ODOT Traffic Academy Interchange Studies (IJS/IMS/IOS) September 2017
Curse Outline Sectin 1... Plicies and Overview Purpse... 6-7 FHWA Authrity... 8 FHWA Plicies... 9-10 ODOT Plicies... 11 Plicy Pint 1... 12-13 Plicy Pint 2... 14-15 Best Practices (2009 Plicy Pints)... 16-22 Types f Interchange Studies... 23 When an IJS/IMS/IOS is Required... 24-26 When an IJS/IMS/IOS is nt Required... 27 Crdinatin with ODOT PDP... 28 Review Prcess... 29-30 Apprval Authrity... 31 Sectin 2... Reprt Cntent Reprt Outline... 33 Executive Summary... 34 Backgrund... 35 Purpse and Need... 36 Study Area... 37 Existing Cnditins... 38 Analysis Years... 39 Alternatives Cnsidered... 40-42 Traffic Vlumes... 43 Traffic Analyses... 44-48 Cst Estimate... 49 Traffic Academy Interchange Studies
Cnclusin and Recmmendatins... 50 Sectin 3... Analyses Analyses... 52 IJS/IMS Analysis Pints... 53 ODOT HCS Standards (Freeways/Ramps)... 54-56 ODOT HCS Standards (Majr Merge)... 57-59 ODOT HCS Standards (Majr Diverge)... 60-63 ODOT HCS Standards (Mainline Weave)... 64-75 ODOT HCS Standards (Signals)... 76-78 Balancing Delays... 79-96 LOS Requirements... 97-100 Cnstrained Traffic... 101-117 Types f Mitigatin... 118-119 Turn Lane Strage... 120-131 IOS Reprt Cntent... 132-136 IMS Addendum... 137-141 Cmmn Review Cmments... 142-146 Traffic Academy Interchange Studies
TRAFFIC ACADEMY INTERCHANGE STUDIES ODOT CENTRAL OFFICE, SEPTEMBER 21 ST 2017
2 Traffic Academy - Interchange Studies
TESTING 3 Traffic Academy - Interchange Studies
5 SECTIONS OF THE COURSE Plicies and Overview IJS/IMS Reprt Cntent IJS/IMS Analyses IOS Reprt Cntent Addendum 4 Traffic Academy - Interchange Studies
POLICIES & OVERVIEW 5 Traffic Academy - Interchange Studies
PURPOSE T dcument the impacts f prpsed wrk in the interchange area fr: New Interchange Lcatins Mdificatins t Existing Interchange Lcatins 6 Traffic Academy - Interchange Studies
PURPOSE T dcument evidence that the Level f Service (LOS) f the freeway peratins des nt degrade when cmparing the N Build cnditin t the Build cnditin Blueprint fr the Build Cnditin 7 Traffic Academy - Interchange Studies
FHWA AUTHORITY Title 23, United States Cde, Highways Sectin 111 (23 U.S.C. 111), Agreements relating t use f and access t ROW - Interstate System Secretary f USDOT delegated the authrity t administer 23 U.S.C. 111 t the FWHA by 49 CFR 1.48 (b)(1) 8 Traffic Academy - Interchange Studies
FHWA POLICIES FHWA Plicy Statement, Access t the Interstate System May 22, 2017 First issued in Octber 1990 Updated n February 4, 1998 Updated n August 27, 2009 http://www.fhwa.dt.gv/prgramadmin /fraccess.cfm 9 Traffic Academy - Interchange Studies
FHWA POLICIES Interstate System Access An Infrmatinal Guide, August 2010 http://www.fhwa.dt.gv/design/in terstate/pubs/access/access.pdf AASHTO, A Plicy n Design Standards Interstate System, January 2005 10 Traffic Academy - Interchange Studies
ODOT POLICIES Lcatin & Design (L&D) Manual, Vlume I, Sectin 550 Requests fr New r Revised Access Sectin 550.2 currently mirrrs the 2009 FHWA plicy. It will be updated t match the 2017 plicy. ODOT uses a similar methdlgy as FHWA t evaluate an IMS n a nninterstate freeway 11 Traffic Academy - Interchange Studies
POLICY POINT 1 Evidence is prvided thru analyses that the prpsed build cnditin des nt degrade peratins cnsidering: 20 Year Design N Build LOS vs. Build LOS (N Degradatin!) Established LOS criteria Cnceptual Signing Plan fr Cmplex Prjects identifying type and lcatin f signs 12 Traffic Academy - Interchange Studies
STUDY AREA FOR IJS/IMS *Next Significant Intersectin within ½ mile Interchange being studied Study Area *Additinal intersectins may be required if they are clsely spaced r part f a crdinated system. 13 Traffic Academy - Interchange Studies
POLICY POINT 2 All traffic mvements are prvided Partial interchanges cnsidered n case-bycase basis Must include analysis f a full interchange ptin Must include mitigatin fr missing mvements Cnnectin is t a public rad Design meets r exceeds current standards 14 Traffic Academy - Interchange Studies
POLICY POINT 2 Example f a split diamnd interchange Example f a partial interchange 15 Traffic Academy - Interchange Studies
BEST PRACTICES (2009 POLICY POINTS) Existing infrastructure cannt be imprved t satisfy design year demand traffic Need is based upn reginal traffic demands, nt lcal Justificatin cannt include enhanced prperty values r access t private facilities 16 Traffic Academy - Interchange Studies
