Differences in terminology are especially obvious in the context of roads. The British term "dual carriageway", in American parlance, would be "divided highway" or perhaps, simply "highway". The "central reservation" on a "motorway" or "dual carriageway" in the UK would be the "median" or "center divide" on a "freeway", "expressway", "highway" or "parkway" in the US. The one-way lanes that make it possible to enter and leave such roads at an intermediate point without disrupting the flow of traffic are known as "slip roads" in the UK but in the US, they are typically known as "ramps" and both further distinguish between "on-ramps" or "on-slips" (for entering onto a highway/carriageway) and "off-ramps" or "exit-slips" (for leaving a highway/carriageway). When American engineers speak of "slip roads", they are referring to a street that runs alongside the main road (separated by a berm) to allow off-the-highway access to the premises that are there; however, the term "frontage road" is more commonly used, as this term is the equivalent of "service road" in the UK. However, it is not uncommon for an American to use "service road" as well instead of "frontage road".