Simulation Based Assignment in PTV Visum - TRB 2017

www.ptvgroup.com

Michael Oliver, PTV Group

January, 2017

PTV VISUM 16: SIMULATION-BASED DYNAMIC ASSIGNMENT

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SIMULATION-BASED DYNAMIC ASSIGNMENT (SBA)

Distribute demand across

routes and time intervals

Network loading

Dynamic shortest paths per

OD and interval

Set of routes and costs per

OD pair and time interval

Demand per OD route and

time intervalDynamic network state

Update set of routes

Loop until Dynamic

User Equilibrium

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Network Loading:

Mesoscopic simulation used for network loading

Mesoscopic Simulation:

Uses the same science as in Mesoscopic simulation in

Simplified Car Following Model


Travel at desired speed unless impeded

Temporal distance (in seconds) =

reaction time + time it takes to travel

the standstill distance



Mesoscopic Simulation II:

Uses the same science as in Mesoscopic simulation in

Simplified Car Following Model

Lane Selection Model

Junctions modelled with signal control and gap acceptance

Realistic impact of signal offsets and coordination


Choice:

Lane enables next turning movement

Lane density



NETWORK MODELING FOR SBA

Permitted transport systems for

links, turns, and connectors

number of lanes, free-flow speed

junction control

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junction control

junction geometry









junction control

junction geometry

TSys parameters









junction control

junction geometry

TSys parameters

demand time series

7:006:00 8:00 9:00

Car

7:006:00 8:00 9:00

HGV









junction control

junction geometry

TSys parameters

demand time series

supply changes over time

7:30 – 8.00 a.m. 20 km/h





JUNCTION MODELLING FOR SIMULATION-BASED DYNAMIC ASSIGNMENT

Define for all nodes:

Lane turns and major movements

Signal timings and offsets

Gaps, if non-standard

Visum will derive conflicts and check gaps for lower

ranked movements



SIMULATION-BASED DYNAMIC ASSIGNMENT – OUTPUT ANALYSIS

Time Interval: 06:00-06:10












Standard outputs

• e.g. volumes, travel time & speed per analysis time interval

New for SBA

• Delay per analysis time interval

• Density

• Utilization

• Queue

• Simulation detail e.g. vehicles entered/exited





Showing all traffic that enters this link between 06:30 and 07:00

















New: Dynamic flow bundle

• Extract volumes in the network that use a particular

object(s) in a particular time interval

• Extract flow bundle matrices (OD demand that uses an

object at a particular time) by arrival and departure time

window

New: Dynamic skim matrices• Average, or arrival/departure time related indicators



Greater level of precision for demand

• Different hotspots at different times and in different places

• Suitable for larger networks represent effect of long-distance patterns such as

long-distance commutes

Greater level of precision for congestion

• Closer than ever to Vissim; the ideal stepping stone from Macro Micro

• Lane-level interactions influence the result, e.g. queueing

• Signal offsets realistically represented

Ideal use case for: heavily congested networks; transient congestion; time-

varying policies; incident/roadwork management; evacuation plans.

SIMULATION-BASED DYNAMIC ASSIGNMENT – SUMMARY


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Michael Oliver

PTV Visum Solution Director

[email protected]

http://vision-traffic.ptvgroup.com


mailto:[email protected]

http://vision-traffic.ptvgroup.com/

Engineering

Simulation Based Assignment in PTV Visum - TRB 2017