An offline-first app for field engineers

The problem

Fernway's 85 field engineers inspect and replace water meters across a mostly rural region. Each visit produced a paper form and a handful of photos on a personal phone. Office staff typed the forms into the asset system, usually three to five days later. Around 9% of forms had a missing or unreadable meter serial, which meant a second visit.

A previous tablet app had failed because it needed a connection to load each job, and a third of the region has no reliable signal. Engineers went back to paper within a month. The brief to us was blunt: if it does not work in a basement with no bars, do not bother. It also had to run on the mid-range Android phones the company had already bought.

Process

1. 01

   Offline is the default state

   We treated connectivity as a bonus. Each morning the app downloads the engineer's jobs, asset history and form definitions into SQLite on the device. Every action writes locally first. A sync queue pushes changes when a signal appears, with photos uploaded separately in the background so a slow connection never blocks a form submission.

2. 02

   Conflicts with clear rules

   Two people occasionally touch the same asset, for instance when office staff update an address while an engineer is on site. We avoided a general merge algorithm and wrote field-level rules with the operations team: site readings always win from the field, contact details always win from the office. Anything else lands in a small review list.

3. 03

   Scan instead of type

   Most data errors came from copying long serial numbers by hand. We added barcode scanning for meter serials with on-device recognition, plus range checks on readings that flag a value wildly different from the last visit. We chose React Native so the office web app and the mobile app could share validation code in TypeScript.

Selected images

Outcome