Diamond Intersection:
A diamond intersection is a type of road junction where two roads intersect at the same elevation, forming a diamond shape. This type of intersection typically includes signalized or controlled access points for turning movements. It is called a diamond intersection because when viewed from above, the layout of the roads resembles the shape of a diamond.

Unchannelised Intersection:
An unchannelised intersection is a type of road junction where two or more roads intersect without any physical separation or guidance for turning movements. Vehicles approaching the intersection are free to move in any direction without any designated lanes or traffic control measures. This type of intersection is typically found in rural or low-traffic areas where traffic volumes are relatively low.

Channelised Intersection:
A channelised intersection is a type of road junction where turning movements are guided and controlled by designated lanes or channels. This type of intersection typically includes painted lane markings, traffic signals, or physical barriers to separate different streams of traffic. Channelisation helps to improve safety and efficiency by providing clear guidance for turning movements and reducing conflicts between vehicles.

Roundabout:
A roundabout, also known as a traffic circle or rotary, is a type of road junction where traffic flows in a circular pattern around a central island. Vehicles entering the roundabout must yield to those already circulating and choose the appropriate exit when approaching their desired destination. Roundabouts are designed to improve traffic flow, reduce congestion, and enhance safety by eliminating conflict points and reducing the severity of potential collisions.

Answer:
Among the given options, the unchannelised intersection is not a road junction at the same elevation. Unlike the other options, an unchannelised intersection does not have any designated lanes or traffic control measures to guide turning movements. Vehicles approaching an unchannelised intersection have the flexibility to choose any direction without any physical separation or guidance. This type of intersection is typically found in rural or low-traffic areas where traffic volumes are relatively low.