These Traffic Modelling Guidelines, produced by the Traffic Directorate within TfL Streets, provide overarching guidance on the appropriate standards of traffic modelling required when proposing a traffic signal scheme on London’s urban network.
Modelling experts within TfL and across the industry have contributed to this document.
Part A provides a high level overview of traffic modelling for a non-technical audience, whilst Part B presents specific advice and standards for practitioners. The document can be read as a whole entity, but can also be used as a reference for particular traffic modelling issues.
The content of these guidelines was correct at the time of publishing, based on versions of software that were in everyday use in TfL TD. Since traffic modelling software vendors are continually developing new versions of their software, the intention is to treat this document as an evolving entity. It will continue to be updated in the future to provide best practice advice on new products, concepts and techniques as they are developed and tested in our working environment.
All advice provided in the Traffic Modelling Guidelines is non-binding but is directly related to the way TfL operates London’s traffic management systems. This document builds upon the success of the two previous versions, which have been used as guidance during the development of numerous traffic models both in the UK and overseas.
The latest version of this document is available to download from:
http://tfl.gov.uk/streetspublications
We encourage feedback on the advice given in this document. Please address all comments, specifying that they are related to the Traffic Modelling Guidelines Version 3.0, to:
TfL Traffic Modelling Guidelines, Network Performance,
Traffic Directorate, Surface Transport, Transport for London,
3rd Floor, Palestra,
197 Blackfriars Road, LONDON,
SE1 8NJ.
GLOSSARY
AIMSUN Advanced Interactive Microscopic Simulator for Urban and non-urban Networks, modelling software developed by TSS
ANPR Automatic Number Plate Recognition AQMA Air Quality Management Area
ARCADY Assessment of Roundabout Capacity And DelaY, modelling software developed by TRL
ASL Advanced Stop Line (for cyclists)
BP Bus Priority
BR&P Better Routes and Places Directorate, formerly the London Road Safety Unit
CE Checking Engineer, key role identified in MAP
CFP Cyclic Flow Profile
CLF Cableless Linking Facility
COBA COst Benefit Analysis, described in the DMRB
CTM Cell Transmission Model, new traffic model introduced in TRANSYT v13 in addition to PDM
CYOP CYcle time OPtimisation, a TRANSYT feature used to select an appropriate cycle time for a modelled network
DE Design Engineer, key role identified in MAP DfT The Department for Transport
DMRB Design Manual for Roads and Bridges
DoS Degree of Saturation
DSD Desired Speed Decision (used in VISSIM modelling)
EQUISAT A TRANSYT feature that provides an initial set of signal timings prior to optimisation, based on equal saturation of critical conflicting links FlowRound Software for the analysis of spiral traffic lane movements at
signalised and unsignalised roundabouts, developed by JCT FPT Forward Planning Team, formerly Network Assurance Team GIS Geographic Information System
GLA Greater London Authority
HCM Highway Capacity Manual
HGV Heavy Goods Vehicle
HTA Highway Traffic Assignment
ICA Intersection Capacity Analysis (used in VISUM modelling) ITS Institute for Transport Studies, University of Leeds JCT JCT Consultancy Ltd, developer of FlowRound,
LinSat, LinSig and TranEd
LCAP London Congestion Analysis Project
Legion Pedestrian modelling software, developed by Legion Ltd
LGV Light Goods Vehicle
LinSat Freely available software developed by JCT, allowing the estimation of effective flare usage based on flow data LinSig Modelling software developed by JCT
LSTCC London Streets Traffic Control Centre (within TD) LTA Local Traffic Authority
LTS London Transportation Studies, strategic model MAE Model Auditing Engineer, key role identified in MAP
MAP Model Auditing Process
MGV Medium Goods Vehicle
MME Mean Modulus of Error
MMQ Mean Maximum Queue
MOVA Microprocessor Optimised Vehicle Activation MUC Multiple User Class (assignment)
NAE Network Assurance Engineer, key role identified in MAP NAQS National Air Quality Strategy
NMD Network Management Duty (see TMA) NMG TfL Surface Network Management Group NP Network Performance (within TD), formerly
Urban Traffic Control (UTC) O/D Origin-Destination (matrix) ONE Operational Network Evaluator
OS Ordnance Survey (Mapping)
OSCADY PRO Optimised Signal Capacity And Delay: Phase-based Rapid Optimisation, modelling software developed by TRL P Promoter, key role identified in MAP
PI Performance Index, a monetary value used in TRANSYT to assess the cost of stops and delays in a network PICADY Priority Intersection Capacity And DelaY,
modelling software developed by TRL
PCU Passenger Car Unit
PDM Platoon Dispersion Model, the traditional traffic model used in TRANSYT
PRC Practical Reserve Capacity
.PRT Output file produced by TRANSYT detailing model results
PTV Planung Transport Verkehr (PTV) AG, developer of VISSIM and VISUM QueProb TRANSYT feature allowing the estimation of
effective flare usage based on flow data RD TfL Streets Road Directorate
RR67 Research Report 67, publication by TRL describing a methodology for the prediction of saturation flows RSA Reduced Speed Area (used in VISSIM modelling) SAE Signals Auditing Engineer, key role identified in MAP
SAFENET Software for Accident Frequency Estimation for NETworks, accident modelling software developed by TRL
SASS System Activated Strategy Selection
SATURN Simulation and Assignment of Traffic to Urban Road Networks, modelling software suite developed by ITS SCOOT Split, Cycle and Offset Optimisation Technique, developed
by TRL
SLD Site Layout Drawing
SQA-0064 TfL TD Document, Technical Specification SQA-0064, containing Design Standards for Signal Schemes in London (formerly ‘TTS 6’)
SRN Strategic Road Network
SUE Stochastic User Equilibrium (assignment) SVD Selective Vehicle Detection
TD TfL Streets Traffic Directorate, formerly Directorate of Traffic Operations (DTO)
TI Traffic Infrastructure (within TD)
TfL Transport for London
TLRN Transport for London Road Network TMA Traffic Management Act 2004
TMAP TRANSYT Model Auditing Process (see MAP)
TranEd Software developed by JCT to provide an improved graphical user interface for TRANSYT versions 12 and earlier
TRANSYT TRAffic Network StudY Tool, modelling software developed by TRL TRL Transport Research Laboratory (TRL Ltd), developer of ARCADY,
OSCADY PRO, PICADY, SAFENET, SCOOT and TRANSYT TSS Transport Simulation Systems, developer of AIMSUN TSSR Traffic Signal Supplementary Report
UDA User-Defined Attribute (used in VISUM modelling)
UGT Underutilised Green Time
UTC Urban Traffic Control
VA Vehicle Actuation
VAP Vehicle Actuated Programming (used in VISSIM modelling) VDF Volume-Delay Function (used in strategic/HTA modelling) VISSIM Verkehr In Städten – SIMulation (meaning: Traffic In Towns
– SIMulation), modelling software developed by PTV VISUM Verkehr In Städten – UMlegung (meaning: Traffic In Towns
– Assignment), modelling software developed by PTV VMAP VISSIM Model Auditing Process (see MAP)
WebTag DfT Transport Analysis Guidance