Transcript TRB APP CON
Establishment of Freeway Link Volume Validation Targets based on Traffic Count Distributions in the Dallas-Fort Worth Region 15th TRB Conference on Transportation Planning Applications Atlantic City, NJ May 2015 Behruz Paschai, Arash Mirzaei, Francisco Torres North Central Texas Council of Governments (NCTCOG) 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 2015 15th TRB Conference on Transportation Planning Applications 2 Permanent Traffic Count Locations US75 115,000 < AWDT < 150,000 I820 I35E 80,000 < AWDT < 95,000 200,000 < AWDT < 250,000 I20 70,000 < AWDT < 80,000 I45 I30 70,000 < AWDT < 80,000 130,000 < AWDT < 150,000 May 2015 15th TRB Conference on Transportation Planning Applications 3 Data Cleanup Process 1. Only considered counts on Tue, Wed, and Thu 2. Eliminated counts collected on: a. 4th of July b.Thanksgiving weekend c. December 23rd - January 1st 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) May 2015 15th TRB Conference on Transportation Planning Applications 4 AAWDT AAWDT Box Plots – I35 Year Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. May 2015 15th TRB Conference on Transportation Planning Applications 5 Deviation Measures 1. Many deviation measures exist 2. APE MAPE MAE RMdSE Each measure has its own limitations: RMSPE GMRAE 1. biased towards positive differences MdAPE MdRAE SMAPE 2. cannot be used when observations include zero sMdAPE MdRAE RMdSPE 3. biased towards larger differences MASE MSE MdAE 4. difficult to explain RMSE 3. %RMSE is commonly used in the validation process although it has a more complicated definition in comparison to simpler measures such as MAPE. May 2015 15th TRB Conference on Transportation Planning Applications 6 Deviation of Counts vs AAWDT 4% %RMSE MAPE WxMAPE I30 8% 6% %RMSE MAPE WxMAPE I35E 4% 2% 2% %RMSE MAPE WxMAPE 4% I820 10% 8% %RMSE MAPE WxMAPE US75 6% 2% 4% 2% May 2015 15th TRB Conference on Transportation Planning Applications 7 Coefficient of Variance CV vs AAWDT I45 I20 I820 I30 I35E US75 Average Annual Weekday Traffic Count May 2015 15th TRB Conference on Transportation Planning Applications 8 %RMSE %RMSE vs AAWDT I20 I820 I45 I30 US75 I35E Average Annual Weekday Traffic Count May 2015 15th TRB Conference on Transportation Planning Applications 9 Average Deviation Average Deviation from AAWDT I45 I820 I20 I30 US75 I35E Average Annual Weekday Traffic Count May 2015 15th TRB Conference on Transportation Planning Applications 10 Deviation of Weekday Counts around AAWDT Deviation of Weekday Freeway Counts around AAWDT (All Locations) Average Annual Weekday Traffic Count May 2015 15th TRB Conference on Transportation Planning Applications 11 Average Percent Daily Counts Percent Weekday Freeway Counts within 5% of AAWDT (All Locations) Year May 2015 15th TRB Conference on Transportation Planning Applications 12 Average Percent Daily Counts Percent Weekday Freeway Counts within 5% of AAWDT (All Locations) Month May 2015 15th TRB Conference on Transportation Planning Applications 13 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 2015 15th TRB Conference on Transportation Planning Applications 14 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 2015 15th TRB Conference on Transportation Planning Applications 15 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. May 2015 15th TRB Conference on Transportation Planning Applications 16 Contact Information Behruz Paschai Arash Mirzaei Francisco Torres May 2015 [email protected] [email protected] [email protected] 15th TRB Conference on Transportation Planning Applications 17 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 2015 15th TRB Conference on Transportation Planning Applications 18 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 2015 15th TRB Conference on Transportation Planning Applications 19 Percent Deviation Target %RMSE Variation Around Mean Coefficient of Variation Validation Recommendation Examples Source: Model Validation and Reasonableness Checking Manual, TMIP/FHWA, February 1997. May 2015 15th TRB Conference on Transportation Planning Applications 20 Variations of AAWDT (PDFs) I30 I35E 40% 40% 20% 0% 222,500 142,500 20% 0% US75 I820 60% 40% 40% May 2015 87,500 0% 0% 15th TRB Conference on Transportation Planning Applications 132,500 20% 20% 21 Variations of AAWDT (PDFs) I20 60% 40% 20% 77,500 0% I45 60% 40% 0% May 2015 72,500 20% 15th TRB Conference on Transportation Planning Applications 22 AAWDT AAWDT Box Plots – US75 Year Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. May 2015 15th TRB Conference on Transportation Planning Applications 23 AAWDT AAWDT Box Plots – I20 Year Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. May 2015 15th TRB Conference on Transportation Planning Applications 24 AAWDT AAWDT Box Plots – I45 Year Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. May 2015 15th TRB Conference on Transportation Planning Applications 25 AAWDT AAWDT Box Plots – I30 Year Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. May 2015 15th TRB Conference on Transportation Planning Applications 26 AAWDT AAWDT Box Plots – I820 Year Note : The whiskers indicate the maximum and minimum values since the data outside of the 4*sigma range has been already removed. May 2015 15th TRB Conference on Transportation Planning Applications 27 Deviation of Counts vs AAWDT 6% %RMSE MAPE WxMAPE I20 4% 2% 8% 6% %RMSE MAPE WxMAPE I45 4% 2% May 2015 15th TRB Conference on Transportation Planning Applications 28