Flood aftermath benefits speedometer development


No 157 in an informal history of buses in South Africa

 By Rollo Dickson

 The great flood of 1968 in Port Elizabeth –an unprecedented 355mm of rain fell within four hours on 1 September in the central area – had an important consequence for bus operation in the city. Locating alternative routings for services dislocated by road damage placed heavy demands on management initiative, the biggest difficulty being communication.

In the days following the flood, the general manager and his operating superintendent set out to patrol routes systematically – as far as these were usable – in their cars. They met back on Market Square every hour on the hour, comparing notes and gradually building up a picture of roads that could be used by rearranged bus services.

It was a slow and time-consuming business, continuing late into the night. In many cases, no alternative routing was available. South of the city centre, for instance, Summerstrand was cut off completely, the main road below the flooded Happy Valley having been washed out to sea.

Probably the most serious problem was the almost complete absence of telephone facilities. None of the company’s phones was working, leaving no means of contact between offices and depots. Effectively, the only usable phone was in the control inspector’s kiosk on Market Square – which explains why this point was chosen as the principal report-back rendezvous.

Main Street north of Market Square – the major bus route between the hill escarpment and the sea – resembled a vast swimming pool. Rainwater pouring down from higher ground had dammed up behind the newly-built north-south freeway.

It was to take many days to clear this accumulation, including the mass of debris that fouled the entire area.

The main railway traversing this zone was rendered totally inoperable. This heaped further responsibilities on the buses, which had to cater for the needs of train passengers as well.

Both suburban and main-line traffic was involved, with long-distance trains restricted to turning around outside the city. Buses had to be sent out to enable passengers to complete their journeys.

All this had to be accomplished in the absence of conventional means of communication inside the bus company as well as between the railways and P E Tramways.

With phone linkages badly affected, it quickly became obvious that some form of radio facility was urgently needed. Proposals were soon sought from reputable suppliers and orders placed.

Within months, every patrol car had been equipped with two-way radio, and every inspector responsible for despatching at busy terminals carried a walkie-talkie.

Considering that we are talking about the nineteen-sixties, the technology was still surprisingly primitive. Batteries especially were bulky and heavy, clumsy for carrying “portable” equipment.

The effect of the new radio technology was dramatic; soon nobody could imagine how matters had been managed without it.

At this time, the Port Elizabeth bus companies were all still part of the Cape Tramways group. The introduction of radio was so successful in operating terms that the sister concerns in Cape Town lost no time in following the example.

The use of radio brought a whole new dimension to the organisation, including the creating of a sophisticated backup workshop with full electronic repair facilities.

In due course, the technicians manning this department turned their attention to other areas of expertise. One of these concerned speed-measuring equipment.

The familiar mechanical speedometers had long proved costly and unreliable. Their proneness to failure was exacerbated by difficulties in obtaining spares.

It was by no means a new problem. For decades, urban buses – on the road continuously, day in and day out – were known for inoperative speedometers.

In Pretoria, to take one example, technicians gave up attempts to keep the equipment functioning. In the early fifties, a decision was taken to instal tachographs, and the whole municipal fleet, totalling nearly 300 vehicles, was equipped.

The tachographs indicated and recorded speed accurately. One recalls the International KB-7 petrol-engined single deckers, on which the tachographs, bolted to the modest dashboard, were clearly visible to passengers in the front seats.

When the limit of 35 miles per hour was reached, and a warning red light glowed , the driver would push the five-speed gear lever into fourth (which was otherwise never used). This effectively inhibited any greater momentum and kept the speed of the bus legal.

In the Cape Town radio workshop some decades later, a prototype, home-produced electronic speedometer gave promising results under test. It proved possible to manufacture an improved version in viable quantities. By the early nineteen eighties, some 90% of the fleet operated by all Tollgate Holdings’ subsidiary companies had been equipped with the innovative device.

The heart of the speedometer, a printed circuit board measuring 64mm x 45mm, is sourced from a local concern. The electronic components are soldered in the company workshop and connected to the indicating needle of a conventional rev counter – readily obtainable at low cost – from which unnecessary parts have been removed.

This is linked to the differential at the rear of the bus. A sensor, which transmits speed impulses and translates them into movement of the needle, reflects the speed at which the vehicle is travelling.

PE flood 1968: an unimaginable 355mm of rain fell within four hours in the central area.

Nearly 100 buses were marooned by floodwaters in Brickmakerskloof depot (seen in left foreground).

Temporary causeway at Happy Valley reconnected Summerstrand with the city.

One-year-old Guy single-decker in crater of collapsed roadway.

Pretoria City Transport 29-seat International KB-5, nineteen-fifties. The KB-7 was similar but had 35 seats.

Interior: Pretoria International.



The City Tramways company in Cape Town lost no time installing two-way radio, following the flood in Port Elizabeth. This was the control room in the nineteen-eighties.