SIDRA INTERSECTION 11
NETWORK MODELLING
Lane-LevelNetwork Analysis

Queues form lane by lane in the real world — the SIDRA network model captures what link-based tools aggregate away.

Queue Spillback,Modelled Explicitly

When a downstream queue blocks an upstream lane, capacity is reduced — identified at the individual lane level, not approximated.

Signal Coordinationby Movement Class

Second-by-second platoon tracking, Offset optimisation, and Common Control Groups — with no equivalent in competing analytical tools.

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In a link-based model, the performance of individual lanes is lost in aggregation. But queues form lane by lane in the real world, and the capacity and congestion effects that drive gridlock — a blocked right-turn bay, a short lane that overflows, a downstream queue that spills back into an upstream through lane — all occur at the lane level.

Lane-level resolution
Individual queues, capacities and blockage effects modelled at the lane level — not aggregated to lane groups or links.
Deterministic results
Same inputs, same outputs, no stochastic variation — results are reproducible and auditable.
Analytical speed
Network results in seconds, not hours — enabling rapid scenario testing and design iteration.

When a downstream queue blocks an upstream lane, capacity is reduced — identified at the individual lane level, not approximated. The network model propagates these effects across up to 50 Sites.

Lane blockage
The model identifies which upstream lanes are blocked by which downstream queues and calculates the resulting capacity reduction, including dynamic saturation flow adjustment with corresponding effect on signal timing calculations.
Capacity constraint
Oversaturated upstream lanes are constrained so that exit flow rates entering downstream lanes are limited to capacity flow rates — arrival flow rates differ from demand flow rates.
Iterative convergence
Lane blockage and capacity constraint have opposing effects. A network-wide iterative process finds the solution that balances them.

The lane configurations that cause real-world congestion — short turn bays that overflow, shared lanes where one movement blocks another, merge points where two streams compete — all require lane-level modelling to analyse properly.

Short lane model
Complex multiple short lane configurations (turn bays, lanes with upstream parking, exit-side lane drops) where overflow from a short lane blocks adjacent full-length lanes.
Shared lane model
Movements with different signal control characteristics sharing a lane, where one movement blocks another (modelled using the free queue method).
Merge model
Exit short lane merge at any intersection type, with Priority Merge and Zipper Merge operations.
Continuous lanes
Uninterrupted flow modelling with detailed performance estimates for midblock segments.
U-Turns
Modelled at all Site types, including U-Turn before intersection at signalised and unsignalised Sites.

For signalised Sites in Networks, SIDRA INTERSECTION generates lane-based, second-by-second platoon arrival and departure patterns by Movement Class. Midblock lane changes are applied to these patterns — critical for closely-spaced intersections.

Network signal timing
Cycle time, phase times and signal Offsets calculated across the network, with Offset optimisation for corridor progression.
Common Control Groups
Multiple intersections under a single controller — a capability unique to SIDRA among analytical tools.
Interactive Offsets
Graphical adjustment of signal coordination with Time-Distance displays for two-way progression analysis.
Downstream bunching effects
For roundabouts and sign-controlled intersections downstream of signals, the model determines the extra bunching caused by upstream signal releases — reducing gap-acceptance capacity at the downstream unsignalised Site.

Pre-built templates for common intersection and network configurations eliminate manual geometry setup — select a template, adjust the parameters, and analyse.

Site Templates
18 roundabout configurations, signalised intersections with various leg and lane configurations, sign-controlled intersections, pedestrian crossings.
Network Templates
Paired intersections, freeway interchanges (single-point, diamond, DDI), innovative designs (RCUT, CFI, DLT, MUT, P-Turn, Divergabout), staged pedestrian crossings, roundabout corridors.
Map Extract
Create new Sites from map data — geometry and lane configurations generated directly from the map for immediate use.

Define routes through the network to report travel time, speed and delay broken down by component — also used for signal offset calculations to optimise two-way progression along corridors.

Five delay components
Intersection delay, geometric delay (approach and exit), midblock delay, queuing delay (including spillback effects), and stop delay.
Comprehensive output
Level of Service, delay, queue length (average and percentile), back of queue, stop rate, travel time, speed, fuel consumption, emissions and operating cost.
Signal offset optimisation
Routes provide the basis for optimising signal Offsets to achieve two-way progression along corridors, with Time-Distance displays showing platoon movement.

Lane-based,
not link-basednot link-level approximation

Most analytical tools treat each intersection in isolation. Microsimulation captures spillback but at significant computational cost. The SIDRA INTERSECTION Network model captures these effects analytically, at the lane level, with deterministic and reproducible results.

In a link-based model, the performance of individual lanes is lost in aggregation. But queues form lane by lane in the real world, and the capacity and congestion effects that drive gridlock — a blocked right-turn bay, a short lane that overflows, a downstream queue that spills back into an upstream through lane — all occur at the lane level.

