A flyover or a flow under?

I was puzzled to read about the small flyover at Msida and I found it referred to the narrow slip road next to the roundabout, which was raised to allow flood waters to flow under it. In highway engineering, a flyover is a grade separated intersection allowing lines of traffic to flow over or under other flows of traffic, as at Portes des Bombes.

The Msida roundabout is the busiest traffic hub on the island and one messes about with it at one’s peril. Several factors including traffic intensity, topography, infrastructures, geology, meteorology, costs and disturbance involved make the design of a proper flyover there something of a nightmare.

In roundabouts, weaving of traffic streams is assumed and the more this is streamlined and rationalised the better. On the southern weaving arm, traffic coming mainly from Pietà has to choose between Guardamangia, Birkir­kara, Re­gional Road, Sliema and Gżira destinations. Practically none of this traffic would want to go to Valletta. On the northern weaving arm, the right turning traffic from the roundabout is joined by traffic from Birkirkara and the Regional Road wanting to go to Sliema, Gżira or Valletta.

Traffic lights can help to a certain extent but clearly delineated weaving paths should also be marked. Capacity is limited and I do not think we can afford to lose the extra capacity of the raised slip road, which also helps the weaving on the southern arm. Under certain weather conditions it is the only usable lane left.

I have not heard of many accidents, which would probably be minor ones, resulting from left turning traffic from this lane clashing with right turning traffic on the main roundabout. Probably, some regulation through give way signs is all that is called for.