THE EDITOR, Madam: A newly repaired road is welcome news, but it is not the end of the story. The real test comes later, when traffic, rainfall and everyday use demonstrate how well the road performs. As SPARK moves into its main-road phase, the roads already completed can provide useful lessons for the 37 main roads ahead. Beneath the road are layers of material that support traffic. The strength of the underlying ground, construction quality, drainage, traffic loads and maintenance can all affect how long a road remains in good condition.