Network Attributes Calculator TRB Application Conference, Raleigh, NC May 15, 2017 Vipul Modi, Citilabs Inc. Greg Giaimo, Ohio DOT

Project Motivation Tasks included: Ohio Department of Transportation (ODOT) has been automatically calculating capacity and speed attributes using Highway Capacity Manual (HCM) procedures for travel demand model networks for 25 years which are used for both traditional link based and junction based assignment Tasks included: update procedures from HCM 2000 to HCM 2010 convert FORTRAN codes to Cube Voyager add roundabout capabilities expand stop-sign computations add freeway weaving adjustments expand geometrical aspects of networks

History First, created for Steubenville MPO networks in 1993 based on HCM 1985 procedures for consistence capacities values across networks for validation Updated to CAP94 program based on HCM 1994 procedures included several other MPO networks Updated to CAP2000 program based on HCM 2000 procedures used for networks in Ohio-Kentucky-Indiana region Ran as user-programs executables (.exe) in regional models

Components of Network Calculators Network Preparation Geometry Capacity Calculator Speed Calculator Turn Penalty File Writer Junction File Writer Final Outputs An external loop to process the data for different time periods

Current Network Calculators

Network Preparation conduct data consistency/completeness checks, flag inconsistent or incomplete network coding see next to see what conditions were flagged handle how the period specific over-ride attributes are used and how many times the outer loop should run if over-rides are not specified, default (daily) attributes are used write a network diagnostic summary file for the users’ reference

Network Preparation

Geometry this step determines the geometry of subject link by accessing link attributes from adjoining links step identifies the next intersection node or a conflict point conflict point is a node with > 2 links using a ‘downstream tracing algorithm’ used to carry over attributes of the intersection link to all links leading to subject link calculate distance between subject link and conflict point computes true shape angles between links used to obtain turn movements – left/through/right to be used in urban street capacity calculations

Geometry used to identify merging/diverging points for freeway merging analysis computes freeway weave length Obtains information on type of intersection, like two-way stops, four-way stops, roundabouts, or signals computes distance between two intersection nodes to calculate capacities If distance is >2 mile, then uncontrolled, if <2 mile, controlled

Capacity Calculator Process to calculate capacity values for network links old process computes capacities for freeway segments, multi-lane roads, rural highways, uninterrupted 2 lane facilities and interrupted urban segments using HCM 2000 procedures uses all necessary information like number of lanes, width, facility type, area-type, left/through/right lanes, parking lanes, etc coded in the network links or from the user-specified parameter file cross-street attributes obtained from geometry step to identify different type of urban street capacity calculations capacity computed for each time-period depending upon period-specific over-rides

Capacity Calculator current process includes HCM 2010 equations for basic freeway segment capacity calculations, multi-lane and two lane highways inclusion of total ramp density current process includes enhanced capacity values for two-way stop, four-way stop and roundabouts capacities computed in a spreadsheet with all possible scenarios using HCM 2010 methodologies based on geometric conditions, uses a lookup table to get the respective capacity values current process computes capacities for 5-link intersections virtually assuming a 4-link and 3-link intersections

Capacity Calculator current process includes freeway weaving analysis reduction factors are calculated that ‘reduces’ capacity due to weaving spill-over factors applied to upstream/downstream freeway links and ramps handles 4-link zero distance freeway-links

Speed Calculator old process updates base speeds on basis of link attributes and cross street attributes to obtain the final free flow or running speeds base speeds by facility type provided by ODOT current process incorporates free flow speed adjustments from Chapter 17 of HCM 2010 that uses area-type, distance between two consecutive signals (from geometry step), and two-way-left-turn lane coding speeds computed for each time-period depending upon period-specific over-rides two set of speeds based on total time and running time compute link groups for each link used in highway assignment used in selecting the volume delay function (VDF) for link flow speed adjustments

Turn Penalty Writer writes turn penalty files in {A-B-C-value-set} format append any existing turn prohibitions that the user provide use the geometry information to get all left-turn movements and give them a user-specified penalty value default turn penalty – 0.2 one turn penalty file for all time periods

Junction File Writer writes junction file for each node based on adjoining links information use of turn prohibitions for banning movements current process includes: new junction format based on HCM 2010 methodologies for two-way stops, four-way stops, roundabouts introduction of new signal phases split phasing based on link attributes forced left-turn phases or prohibition of left-turn phases write junction files for each time period

Final Outputs clean-up working network for the next loop (time period) and reset all temporary link attributes change attribute names for capacity, speeds, link group as per ODOT standards

Other… an outer loop to handle how many times the calculators should run based on over-ride link attributes capacities, speeds, linkgroups are computed for all AM, MD, PM and MD time periods flexible scenario manager to turn on/off following options: options to compute network utilities based on ‘old process’ or ‘new process’ options added to also use old format ODOT networks use of true-shapes in angle calculation managing output files parameter file (for default or user-over ride variables ) supplemented as external file

Software Additions (Cube Voyager) New Keywords added to NETWORK module

Software Additions (Cube Voyager) New Keywords added to NETWORK module

Software Additions (Cube Junction Model)

Moving forward… such automated network attribute computation from base attributes (LANES etc.) facilitates more detailed network operations modeling calculated values allow for both traditional VDF controlled link- based and more detailed junction based assignments transition to DTA much easier for ODOT as a result current enhancements continue the trend of adding more operational level detail in the planning networks

Acknowledgments Ohio Department of Transportation (ODOT) Greg Giaimo Rebekah Anderson

Questions/discussion