BEST PRACTICES (2009 POLICY POINTS) All reasnable alternatives fr design ptins, lcatin and Transprtatin System Management (ramp metering, transit, HOV, etc.) have been cnsidered and cannt satisfy the demand 17 Traffic Academy - Interchange Studies
BEST PRACTICES (2009 POLICY POINTS) Fr new interchanges: Spacing (L&D Manual, Sectin 502.3) Urban area, 2 miles, I mile minimum Suburban area, 4 miles, I mile minimum Rural area, 8 miles, 3 miles minimum 18 Traffic Academy - Interchange Studies
BEST PRACTICES (2009 POLICY POINTS) In crridrs where the ptential exists fr future multiple interchange imprvements, ensure IMS analysis cnsiders all funded imprvements in the crridr. 19 Traffic Academy - Interchange Studies
BEST PRACTICES (2009 POLICY POINTS) Revised access generated by new r expanded develpment shall prvide evidence f crdinatin between the develpment and transprtatin imprvements 20 Traffic Academy - Interchange Studies
BEST PRACTICES (2009 POLICY POINTS) Prpsed alternative has been evaluated in the envirnmental prcess The IMS is nt Step 1 f the PDP 21 Traffic Academy - Interchange Studies
BEST PRACTICES (2009 POLICY POINTS) IJS/IMS reprts are cnditinally apprved by FHWA District must then request final apprval f the IMS frm FHWA nce NEPA is finalized 22 Traffic Academy - Interchange Studies
TYPES OF INTERCHANGE STUDIES Types f Interchange Studies IJS Interchange Justificatin Study IMS Interchange Mdificatin Study IOS Interchange Operatins Study 23 Traffic Academy - Interchange Studies
WHEN AN IJS IS REQUIRED New interchange at a new lcatin 24 Traffic Academy - Interchange Studies
WHEN AN IMS IS REQUIRED Recnfigured interchange at an existing lcatin Changing interchange type Adding a ramp Relcating ramp terminal t different rad Significant peratinal changes (adding C-D rads) 25 Traffic Academy - Interchange Studies
WHEN AN IOS IS REQUIRED Altering the number and/r type f lanes at crssrad ramp intersectin Rad diets Turn lane additins Thru lane additins Changing lane type withut adding r reducing lanes Revising single lane ramps t dual lanes (exit and/r entrance ramps) Adding an auxiliary lane between tw adjacent interchange ramps (preferably less than 1 mile) where the single auxiliary lane des nt functin as a mainline travel lane 26 Traffic Academy - Interchange Studies
WHEN AN INTERCHANGE STUDY IS NOT REQUIRED Installing signals at ramp intersectins Extending turn lane lengths n exit ramp r crssrad Mainline thru lane additins Imprving radway features t meet current gemetric standards (i.e. cnstructing accel/decel lanes r radii t current standards) Adding ramp metering NOTE: Any imprvement needs t meet design standards and peratinal requirements 27 Traffic Academy - Interchange Studies
COORDINATION WITH ODOT PDP The IMS will be cmpleted after determinatin f the Preferred Alternative. Depending upn the scpe f the prject, the IMS ccurs after the Feasibility Study r the Alternatives Evaluatin Reprt and befre detailed design 28 Traffic Academy - Interchange Studies
REVIEW PROCESS L&D Manual, Vl. I, Sectin 550.5 Submissins are sent t the District The District will submit t ORE 29 Traffic Academy - Interchange Studies
REVIEW PROCESS ORE will frward interstate IJS/IMS prjects t FHWA fr apprval ODOT requires an electrnic cpy f the final apprved dcument Reevaluatin f IMS may be required if cnstructin f any phase has nt started within 3 years f IMS apprval 30 Traffic Academy - Interchange Studies
APPROVAL AUTHORITY L&D Manual, Vl. I, Sectin 550.5 ORE has apprval authrity n nninterstate freeways and Interstate IOS reprts FHWA Ohi has apprval authrity n Interstate IMS/IJS reprts FHWA Ohi will crdinate with FHWA (Washingtn D.C.) as necessary 31 Traffic Academy - Interchange Studies
IJS/IMS REPORT CONTENT 32 Traffic Academy - Interchange Studies
REPORT FORMAT/OUTLINE Executive Summary Backgrund Purpse and Need Study Area Existing Cnditins Analysis Years Alternatives Cnsidered Traffic Vlumes Traffic Analyses Cst Estimate Cnclusin and Recmmendatins Appendices and Exhibits 33 Traffic Academy - Interchange Studies
EXECUTIVE SUMMARY Summarize key pints f study Purpse Analyses Cnclusin and Recmmendatins 34 Traffic Academy - Interchange Studies
