THORNDON RAMP

Evening Post, Volume CXXIV, Issue 15, 17 July 1937, Page 10

THORNDON RAMP

TRAFFIC CONTROL

TURNS FROM HUTT ROAD

NEW LIGHT SYSTEM

The construction of the overbridge to connect the waterfront road with the Hutt Road is far enough ahead to

set motorists wondering—how are the bridge and its forked approaches to be used without one-half of the traffic getting in the way of the other half? It is a problem, and when all the regular lines of traffic over and under and! past the approaches are marked off on the plan it looks a greater puzzle than ever, for there are nine distinct lines of travel: up and down the Hutt Road; from the ramp to Petone and reverse; from the ramp to Thorndon Quay and reverse, and three other lanes that come in as side issues, but which have to be provided for, but the traffic lanes will sort themseles out simply enough under the guidance of a clever system of control lights. The approach to the overbndge will be forked at a point above the inner line of rail track so that one arm will slope down to road level on the seaward side of the road and the other will be carried across the roadway, supported by the central pier now being constructed, and slope down to the hill side of the roadway, which will be widened and later paved for some distance north of the centre pier; an excavator is digging away the bank for this widening below the railway^ houses on top of the bank. Straight-ahead traffic on the Hutt Road will continue as at present, except that its volume will be greatly reduced, by at least one half. Vehicles travelling from the Hutt Road to the waterfront road will keep to the left and take the seaward arm of the ramp, and those travelling from the waterfront towards Petone will keep to their'left and so come down to the Hutt Road by the hillside ramp. Those will be the main lanes, carryins something like 4000 cars, trucks, and buses in a ten-hour day. LIGHTS WILL SORT OUT THE TRAFFIC. The special control will be required for traffic, mostly in trucks and lorries, which will turn from Thorndon Quay on to the ramp to reach the waterfront, or which will be travelling from-the waterfront .to Thorndon Quay and the oil. and other stores on the Hutt Road. Such-traffic will cross the main flows of vehicles on a fairly short radius, necessitating the stopping of traffic in the main lanes to avoid danger of collision.

Most of the traffic which has come from Thorndon Quay will want to carry straight ahead towards Petone and only a fraction will be bound to the waterfront road, perhaps -in the proportions of ten to one, and as light control is to be used it looks like a fairly steep job to set any set of lights, unless main lane traffic is, to be delayed out of all proportion to real needs. Actually it will be a comparatively simple sorting out, proportioned very nearly to actual'requirements. The present proposal is that the lights should be actuated by contact pads, similar to those near the Queen's Wharf gates, where the traffic control is more effective than at any other controlled point in the city, but there will be addiional, "cancelling," pads.

Vehicles bound northward along the Hutt Road from Thorndon Quay will pass over a pad, which will operate a delayed action switch (electricians know how to do that sort of thing splendidly); if they are going straight ahead they will pass over a second pad which will make a contact which will cancel out the first, and so the main lanes will remain open. If a vehicle is to turn on to the ramp, the driver will pull up, the first contact will hold good, and the lights will change. A similar arrangement will operate for traffic coming off the ramp and intending to turn south to Thorndon Quay, or Tinakori Road.

The idea looks well on paper and similar installations are in operation overseas, but there are possibly "bugs" in it, and the Engineer's Office is making inquiries in, England as to details, and is seeking for suggestions which may be an improvement upon its plans, which are, of course, being sent to specialist manufacturers in detail, so that the proposad details may be considerably amended, though the principle will be about the same. LOOKING THEM OVER. It may be that the pad system may be discarded.. Pads were the very last word a year ago, but electrical appar-, atus moves rapidly from stage to stage I nowadays, and the last word (when the last engineering journals left England, so already it may have been superseded) in traffic control is the "electric eye," which looks traffic over ani makes its selection. The electric eye is in two units: one of them throws a narrow beam of light across the space to be controlled and the other is a hooded photo-electric cell which normally collects the beam of light. When the beam is interrupted the photo-electric cell notes the fact, and through a series of relays and contacts translates it into any sort of action that the .lectrician has decided on. These light-sensitive cells are used to open doors, catch burglars, light up street lamps, count football crowds or caramels; now they are beginning to control traffic, and a still later story is that they are being used to detect aeroplanes; but that does seem on the tall side.

| Whether pads or light-sensitive cells are used, according to the advice of the experts in England, the object will be the same, of sorting out traffic that wants to go straight ahead from that which wants to make a turn, but the celis would have the advantage that they could be easily shifted from one trial position to another, whereas a red pad is fixed as to position unless considerable additional expense is to be met.

The outlay will be fairly heavy, possibly over a thousand pounds, which would be unnecessary if the right- and left-hand turns could be avoided, but as Davis Street is to be closed to all vehicular traffic it would mean that the heavy haulage from the oil stores and warehouses on the Hutt Road and Thorndon Quay to the waterfront would have to be taken back via Bunny Street over distances of up to a mile, and apart from the extra running, that traffic -would jam up the railway station bottle-neck.'