For a third-order, class I and II geodetic control network, station spacing in traverse should not be less than:

• A. 0.25 km
• B. 0.50 km
• C. 0.75 km
• D. 1.00 km

Answer: (B)

The key idea here is how far apart stations should be placed in a traverse so that observational errors don’t accumulate too much while keeping field work practical. For a third‑order, class I and II geodetic control network, the geometry of the traverse needs enough short length to keep distance and angle errors from piling up along a long line, but not so many stations that the extra measurements add little real improvement and waste time.

Half a kilometer as the minimum spacing provides this balance. It ensures each leg is short enough to limit error propagation between successive stations, helping the least‑squares adjustment distribute errors wisely and keep misclosures within the required tolerances. If stations were placed closer than this, the field effort would rise without a proportional gain in accuracy, and the error structure would become overly correlated among many nearby legs. If spacing were allowed to grow well beyond this, errors could propagate farther along longer legs, compromising the network’s precision for a third‑order class I/II network.

So, the minimum allowable traverse station spacing is half a kilometer.