BACKGROUND Describe Prject New r revised access pint Interchange lcatin MPO invlvement, as applicable Include Cunty-Rute-Sectin and PID (e.g. CUY-271-10.87, PID 97676) 35 Traffic Academy - Interchange Studies
PURPOSE AND NEED Already dne as part f envirnmental prcess thrugh prject develpment Include brief summary 36 Traffic Academy - Interchange Studies
STUDY AREA Describe interchange lcatin, including: Summarize in bullet pints and graphics rather than lng passages f text Reginal and/r lcal transprtatin functin Adjacent interchanges Crridr descriptin Include maps General Lcatin Map Study Area Map 37 Traffic Academy - Interchange Studies
EXISTING CONDITIONS EXISTING CONDITIONS Rad Gemetry & Access Lcatins Functinal classificatins Psted & Design speed limits (existing and prpsed) Existing interchange cnfiguratin Existing lane cnfiguratins Deficient gemetric cmpnents Traffic cntrl/signal spacing Summarize in bullet pints and/r schematics Physical Cnditins Terrain Safety Issues Crash data if relevant and identified causes frm previus studies - reference study in reprt 38 Traffic Academy - Interchange Studies
ANALYSIS YEARS Identify the Opening Year (typically based upn funds availability) Identify the Design Year (20 years frm Opening Year) 39 Traffic Academy - Interchange Studies
ALTERNATIVES CONSIDERED Briefly Discuss: N Build alternative Alternatives cnsidered and dismissed Transprtatin System Management (TSM) cnsideratins Lcal rad imprvements Build alternative 40 Traffic Academy - Interchange Studies
ALTERNATIVES CONSIDERED ALTERNATIVES CONSIDERED Build Alternative Include statement f cmpliance with requirements including mitigative measures Discuss any knwn design exceptins r gemetric issues Include Schematic f Build Cnditin Number and type f lanes Turn lane lengths Limited Access Right-f-Way (L/A ROW) 41 Traffic Academy - Interchange Studies
ALTERNATIVES CONSIDERED ALTERNATIVES CONSIDERED L/A ROW Limits Shw L/A ROW Limits n schematics Interchange access cntrl established in L&D Manual, Sectin 801.2.5 600 minimum frm ramp intersectin fr stp cnditin 1000 minimum frm ramp intersectin fr free flw cnditin Intent is t minimize influence f adjacent drives n interchange peratins 42 Traffic Academy - Interchange Studies
TRAFFIC VOLUMES TRAFFIC VOLUMES IMS/IJS Must be certified by ODOT s Mdeling and Frecasting Sectin Include certified traffic plates in the appendices 43 Traffic Academy - Interchange Studies
TRAFFIC ANALYSES Dcument the impact f the interchange imprvements n the interstate/freeway system based n design year traffic Include graphics fr LOS and Turn Lane Lengths 44 Traffic Academy - Interchange Studies
TRAFFIC ANALYSES Summarize HCS results f N Build & Build peratins fr the preferred alternative: Freeway sectin HCS analyses Ramp merge and diverge HCS analyses Weave HCS analyses Ramp intersectin HCS analyses including cnstrained analyses, as applicable Adjacent intersectin HCS analyses 45 Traffic Academy - Interchange Studies
TRAFFIC ANALYSES Prvide tables & exhibits t dcument impacts Include LOS table(s) and exhibits fr intersectin & freeway analysis pints Include table(s) f prpsed turn lane lengths fr the Build Cnditin..(if it is nt feasible t meet required lengths, dcument why) 46 Traffic Academy - Interchange Studies
TRAFFIC ANALYSES Level f Service Exhibits AM/PM: N-Build AM/PM: Build 47 Traffic Academy - Interchange Studies
TRAFFIC ANALYSES Detailed infrmatin shuld be included in the appendix All sftware printut analyses Submit sftware files (HCS, Synchr/SimTraffic, etc.) Turn lane length calculatins (including thru blckage) 48 Traffic Academy - Interchange Studies
COST ESTIMATE Estimate csts fr all identified imprvements including ROW impacts Identify funding surces and status in the MPO s TIP r ther plans 49 Traffic Academy - Interchange Studies
CONCLUSION & RECOMMENDATIONS Easily understd summatin f infrmatin cntained in previus text State why the recmmended imprvements (Build Cnditin) best serve the identified need Identify required mitigative measures, as applicable 50 Traffic Academy - Interchange Studies
IJS/IMS ANALYSES 51 Traffic Academy - Interchange Studies
ANALYSES Analysis Pints ODOT HCS Standards Balancing Delays LOS Requirements Cnstrained Traffic Turn Lane Strage 52 Traffic Academy - Interchange Studies
