Road Junctions, Widening and Turning Lanes in AutoCAD
Last updated 24 October 2026
Join a new road to an existing one with kerb returns and an auxiliary lane, add a lane between two chainages and taper a road, with RoadPro's RDJ, RDW and RDT.
These commands work on a road already drawn with RoadPro (see how to draw a complete road from a centre line). Chainages can be typed as 100 or 0+100.
A junction: RDJ
RDJ joins a new road to an existing RoadPro road. Start the branch's centre line on the main road's centre line, away from any widened or tapered edge, and RoadPro forms the junction:
- kerb returns with the radius you choose, and the main road's edge opened between them;
- the corner surface, and the corner treatment: barricades, traffic cones or kerb stone, or the same as the main road;
- STOP or GIVE WAY and the turning-area markings;
- optionally an auxiliary (turning) lane: a long approach taper, a storage length and a short departure taper;
- optionally a kerbed or painted splitter island.
RoadPro warns if a lane beside the island would be narrower than 2.75 m: make the island narrower or the branch road wider. The report lists the kerb returns' TC, IP and CT with their coordinates.
An extra lane between two chainages: RDW
RDW widens the road for a stretch and brings it back, with straight or curved tapers at each end. Each side can have its own chainages and radius, and the barricades, cones or kerb stone move out to the new edge. The start must be at least the taper-in length along the road, and the end plus the taper-out must stay within the road.
A permanent change of width: RDT
RDT makes the road wider (+) or narrower (−) between two chainages, and the new width carries on to the road end. As with RDW, each side can differ and the edge treatment follows the new edge.
The defaults
| Item | Default |
|---|---|
| Widening / taper | 3.65 m / 30 m |
| Auxiliary lane | 3.65 m, tapers 60 m / 30 m, storage 30 m |
| Junction corners | Same as the main road edge |
Markings and a single line of barricades
- RDM redraws the markings after a junction or widening: gaps at junctions and a broken line beside auxiliary lanes. Run it again to refresh, or to remove them.
- RDL places one run of barricades, traffic cones or kerb stone along any line, polyline, arc or circle, on the line or to either side, between two distances, with a quantity label. It needs no road, so it suits a site boundary or a work zone. If it places nothing, the From / To distances are outside the line or the spacing is longer than it.
Quantities
Junctions, widenings and tapers are in the report with their new edge offsets and areas, so the quantities stay right. See road quantities and setting-out data from AutoCAD to Excel.
Draw your next road with RoadPro