Traffic Analy​​sis

DOTD uses an integrated, systematic and performance based approach to traffic engineering.  For our intersection control evaulation policy, please see EDSM VI.1.1.2 Intersection Control Evaluation (ICE) Requirements.  

The following definitions are provided for clarification purposes: 
  • ​​​​​​​​Traffic Signal Upgrade:  Work which involves any one of the following for non-emergency purposes; the installation of a new controller and cabinet, rewiring the entire signal, installing all new poles or changing the layout of the signal.
  • Restricted Crossing U-Turn (RCUT):  Intersection is defined as a non-traditional intersection system that utilizes a combination of one partial median opening and two directional median openings.  This type of intersection is typically the crossing of major and minor arterials where the left turn moves are relatively high.  The openings must be appropriately spaced with one directional u-turn opening or one partial median opening on each side of the partial median opening.  The distance between two of these systems is also critical.  The intersection and u-turns may be unsignalized or signalized, depending on volumes.  
  • Median U-Turn (MUT) Intersection:  Intersection is defined as the use of two or four directional u-turn openings, placed on each side of an intersection, combined with the prohibition of all left turns at the intersection.  This type of intersection is typically the crossing of two major arterials where the through move is heavier than the left turns. All through movements and right turns at the intersection are permitted.  The openings must be appropriately spaced with one directional median opening on each side of the partial median opening.  The distance between two of these treatments is also critical.  The main intersection is typically signalized and the u-turns may be unsignalized or signalized, depending on volumes.   
  • ​Full Access Traffic Signal:  A traffic signal where all approaches are allowed to turn left out and left in.

Software Resources​

  
  
  
  
LACalibration.pdfLACalibration4/25/2017 12:47 PM128 KB
Microsimulation Policy.pdfMicrosimulation Policy11/7/2019 3:24 PM414 KB
Sidra Settings Brochure.pdfSidra Settings Brochure4/10/2019 8:11 AM299 KB
Traffic Analysis Software Selection.pdfTraffic Analysis Software Selection11/7/2019 3:24 PM341 KB
Vehicles.zipVehicles4/25/2017 12:46 PM10286 KB
 
Tier 1 Analysis Tools

DOTD Approved Traffic Software

    • HCS
    • Sidra
    • Vissim - Only tool allowed for microsimulation 

 

LADOTD uses the HCM (Highway Capacity Manual 6th Edition) for traffic analysis methods and equations.  HCS (Highway Capacity Software) will only be allowed for the equations that are in the HCM and cannot be tweaked to provide output for solutions that are not in the HCM.  For conditions, limitations or other scenarios that cannot be addressed with HCS, approval shall be obtained before utilizing other software.  Using travel time as an MOE and oversaturation are two examples that need approval to use macroscopic or mesoscopic software.  For questions or concerns, please contact the Traffic Engineering Division Administrator at TrafficEngineering@la.gov.

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