IJS/IMS ANALYSIS POINTS Only analyze the near side f adjacent interchange if it is a system interchange *Next Significant intersectin within ½ mile * * Interchange being studied * * * Merge Analysis Diverge Analysis Mainline Analysis Weave Analysis (if applicable) *Additinal intersectins may be required if they are clsely spaced r part f a crdinated system. 53 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (FREEWAYS/RAMPS) HCS Parameters: Peak Hur Factr (PHF) Use HCM default f 0.94 Free Flw Speed (FFS) Freeway sectin use design speed Ramp merge/diverge use: 15 MPH less than mainline (straight ramps) Cnsider less fr lp ramps (design speed f curve) 54 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (FREEWAYS/RAMPS) Freeway Segment Freeway Segment Freeway Segment Multiple vlumes by 2 Analyze as 2-lane segment Similar analyses apply t cnverging radways Freeway Segment Multiple vlumes by 2 Analyze as 2-lane segment 55 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (FREEWAYS/RAMPS) Freeway Segment Diverge (1-lane) Freeway Segment Freeway Segment Merge (1-lane) Freeway Segment 56 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (MAJOR MERGE) Majr Merge (Gemetry) Tw radways, each having multiple lanes, merge t frm a single freeway segment HCM 2010, Exhibit 13-18, Page 13-26 57 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (MAJOR MERGE) Majr Merge (Gemetry) Tw gemetric categries (a) # f entering lanes = # f exiting lanes 1 (b) # f entering lanes = # f exiting lanes HCM 2010, Exhibit 13-18, Page 13-26 58 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (MAJOR MERGE) Majr Merge (Analysis) N effective mdels f perfrmance Analyze by checking capacity f apprach lanes and dwnstream segment Freeway Segment Freeway Segment HCM 2010, Exhibit 13-18, Page 13-26 59 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (MAJOR DIVERGE) Majr Diverge (Analysis) A multilane radway splitting int tw multilane segments HCM 2010, Exhibit 13-19, Page 13-27 60 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (MAJOR DIVERGE) Majr Diverge (Analysis) Tw gemetric categries (a) # f entering lanes = # f exiting lanes (b) # f entering lanes = # f exiting lanes + 1 HCM 2010, Exhibit 13-19, Page 13-27 61 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (MAJOR DIVERGE) Majr Diverge (Analysis) Analyze by checking capacity f apprach lanes and dwnstream segments Failure ccurs when demand flw rate exceeds capacity f the segment Freeway Segment Freeway Segment HCM 2010, Exhibit 13-19, Page 13-27 62 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (MAJOR DIVERGE) Majr Diverge (Analysis) HCM Equatin 13-26 cmputes the average density acrss all appraching freeway lanes within 1,500 feet f the diverge =. D nt use frmula if any f the entering/exiting segment(s) are vercapacity (LOS F). D MD = Majr diverge density in influence area (pc/mi/ln) v F = Demand flw rate immediately upstream f majr diverge influence area (pc/h) N = Number f lanes appraching the majr diverge 63 Traffic Academy - Interchange Studies
HCS 2010 WEAVE HCM 2010, Exhibit 12-3, Page 12-4 64 Traffic Academy - Interchange Studies
HCS 2010 WEAVE HCM 2010, Exhibit 12-4, Page 12-5 65 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 1 What is the Level f Service f this existing ne sided weave? Certified traffic data: V FF = 2,290 vph V RF = 560 vph V FR = 310 vph V RR = 180 vph 66 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 1 Cnfiguratin characteristics: ID = 0.5 (3 miles upstream and dwnstream) LC RF = 1 (min. lane changes ramp t freeway) LC FR = 1 (min. lane changes freeway t ramp) N WL = 2 (zer r ne lane change) LC RR is nly applicable fr 2 sided weaves 67 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 1 HCS 2010 Output Weaving Segment Speed, Density, Level f Service and Capacity Weaving segment flw rate, v 3,554 veh/h Weaving segment capacity, c W 6,006 veh/h Weaving segment v/c rati 0.592 Weaving segment density, D 21.2 pc/mi/ln Level f service, LOS C Weaving intensity factr, W 0.269 Weaving segment speed, S 58.9 mi/h Average weaving speed, S W 64.7 mi/h Average nn-weaving speed, S NW 57.1 mi/h Maximum weaving length, L max 5,107 ft 68 Traffic Academy - Interchange Studies
