The Gray & Houseman road construction vehicle, also known as a Highway Delva as well as a Highway Pathfinder, is a road construction vehicle that featured in End Of The Road.


At the front of the road construction vehicle is a door and retractable ramp used when the Gray & Houseman Explosives Truck needs to enter or exit the garage: the door rises and the ramp descends during these procedures. The garage has a turntable for trucks. At the bottom of the door are two lighting array troughs which contain spectrometers and ultrasound probes. On the roof next to the top of the door is a demolition gun, used in conjunction with the explosive truck to clear obstacles from its path. Behind the demolition gun is an armoured explosives magazine. On the other side of the explosives magazine is the reconnaissance helijet's maintenance hangar. Underneath the hangar is the road construction systems control room. Next to the control room is the bedrock distribution chamber. Further down the vehicle is a mineral store circulation pump, a tarmac storage tank, and a nuclear fusion reactor. The reactor provides power to vehicle turbines below and road construction machinery. Above is the crew accommodation deck with a canteen, recreation areas, and crew cabins. There is a lift which links the crew quarters to the office and control room. On the deck above is the control room and the Project Managers' office. On the far left side of this deck is the drivers' cabin. A communications array is on the roof of this top deck.

Main Control RoomEdit

The main control room sat at the very top of the machine (see cutaway drawing) and had adjoining offices for the Project Manager(Bob Gray). J.B Lester sits at his control desk, the Demolition Gun Operator can be seen at his controls (bottom right) and another operator can be seen in the background.


The main control room

Driving CrewEdit

The construction vehicle is driven by two engineers, whose cabin is situated up high on the right side of the vehicle.


In the front section of the vehicle is a huge garage, where the Explosives Truck was stowed. After re-entering the garage, the truck was rotated on a turntable to face forward, ready to leave again when needed.

Road Construction ProcessEdit

1. Spectrometers and ultrasound probes measure the ground's depth and composition.
2. Forward laser system vaporises the ground, which instantly excavates a channel.
3. Cahelium vacuum funnel takes in the vaporised soil and rock.
4. Cooling tubes pass vapour on to Reconstitution chamber.
5. Inside the Reconstitution chamber, the chemical structure of vapour is supplemented.
6. Supplemented vapour is then liquidised and adjoined to mineral store.
7. Secondary laser system cuts smooth sides of the channel.
8. Funnel spreads bedrock from the mineral store.
9. Pressure cylinder consolidates the bedrock down.
10. Funnel system spreads tarmac substitute from its storage tank.
11. Supercooled roller consolidates the tarmac.
12. Airjet cools the tarmac.
13. Paint tanks provide spray jet markers with heat-resistant paint for road markings.
14. Secondary cooling system establishes that the tarmac is ready for use almost instantaneously.

Scout HelijetEdit

The vehicle also carried a scout helijet.

Main article: Gray & Houseman Helijet

Cross-sections (Cutaway Drawings)Edit

To date, Graham Bleathman has produced three cutaway drawings of the construction vehicle.

  • The first appeared in a Thunderbirds Fleetway comic
  • The second appeared in a Thunderbirds Redan comic
  • And finally, the third featured in the 50th anniversary edition of the Haynes Thunderbirds manual


  • The model was adapted for use in Atlantic Inferno as the yellow Australian road-builder.