Editing Single-point urban interchange (section)

===Disadvantages===
The major disadvantage of SPUIs over other types of road junctions is the increased cost due to the need for a longer or wider bridge. A freeway-under SPUI (as in the upper diagram) requires a wider bridge over the free-flowing road to make room for the compressed on- and offramps. However, this disadvantage poses less of a problem in cases where the arterial, or nonfreeway road, already requires a very wide bridge. The intersection of [[97 Street, Edmonton|97 Street]], having seven throughlanes, with [[Alberta Highway 16|Yellowhead Trail]] in [[Edmonton]], Alberta, Canada, though a diamond interchange in concept, required such a wide bridge that traffic-signal phasing allows this intersection to behave as a SPUI. A freeway-over SPUI (as in the lower photo) requires a longer bridge of the free-flowing road to cross the wider area required for the SPUI intersection below.{{Cn|date=October 2022}}

Because vehicles must be able to cross the pavement in six different ways, a SPUI generally has a very large area of uncontrolled pavement in the middle of the intersection. This can be unsafe particularly if drivers are unfamiliar with the interchange type. Drivers making a left turn may become confused as oncoming turning traffic passes them on the ''righthand'' side.{{Cn|date=October 2022}}

Due to the large intersection area, the traffic lights need a longer yellow and red phase to clear the intersection, and, even then, it may not be long enough for a bicyclist entering on green or yellow to make it across before opposing traffic gets a green.<ref name=bonneson/> In general, SPUI designs should not be used where bicycle traffic is expected unless fairly substantial changes to the design or special accommodations are provided.<ref name="kcbike.info">{{cite web |first1= Mohammad |last1= Qureshi |first2= Navin |last2= Sugathan |first3= Rohit |last3= Lasod |first4= Gary |last4= Spring |title= Design of Single Point Urban Interchanges, Research Investigation 02-015 |publisher= Missouri Department of Transportation Research, Development, and Technology, University of Missouri-Rolla |date= September 2004 |url= https://library.modot.mo.gov/RDT/reports/Ri02015/BrfApr05.pdf |access-date= February 10, 2010 |archive-date= May 30, 2010 |archive-url= https://web.archive.org/web/20100530115607/http://library.modot.mo.gov/RDT/reports/Ri02015/BrfApr05.pdf |url-status= live }}</ref>

Pedestrians are usually not able to get through the intersection with one green light. It can take up to four cycles to walk through the entire length of a SPUI.<ref name="kcbike.info"/>

Finally, SPUIs can be somewhat difficult to clear of snow. The large area in which lanes cross may have to be shut down to allow efficient and thorough cleaning lest a snowplow leave piles of snow, interfering with traffic and visibility in the middle of the uncontrolled pavement. Additionally, if the wide area of uncontrolled pavement is on a bridge, as in the diagram, the snow cannot be pushed to the sides of the bridge as it may pose a hazard to the road underneath. This problem can be exacerbated by the comparatively large bridge width required by the SPUI.

Given that a SPUI allows only left and right turns, drivers may not reenter the freeway they are departing (if, for example, they realize that they have taken the wrong exit) within a SPUI.

[[Traffic light#Rules|Three-phase traffic signals]] are required. Other interchange types designed for efficiency, such as the [[partial cloverleaf interchange#A4|six-ramp partial cloverleaf]] and the [[diverging diamond interchange|diverging diamond]], require just two signal phases.