FREEWAY WEAVING WORKSHEET 69 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 2 Des this prpsed build cnditin functin as a weave? Certified traffic data: V FF = 1590 vph V RF = 1120 vph V FR = 1100 vph V RR = 790 vph 70 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 2 Cnfiguratin characteristics: ID = 0.5 (3 miles upstream and dwnstream) LC RF = 0 (min. lane changes ramp t freeway) LC FR = 1 (min. lane changes freeway t ramp) N WL = 3 (zer r ne lane change) LC RR is nly applicable fr 2 sided weaves 71 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 2 HCS 2010 Output Weaving segment flw rate, v Weaving segment capacity, c W Weaving segment v/c rati Weaving segment density, D Level f service, LOS Weaving intensity factr, W Weaving segment speed, S Average weaving speed, S W Average nn-weaving speed, S NW Maximum weaving length, L max 6,087 ft Ntes*: a. Weaving segments lnger than the calculated maximum length shuld be treated as islated merge and diverge areas using the prcedures f Chapter 13, Freeway Merge and Diverge Segments. b. Fr vlumes that exceed the weaving segment capacity, the level f service is F. 72 Traffic Academy - Interchange Studies
FREEWAY WEAVING WORKSHEET 73 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 2 In cases where a weave is suspected, prvide the fllwing The certified weave vlumes The HCS Weave analysis which verifies that the maximum weave length is exceeded 74 Traffic Academy - Interchange Studies
WEAVE EXAMPLE 2 In cases where the actual weave length is greater than the maximum weave length, prvide the fllwing HCS Basic Freeway Segment (BFS) analysis f the mainline segment between the ramps, #1 HCS BFS analyses f the n and ff ramps, #2, 3 Micrsimulatin may be needed t accurately analyze this scenari 75 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (SIGNALS) Sectin 401.2 & Figure 401-14a f the L&D Manual Use current versin f HCS and the fllwing standard values fr signalized intersectins Peak Hur Factr (PHF) = Use HCS 7 Defaults Right Turn n Red Percentage (RTOR) = 0 Startup Lst Time = 2 secnds 76 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (SIGNALS) Requirement - Balanced Apprach Delay*: Wrst f the east/west apprach delay shall be balanced within 3 secnds f the wrst nrth/suth apprach delay *Used fr designing the intersectin based upn 20 year design traffic, NOT fr determining field signal peratins 77 Traffic Academy - Interchange Studies
ODOT HCS STANDARDS (SIGNALS) N Build Cnditin Any failing mvement (v/c > 1.0) shuld be mitigated by adding/altering lanes and/r revising signal phasing/timing as necessary Build Cnditin (t apprpriately size the intersectin) v/c ratis shall typically be less than 0.93 t be cnsidered acceptable Dente when v/c 0.93 and state why it cannt be < 0.93 Refer t L&D Manual, Sectin 401.2 78 Traffic Academy - Interchange Studies
HCS BALANCING APPROACH DELAY Examples f Signalized Intersectin Intersectin with 4 appraches Intersectin with 3 appraches 79 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 80 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 Initial Guess n Green Time fr Signal Operatins: Cycle Length = 90 s ; 2 phase Green fr L/T/R East/West = 60 s Green fr L/T/R Nrth/Suth = 20 s Cmpare apprach delays 81 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 T be balanced, the highest East/West apprach delay needs t be within 3 secnds f the highest Nrth/Suth apprach delay. Nt Balanced! 50s - 13s = 37 sec 82 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 83 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 Attempt #2 Redistribute green time: Give mre time t NB/SB Take away frm EB/WB Cycle Length = 90 sec; 2 phase Green fr all East/West L/T/R = 50s Green fr all Nrth/Suth L/T/R= 30s 84 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 Nt Balanced: Highest E/W apprach delay is almst equal t the highest N/S, but EB Left delay is significantly higher than any ther f the mvements delays Lks Balanced, but is nt! 85 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 86 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 Attempt #3 Redistribute green time: Give mre time t EB Left by adding left turn phase Cycle Length = 90 sec; 3 phase Green fr East/West Lt prtected = 7 s Green fr permitted East/West = 42 s Green fr all Nrth/Suth = 26 s Cmpare apprach delays 87 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 v/c < 1.0 Cntrl Delays Apprach Delays Apprach delays are balanced & all v/c ratis fr all individual mvements are less than 1.0 Balanced! 