# Fix the worst first, or keep good roads good?

*The road that draws the most complaints is rarely the best use of the next dollar. The evidence for treating roads while they are still in fair shape is strong, but it is mostly American and decades old, so test it on your own network before you lean on it.*

## Two ways to spend the same budget

**Worst first** sends money to the roads in the poorest condition. It is easy to explain and it answers the complaints that reach councillors.

**Preservation first** spends part of the budget on cheaper treatments, such as crack sealing, resealing or thin surfacing, applied to roads that are still structurally sound, so they stay in good condition longer. The rest goes to the worst roads.

The idea is summed up by a phrase from US maintenance practice: the right treatment, on the right road, at the right time.

## What the evidence says

Most published evidence comes from US state and city agencies in the 1990s, collected in a 1999 Federal Highway Administration and National Highway Institute course. Treat the figures as US evidence, in US dollars of the time:

- **Treatment costs differ by an order of magnitude.** The City of Bedford, Texas, reported microsurfacing a lane-mile of good road for $10,270, minor rehabilitation for $45,570, and reconstruction of a failed lane-mile for $574,000.
- **Michigan** reported rehabilitation and reconstruction costing about 14 times as much per lane-mile as preventive maintenance.
- **New York State** compared five years of worst-first against preventive maintenance for the same funding; the preventive strategy left a much larger share of the network in good condition.
- **A Wisconsin local-roads simulation** compared six strategies on a 400-mile network with a fixed budget. Apart from an unlimited budget, the best result came from applying preventive maintenance first and spending the remainder on the worst roads.

Two cautions from the same source. First, the familiar chart showing $1 of early treatment saving $4–5 later is an idealised picture, not a measurement. Second, preventive treatments placed on roads that are already too far gone can fail early. A field programme found that slurry or chip seals on heavily aged pavements accelerated failure. Timing is the whole point.

## Why worst-first persists

The same course is frank about the obstacle: an agency is much more likely to hear about the failed road in front of someone's house than about the overall condition of the network. Spending on roads that look fine can be hard to defend in a public meeting.

The agencies that made the change did it by showing their own data. New York compared both strategies on its own network data; California projected its network under an aggressive preventive programme and secured additional funding on the strength of it. Bedford showed its council two spending patterns for the same total money and won an additional sales tax to fund the programme. A projection of your own network is more persuasive than any national statistic.

They also found that preservation only works with steady funding. When New York's programme was delayed, treatments were either applied late, when they were no longer suitable, or deferred to the next season.

## Testing it on your own network

1. Project your network five or ten years ahead at your current budget, spending worst first.
2. Project it again at the same budget with a share set aside for treating fair roads.
3. Compare the ending condition, the length in poor condition and the backlog of unfunded work.
4. Present both to councillors with the assumptions in plain view.

## How PaveKeep handles this

PaveKeep shows what a budget buys over a chosen number of years: which roads get done, what condition the network ends up in, and what a different budget would have bought instead. Its five- and ten-year projections show the cost of doing nothing. Each recommended road comes with the reason it is on the list, so a councillor can see why a fair road is being treated ahead of a poor one.

PaveKeep is built for small and regional councils and is not yet in use at any council.

## Sources

- Federal Highway Administration and National Highway Institute (1999), *Pavement Preservation: The Preventive Maintenance Concept, Executive Overview*, FHWA-HI-00-006, NHI course 13154. Includes the Bedford, Michigan, New York, Wisconsin and SHRP findings cited above.

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Source: https://pavekeep.com.au/knowledge/worst-first-or-keep-good-roads-good · PaveKeep · bound content