How every number is worked out

Principles

• Facts from Street Manager. Every figure is built from permit and works records and can be traced to permit references.
• Estimates are labelled. S74 exposure is an estimate of what could be charged, not an invoice. We say so wherever it appears.
• Rules, not black boxes. Severity comes from fixed, published rules. No machine learning decides whether something is a clash.
• Emergency works are shown for what they are. Immediate works are a legal right. HighwayIQ excludes them from S74 overruns and shows the works category everywhere else.
• Changes are recorded. When a rule changes, this page changes and the date is shown below.

Clash severity

Each permit is checked by four detectors when a Street Manager event arrives for it. Each detector can raise one or more clashes, and each clash has one of four severities. A permit’s severity in the queue is its worst clash.

Blocking High Medium Low

“Live” works means not closed or completed, not refused, and not cancelled, unless work actually started under the cancelled permit. Dates use actual start and end where Street Manager has them, and proposed dates otherwise.

1. Spatial overlap with other works

Other live works within 30 m of this permit, with dates that overlap.

2. Section 58 restriction

The permit’s works area intersects an in-force restriction during the works dates. Always Blocking. See Section 58 checks.

3. Network impact

The works touch a protected route: a bus corridor, A-road or emergency service route.

4. Sensitive locations

The works are within the buffer distance of a sensitive location.

School sensitive hours (07:30–09:00 and 15:00–16:30) are shown with the clash so the coordinator can ask for works outside them. Buffers can be adjusted per authority.

Section 58 checks

Section 58 of the New Roads and Street Works Act 1991 lets a highway authority restrict works on a street after substantial roadworks, such as resurfacing.

A Section 58 clash is raised when all of these are true:

• The restriction’s status in Street Manager is in force. Proposed, cancelled and closed restrictions do not count.
• The restriction period overlaps the permit’s proposed dates.
• The restriction’s mapped extent intersects the permit’s works geometry, in British National Grid.
• The restriction belongs to the same highway authority as the permit.

Using the geometry rather than only the street reference (USRN) means a restriction covering part of a street catches works on that part only. A permit with no geometry can’t be checked spatially and is not flagged.

The legislation allows immediate (emergency and urgent) works on a restricted street. HighwayIQ shows the works category on every Section 58 alert so these can be dismissed with a note.

S74 overrun exposure

Section 74 of the Act allows a highway authority to charge a promoter for each day works overrun the agreed period.

When a works counts as overrunning

• The works has not been reported as complete, and the current time is past the deadline.
• The deadline is the end time given in Street Manager. If only a date is given, it is the end of that day, UK time, not the start of it.
• Immediate urgent and immediate emergency works are excluded.
• Works promoted by the highway authority itself are excluded, because an authority cannot charge itself.
• Each extension creates a new deadline. A breach of a later deadline is a separate alert.

The calculation

estimated charge = days over the deadline × daily rate

The daily rate depends on the street’s reinstatement category and whether it is traffic-sensitive:

Rates are applied per day. Where Street Manager sends a plain category 3 it is priced at the 3a rate, so exposure is never understated. Streets with no recognised category are priced at £0. Per-authority rate settings are planned.

Days remaining

The triage queue shows, for every live permit, the number of days from today to its proposed end date. Negative numbers mean the proposed end has passed. Combined with severity, it shows the coordinator what to look at first.

Network stress score

In development. Weights are being calibrated against live data and may change.

A weekly score per ward that reflects how much of the road network is disrupted at once.

1. Works weight = road category weight × traffic management weight × 1.5 if the street is traffic-sensitive.
2. Daily load = the sum of works weights for all works active in the ward that day. Each works counts once per day, at its highest-weighted permit.
3. Daily stress = daily load × (1 + 0.15 × (number of works active − 1)), so concurrent works compound.
4. Weekly score = the average daily stress over the seven days, Monday to Sunday.

The score is relative, not an absolute threshold: the heat map is coloured against the highest score in view. Future weeks include only permits already submitted, so they read lower than they will turn out.

Cross-boundary proximity

In development.

Pairs of works where one is yours and the other belongs to a different highway authority, within a set distance (100–500 m, chosen by the coordinator), and both are live on at least one shared day. This covers neighbouring councils across the boundary, and other authorities such as National Highways working inside your area. The same live-works rule as clash detection applies.

Data quality and limits

• Garbage in, garbage out. HighwayIQ is only as good as the Street Manager record. Imprecise works geometry or a wrong road category flows through to the result.
• Quarantine. Events with unparseable or impossible dates are held in quarantine for review rather than overwriting good data.
• No contractor data. Street Manager open data names the promoter, not the contractor who did the work. HighwayIQ attributes works to the promoter, who is the accountable party in law.
• Reference data is local. Sensitive locations and protected routes are loaded per authority from open data, and improve with local review.

Data sources

Street Manager open data (Department for Transport); ward and local authority boundaries (Office for National Statistics); OS Open Roads and OS Open USRN (Ordnance Survey); NaPTAN (Department for Transport); Get Information about Schools (Department for Education). All are used under the Open Government Licence v3.0. See open data and licences.

Methodology last reviewed 22 October 2026.