88 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 1 89 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 2 90 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 2 Initial Guess n Green Time fr Signal Operatins: Cycle Length = 90 sec. ; 3 phase Green fr Prt. EB Lt & Thru = 15 s Green fr East/West Permit. = 40 s Green fr NB Exit Ramp = 20 s Cmpare highest EB/WB delay with highest NB apprach delays 91 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 2 T be balanced, the highest East/West apprach delay shuld be within 3 sec. f the highest Nrth apprach delay Nt Balanced! 69.9s - 21.4s = 48.5 sec 92 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 2 93 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 2 Attempt #2 Redistribute green time, Give mre time t NB phase Cycle Length = 90 sec. ; 3 phase Green fr Prt. EB Lt & Thru = 15 s Green fr East/West Permit. = 32 s Green fr NB Exit Ramp = 28 s Cmpare highest EB/WB delay with highest NB apprach delays 94 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 2 v/c < 1.0 Cntrl Delays Apprach Delays Apprach delays are balanced and all v/c ratis fr individual mvements are less than 1.0 Balanced! 95 Traffic Academy - Interchange Studies
HCS BALANCING: EXAMPLE 2 96 Traffic Academy - Interchange Studies
LOS REQUIREMENTS LOS requirements fr interstate/freeway system and interchange cmpnents (Build Cnditin) LOS C is desired LOS D acceptable in urban areas with ODOT & MPO apprval 97 Traffic Academy - Interchange Studies
LOS REQUIREMENTS If: The Build LOS drps a letter grade (t an unacceptable LOS) frm N-Build r LOS remains an F Then: Unacceptable Degradatin may be ccurring 2% Rule is applied t determine 98 Traffic Academy - Interchange Studies
LOS REQUIREMENTS - URBAN/SUBURBAN If N-Build = D & Build = D If N-Build = E & Build = E If N-Build = D & Build = E If N-Build = E & Build = F If N-Build = F & Build = F N Degradatin (Cnstrained Analyses are nt Required) Check fr Degradatin with 2% Rule (Cnstrained Analyses Required) 99 Traffic Academy - Interchange Studies
LOS REQUIREMENTS - RURAL If N-Build = C & Build = C If N-Build = D & Build = D If N-Build = E & Build = E N Degradatin (Cnstrained Analyses are nt Required) If-N-Build = C & Build = D If N-Build = D & Build = E If N-Build = E & Build = F If N-Build = F & Build = F Check fr Degradatin with 2% Rule (Cnstrained Analyses Required) 100 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC Cnstrained Traffic ccurs when all the traffic desiring t enter the freeway (demand vlume) cannt d s, i.e., v/c ratis fr entering mvements are greater than 1.0 Nte: This nly needs t be evaluated if pssible degradatin is ccurring 101 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC It is necessary t determine the difference between the vlume getting nt the freeway in the N Build cnditin vs. the Build cnditin The 2% Rule See L&D Manual, Sectin 550.2 A prpsed change is deemed t degrade freeway peratins if it increases traffic n the dwnstream freeway merge and/r freeway segment by 2.00% r mre, OR dwnstream weave segment by 2.00% r mre 102 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC Examples: < 2% > 2% 103 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC EXAMPLE 1 LOS F Traffic vlumes are the same fr N- Build and Build 104 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 1 Prblem: Determine whether an additinal EB & NB left turn lane will degrade the freeway peratins. Balance N-Build & Build ramp intersectins Determine v/c s fr all the mvements cntributing t the ramp vlume. If v/c > 1.0, the mvement is cnstrained. The full demand vlume fr the mvement is divided by the v/c t determine the cnstrained vlume that can make it t the ramp. 105 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC EXAMPLE 1 Balanced N-Build HCS N-Build Ramp Vlume (Cnstrained) Nte: If v/c 1.0, then v/c=1.0 If v/c>1.0, then v/c=v/c = / +# / +$ / 480 1.19 + 390 1.00 + 1 1.28 = 403+390+1=794 106 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 1 Balanced Build HCS Build Ramp Vlume (Cnstrained) Nte: If v/c 1.0, then v/c=1.0 If v/c>1.0, then v/c=v/c = / +# / +$ / 480 1.03 + 390 1.00 + 1 1.00 = 466+390+1 = 857 107 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 1 Cnstrained N-Build Ramp Vlume a 794 Cnstrained Build Ramp Vlume a 857 δ = (Build N Build) = 857-794 δ = 63 additinal vehicles entering the freeway in the Build Cnditin = δ 011 23 45678 24 9:;<=>?