Tidal Flow Won’t Work

A tidal flow system for Wellington’s Terrace Tunnel has often been suggested (Letters, March 10-11) and, at first glance, seems a reasonable solution to traffic problems in the area. However, such a scheme was investigated in the late 1990s and showed that:

* The northbound traffic flow during the morning peak period (which has increased since then) well exceeded the capacity of a single traffic lane and that were a tidal flow system to be implemented, the result would be extensive traffic queues and congestion of most streets in the city’s south.

* Morning peak traffic queues and congestion could be better managed and with less disruption to the city and its roads if it occurred on the southbound motorway lanes approaching the tunnel.

Thus, a tidal flow system for the Terrace tunnel wasn’t considered viable.

The tunnel is the capacity restraint on the State Highway motorway section of the Ngauranga-Wellington airport corridor and it is running at capacity much of the time now. The airport corridor study might be able to suggest improvements for roading either side of it, but it’s extremely unlikely that any improvement can be made over the Terrace Tunnel section.

BRIAN ZEMANEK

Maungaraki

——————–

(c) 2007 Dominion Post. Provided by ProQuest Information and Learning. All rights Reserved.