[pierreh]

Major highway interchange reconstruction in Arcens.

Being at the center of the Talaran cluster, Arcens has a complex network of highways linking it to all other cities. This also entails several T-type interchanges, that originally were all constructed as parclos, and were all gradually changed into better interchanges, taking into account the flows of traffic between the various branches.

At the same time, some highways were widened, often from 4 lanes to 6 lanes, to account with the growth of the inter-city traffic. Alas, this was not carried out systematically, and some situations led to bottlenecks. In particular, the highway linking Arcens to Polsay in the south was only partially converted from 4 to 6 lanes; the portion close to the center of the city remained a 4-lane highway:



Also, the interchange between the central highway and the branch to Trelayne in the west was designed at a time where the main traffic was between the western and northern branches: that traffic could run on 2 lanes in each direction, all other flows could only use single lane (MIS) roadways. In addition, the 90 degree curve south of the interchange imposed limitations on ramps, leading to a somewhat unsatisfying design:



As the various cities grew, the patterns of the inter-city traffic changed. Eventually, the main traffic flow in the interchange became the north-south flow, that could only use one lane per direction, leading to a severe congestion:



It was decided to rebuild the entire interchange, with 2 lanes available for all flows. The portion of the highway to Polsay was to be upgraded from 4 to 6 lanes. It was also desired to destroy as few buildings as possible, although that turned out to be difficult. In a first stage, the old highway branches and ramps were all bulldozed to make room for the new construction:



The new interchange was then built, featuring again ramps on 3 levels but with a modified layout. One road and one avenue undergoround crossings had to be modified. A number of buildings (commercial buildings east of the interchange, residential ones on the west of it) had to be bulldozed, since the new interchange required more space; some new lots could be zoned. At the end of the construction the situation looked like this:



Since the new interchange was inaugurated, the city continued to grow, including on the newly zoned lots. The last picture in this post shows one residential and two commercial buildings under construction near the interchange:




The highway reconstruction program will continue in Arcens with the widening of the highway to Deramey in the east, from 4 to 6 lanes.