@ A=>>B?C D375@> E F23 45678 G?@: D375@>H = δ 011 = LM 011 I111EJKI IJKI = 1.31% O < 2% N Degradatin! 108 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 1 109 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 1 110 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC EXAMPLE 2 LOS F Traffic vlumes are the same fr N- Build and Build 111 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 2 Prblem: Determine whether an additinal EB left turn lane and WB thru lane will degrade the freeway peratins. Balance N-Build & Build ramp intersectins Determine v/c s fr all the mvements cntributing t the ramp vlume. If v/c > 1.0, the mvement is cnstrained. The full demand vlume fr the mvement is divided by the v/c t determine the cnstrained vlume that can make it t the ramp. 112 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 2 Balanced N-Build HCS N-Build Ramp Vlume (Cnstrained) Nte: If v/c 1.0, then v/c=1.0 If v/c>1.0, then v/c=v/c = / +# / +$ / 550 1.23 + 500 1.00 + 5 1.16 = 447+500+4 = 951 113 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC - EXAMPLE 2 Balanced Build HCS Build Ramp Vlume (Cnstrained) Nte: If v/c 1.0, then v/c=1.0 If v/c>1.0, then v/c=v/c = / +# / +$ / 550 1.00 + 500 1.00 + 5 1.00 = 550+500+5 = 1,055 114 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC EXAMPLE 2 Cnstrained N-Build Ramp Vlume a 951 Cnstrained Build Ramp Vlume a 1055 δ = (Build N Build) = 1055-951 δ = 104 additinal vehicles entering the freeway in the Build Cnditin = δ 011 23 45678 24 9:;<=>?@ A=>>B?C D375@> E F23 45678 G?@: D375@>H = δ 011 = 01I 011 MQ11EKQ0 IIQ0 = 2.33% O > 2% Degradatin! 115 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC EXAMPLE 2 116 Traffic Academy - Interchange Studies
CONSTRAINED TRAFFIC EXAMPLE 2 117 Traffic Academy - Interchange Studies
TYPES OF MITIGATION Gemetric Cnstraints Limiting capacity imprvements Eliminating free flw (unsignalized) mvements 118 Traffic Academy - Interchange Studies
TYPES OF MITIGATION Variable Lane Assignment ATDM Ramp Metering Typically preferred t be applied n a crridr wide basis Need t cnsider ramp strage Need t prvide letter f cmmitment frm lcal enfrcement agency FHWA Ramp Management and Cntrl Handbk, January 2006 can be fund at: http://ps.fhwa.dt.gv/publicatins/ramp_mgmt_handbk/manual/manual/ 119 Traffic Academy - Interchange Studies
TURN LANE STORAGE Turn lane strage is determined by ODOT L&D Figures 401-9 & 401-10 (example included) Turn lanes n the arterial/crssrad shuld accunt fr strage + deceleratin (when applicable) Check fr thru blckage Turn lanes alng the exit ramps shuld be based n strage, it is assumed that deceleratin has already ccurred upstream f the gre. 120 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 1 Determine EBL Turn Lane Length: 121 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 1 Speed Limit = 50mph Design Speed = 55mph Cnditin B: Turn lane length = 285 (decel + 50 taper) 122 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 1 EBL Turn Lane = Decel + Strage = 165 + Strage 123 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 1 Average Vehicles per Cycle = DHV * Cycle Length 3600 sec/hr (345 veh/hr) (90 sec/cycle) 3600 sec/hr = 8.6 veh/cyc rund t 9.0 veh/cyc Strage = 350 EBL Turn Lane = Decel + Strage = 165 + 350 = 515 124 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 1 Determine EBL Turn Lane Length: Cnditin B = 285 Cnditin C = 515 515 > 285, s use 515 Hwever, we need t check fr thru blckage. 125 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 1 Average Vehicles per Cycle = DHV * Cycle Length 3600 sec/hr EBT = 1130 veh/hr (fr 2 lanes), 565 veh/hr/lane (565 veh/hr) (90 sec/cycle) 3600 sec/hr = 14.1 veh/cyc rund t 15.0 veh/cyc EB Thru Queue = 525 EB Left = 525 + 50 (taper) = 575 126 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 1 Determine EBL Turn Lane Length: Cnditin B = 285 Cnditin C = 515 Accmmdating Thru Blckage = 575 575 > 515, s use 575 525 strage + 50 taper 127 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 2 Determine NBL Turn Lane Lengths: 128 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 2 Design Speed = 35mph Cnditin A: Turn lane length = (50 taper + Strage) 129 Traffic Academy - Interchange Studies
