From Roader's Digest: The SABRE Wiki
|A LILO on the M50 near Newent.|
|Pictures related to LILO|
View gallery (9)
LILO (Left In Left Out) junctions are a low specification exit and entrance to a major road. They often feature on older dual carriageways where a GSJ was provided by building a bridge or underpass around an existing crossroads. They are found equally commonly where a minor road crosses a major route, or where it terminates on the major route. The sliproads, such as they are, can often be little more than a T junction, albeit only serving one carriageway of the major route. Traffic on the on and off slips are segregated by either a very small traffic island or simply hatched out tarmac as seen at perhaps the most infamous LILO example - M50 Junction 3 (pictured) near Newent. Generally speaking LILOs have slow down / acceleration lanes between the slips and the main route, but many are short and insufficient to deal with busy modern traffic levels. As such, many LILO junctions have seen some upgrading over the years, or even been closed off completely in favour of forcing traffic onto larger nearby junctions better able to cope with the traffic movements.
Newer LILO Junctions
In recent years, a number of at-grade junctions have been converted to a more modern variant of the LILO format to close the central reservation gap on a dual carriageway, and so make it safer. Whilst the original LILO junction design had two very tightly closed sliproads, safety concerns see the slips more widely spaced on modern junctions, and they are normally given a larger island to provide a safety margin between the sliproads. These, of course, are not strictly LILOs, but they are generally as close as is built today.
One example is the Kinfauns Junction on the A90 just east of Perth, with another very similar junction a little further east built at the same time. Also near Perth, the Bankfoot Junction on the A9 was adapted to LILO format by the addition of new sliproads on the southbound carriageway, despite the A9 itself still being S2 at this point.