Lane-level resolution
Individual queues, capacities and blockage effects modelled at the lane level — not aggregated to lane groups or links.
Deterministic results
Same inputs, same outputs, no stochastic variation — results are reproducible and auditable.
Analytical speed
Network results in seconds, not hours — enabling rapid scenario testing and design iteration.

Queue spillback and backward congestion spreadwhen downstream queues block upstream lanes

Short lane queues overflowing into adjacent full-length lanes, exit blockage effects, and back of queue extending upstream at intermediate locations with continuous lanes.

When a downstream queue blocks an upstream lane, capacity is reduced — identified at the individual lane level, not approximated. The network model propagates these effects across up to 50 Sites.

Lane blockage
The model identifies which upstream lanes are blocked by which downstream queues and calculates the resulting capacity reduction, including dynamic saturation flow adjustment with corresponding effect on signal timing calculations.
Capacity constraint
Oversaturated upstream lanes are constrained so that exit flow rates entering downstream lanes are limited to capacity flow rates — arrival flow rates differ from demand flow rates.
Iterative convergence
Lane blockage and capacity constraint have opposing effects. A network-wide iterative process finds the solution that balances them.

Where congestion occursshort lanes, shared lanes, merges

Link-based models that aggregate to lane groups cannot identify these effects — let alone quantify the design changes needed to resolve them.

The lane configurations that cause real-world congestion — short turn bays that overflow, shared lanes where one movement blocks another, merge points where two streams compete — all require lane-level modelling to analyse properly.

Short lane model
Complex multiple short lane configurations (turn bays, lanes with upstream parking, exit-side lane drops) where overflow from a short lane blocks adjacent full-length lanes.
Shared lane model
Movements with different signal control characteristics sharing a lane, where one movement blocks another (modelled using the free queue method).
Merge model
Exit short lane merge at any intersection type, with Priority Merge and Zipper Merge operations.
Continuous lanes
Uninterrupted flow modelling with detailed performance estimates for midblock segments.
U-Turns
Modelled at all Site types, including U-Turn before intersection at signalised and unsignalised Sites.

Signal coordination with second-by-second platoon trackinglane-based patterns by Movement Class

Second-by-second platoon tracking, Offset optimisation, and Common Control Groups — with no equivalent in competing analytical tools.

For signalised Sites in Networks, SIDRA INTERSECTION generates lane-based, second-by-second platoon arrival and departure patterns by Movement Class. Midblock lane changes are applied to these patterns — critical for closely-spaced intersections.

Network signal timing
Cycle time, phase times and signal Offsets calculated across the network, with Offset optimisation for corridor progression.
Common Control Groups
Multiple intersections under a single controller — a capability unique to SIDRA among analytical tools.
Interactive Offsets
Graphical adjustment of signal coordination with Time-Distance displays for two-way progression analysis.
Downstream bunching effects
For roundabouts and sign-controlled intersections downstream of signals, the model determines the extra bunching caused by upstream signal releases — reducing gap-acceptance capacity at the downstream unsignalised Site.

Site and Network Templatescomplete geometry in seconds

The modeller adjusts volumes, phasing and geometry — from template to results in minutes, not hours.

Pre-built templates for common intersection and network configurations eliminate manual geometry setup — select a template, adjust the parameters, and analyse.

Site Templates
18 roundabout configurations, signalised intersections with various leg and lane configurations, sign-controlled intersections, pedestrian crossings.
Network Templates
Paired intersections, freeway interchanges (single-point, diamond, DDI), innovative designs (RCUT, CFI, DLT, MUT, P-Turn, Divergabout), staged pedestrian crossings, roundabout corridors.
Map Extract
Create new Sites from map data — geometry and lane configurations generated directly from the map for immediate use.

Routes for travel time and performancefive delay components in every calculation

Each route decomposes travel time into five distinct delay components — giving practitioners visibility into where time is lost and why.

Define routes through the network to report travel time, speed and delay broken down by component — also used for signal offset calculations to optimise two-way progression along corridors.

Five delay components
Intersection delay, geometric delay (approach and exit), midblock delay, queuing delay (including spillback effects), and stop delay.
Comprehensive output
Level of Service, delay, queue length (average and percentile), back of queue, stop rate, travel time, speed, fuel consumption, emissions and operating cost.
Signal offset optimisation
Routes provide the basis for optimising signal Offsets to achieve two-way progression along corridors, with Time-Distance displays showing platoon movement.

Micro-analytical
traffic assignment

Everything on this page — lane-level precision, queue spillback, signal coordination, route performance — feeds directly into SIDRA ASSIGN. It is the only traffic assignment tool built on a micro-analytical Network model.