TURN LANE STORAGE EX. 2 Average Vehicles per Cycle = DHV * Cycle Length 3600 sec/hr NBL + NBT = 650 + 5 = 655 veh/hr (fr 2 lanes) r 328 veh/hr/lane (328 veh/hr) (90 sec/cycle) 3600 sec/hr = 8.2 veh/cyc rund t 9.0 veh/cyc NB Left Turn Lanes = 350 Queue + 50 Taper = 400 130 Traffic Academy - Interchange Studies
TURN LANE STORAGE Turn Lane Length Summary 131 Traffic Academy - Interchange Studies
IOS REPORT CONTENT 132 Traffic Academy - Interchange Studies
IOS REPORT FORMAT/OUTLINE Prject Summary Study Area Prblem Descriptin Traffic Analyses Cnclusin Appendices and Exhibits Certified Traffic HCS Analyses Turn Lane Length Calculatins 133 Traffic Academy - Interchange Studies
ANALYSIS POINTS FOR IOS (1 INTERSECTION) Intersectin Analysis Nt Required * Intersectin Analysis Merge Analysis Diverge Analysis Mainline Analysis Next significant intersectin within ½ mile Weave Analysis (if applicable) * * Intersectin being mdified Certified Traffic Limits Obtain all cunts within limits 134 Traffic Academy - Interchange Studies
ANALYSIS POINTS FOR IOS (2 INTERSECTIONS) Next significant intersectin within ½ mile Intersectin being mdified * Intersectin Analysis Merge Analysis Diverge Analysis Mainline Analysis * * Next significant intersectin within ½ mile Weave Analysis (if applicable) 135 Traffic Academy - Interchange Studies * * Intersectin being mdified Certified Traffic Limits Obtain all cunts within limits
ANALYSIS POINTS FOR IOS (AUXILIARY LANE) * * Merge Analysis Diverge Analysis Mainline Analysis Weave Analysis Certified Traffic Limits Obtain all cunts within limits 136 Traffic Academy - Interchange Studies
IMS ADDENDUM 137 Traffic Academy - Interchange Studies
IMS ADDENDUM When is ne necessary? When a change is prpsed t the Build Cnditin as identified in an already apprved IMS. When cnstructin has nt cmmenced within 3 years f the apprval date f the IMS. This wuld require updating the traffic data t reflect the new Design Year. 138 Traffic Academy - Interchange Studies
IMS ADDENDUM Purpse T dcument the differences and assciated impacts between the Original Build Cnditin and the Revised Build Cnditin Nte: The cmparisn is nt between the N Build and the Revised Build. 139 Traffic Academy - Interchange Studies
IMS ADDENDUM Include: Reasn fr the change Cmparisn f the changes between the Original Build and Revised Build, such as, study area, updated traffic data, revised gemetry, revised access cnnectins, etc. 140 Traffic Academy - Interchange Studies
IMS ADDENDUM Include: The Levels f Service and HCS analyses based upn the Revised Build Cnditin A schematic f the Revised Build Cnditin and the Original Build Cnditin D Nt Include: The HCS analyses f the Original Build Cnditin 141 Traffic Academy - Interchange Studies
COMMON REVIEW COMMENTS 142 Traffic Academy - Interchange Studies
COMMON REVIEW COMMENTS Cnstructin plans being develped in advance f the IMS/IOS. The IMS/IOS is t serve as the blueprint fr the cnstructin plans, nt vice versa Nt using the mst updated versin f HCS, prviding unbalanced intersectins, r incrrect parameters (PHF, FFS, etc.,...) 143 Traffic Academy - Interchange Studies
COMMON REVIEW COMMENTS The text f the IMS shuld be succinct, but additinal discussin is warranted when smething is deficient r des nt meet requirements. Als, traffic cunts, envirnmental studies, traffic signal warrants shuld nt be included. 144 Traffic Academy - Interchange Studies
COMMON REVIEW COMMENTS Using nn-certified traffic in preliminary analyses and jumping t an alternative that ends up wrking with certified traffic in the IMS but a simpler/cheaper alternative may have been verlked Nt prviding a gd schematic f the build cnditin, with prpsed turn lanes clearly dimensined. 145 Traffic Academy - Interchange Studies
COMMON REVIEW COMMENTS Nt understanding when cnstrained traffic analyses are warranted and hw far t carry them Nt analyzing majr diverges crrectly r at all Turn lane length calculatins being hidden in spreadsheets, unable t fllw Cycle length used in analyses des nt match the cycle length used t calculate the turn lane length 146 Traffic Academy - Interchange Studies
TRAFFIC ACADEMY Office f Radway Engineering Dave Hlstein, P.E. Office Administratr 614-644-8137 Mary Bapu-Tamaskar, P.E. - Studies Engineer Districts 2, 3, 8 and 9 614-644-7888 Gary Harringtn, P.E. - Studies Engineer Districts 5, 6, 7 and 11 614-387-5205 Brentn Bgard, P.E. Studies Engineer Districts 1, 4, 10 and 12 614-752-5575 147 Traffic Academy - Interchange Studies