planning Applications

May th TRB Conference on Transportation Planning Applications18 Background Daily Roadway Traffic Counts are Random Variables - TMIP Validation Manual provides examples of validation requirements/recommendations from Florida, Ohio, and Oregon. - Validation measures are typically: -%RMSE, MAPE, or CV -A function of AADT - Acceptable ranges could be presented as a confidence intervals around the AADT.

May th TRB Conference on Transportation Planning Applications19 Available Historical Data 1.Traffic counts obtained from permanent count stations 2.Utilized the data from six freeway locations that: a.had 7-10 years of daily historical data between years 2004 and 2014 b.represented different weekday count ranges or similar ranges on different facility types (AAWDT 70k-250k) c.represented urban and rural areas

May th TRB Conference on Transportation Planning Applications20 Validation Recommendation Examples Source: Model Validation and Reasonableness Checking Manual, TMIP/FHWA, February Coefficient of Variation Variation Around Mean Percent Deviation Target %RMSE

21 Variations of AAWDT (PDFs) May th TRB Conference on Transportation Planning Applications I35E I30 I820 US75 40% 20% 40% 20% 40% 20% 40% 20% 142,500 87, ,500 60% 222,500 0%

22 Variations of AAWDT (PDFs) May th TRB Conference on Transportation Planning Applications I45 I20 40% 20% 40% 20% 77,500 72,500 60% 0%

23 AAWDT Box Plots – US75 May th TRB Conference on Transportation Planning Applications Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. AAWDT Year

24 AAWDT Box Plots – I20 May th TRB Conference on Transportation Planning Applications Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. AAWDT Year

25 AAWDT Box Plots – I45 May th TRB Conference on Transportation Planning Applications Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. AAWDT Year

26 AAWDT Box Plots – I30 May th TRB Conference on Transportation Planning Applications Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. AAWDT Year

27 AAWDT Box Plots – I820 May th TRB Conference on Transportation Planning Applications Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. AAWDT Year

28 Deviation of Counts vs AAWDT May th TRB Conference on Transportation Planning Applications I45 I20 2% 4% 6% 8% 2% 4% 6% %RMSE MAPE WxMAPE %RMSE MAPE WxMAPE