Municipal street light: class, spacing and the documents
A municipal scheme is procured against a calculation, so the work is to supply the calculation, the file behind it and the certificate that covers the model. Price is the last column in the comparison, not the first.
Specification
What the sheet states for this build, and what is confirmed per project.
| Topic | What the sheet states |
|---|---|
| Class | Set by the road, the traffic and the conflict areas |
| Calculation | Pole layout, height, overhang and tilt, at the maintenance factor |
| Distribution | Short, medium or long, symmetric or not |
| Back light | Limited where dwellings are close to the carriageway |
| Mounting | Side entry, post top or suspension, with the spigot size |
| Control | Dimming profile, often part of the tender |
| Certification | File per model and market, with scope and expiry |
| Surge protection | Class agreed for the site |
| Data sheet | Current revision, naming the delivered model |
The certificate is model specific. A file that covers a different model in the same family is not a certificate for what is being delivered, and a tender evaluation will check.
What the class does and does not say
The class fixes the level and the uniformity on the carriageway and the glare the scheme may present. It does not say where the poles go, how far they overhang or which distribution is used. Those are the designer's choices, and they are what the calculation proves.
This is why two compliant bids can look completely different. One uses fewer, taller poles with a long distribution; another uses more, shorter poles with a medium one. Both reach the class and they cost different amounts to install and to maintain.
- The class and the maintenance factor, quoted from the tender.
- The pole layout in the drawings, and whether it is fixed or optional.
- The overhang and the tilt the design assumes.
Back light, and the houses beside the road
A road light aimed across the carriageway also lights the front of the houses on the other side. Back light control, a flat glass optic and a correct overhang are the three things that reduce it, and they are specified rather than added.
Where the tender includes a light nuisance condition, ask for the back light figure in the photometric file and check it against the condition before the bid is priced.
- The distance to the nearest dwelling, and any nuisance condition.
- The back light figure from the file, not from the brochure.
- Whether the optic can be rotated to suit the side of the road.
Fifteen years, not one night
A road scheme is judged over its life. The luminaire has to be reachable by the authority's lift, its driver replaceable in the field, and its model still available when a section is extended in year six. Those are contract questions, and they are asked before the award.
The other lifetime item is surge. A pole in an open verge is a lightning target, and a scheme that skips the surge class saves a small amount once and loses a driver per storm.
- The access equipment the authority uses, against the mounting height.
- A written spares and availability statement.
- The surge class in the specification, and the test behind it.
Before the order
- Calculation, file, certificate: the three documents a bid is evaluated on.
- Delivered model code, so the data sheet, the carton and the certificate match.
- Spares and availability in writing, for the life of the scheme.
- Build
- Municipal street light
- Line
- Street lights
- Ask for
- Specification sheet, photometric file, aiming drawing
Send the space, get the sheet.
Build, specification sheet and the option list for each line item, in one reply.