Abstract: There is disclosed an aerial roadway comprised of prefabricated, cantilevered deck modules; and supporting columns, interlockingly mounted on and monolithically attached to prefabricated, prestressed, post-tensioned spinal beams supported on columns; an elevated roadway comprised of prefabricated cantilevered deck modules monolithically attached to a supporting wall; and a grade-level roadway comprised of deck modules monolithically attached to a foundation located at grade level. The deck modules are provided with integral layers of porous, bituminous paving material which provide a continuous, smooth, water-permeable running surface. Vehicles are directed along the aerial elevated and ground-level roadways by guide wheels depending from the vehicles and impinging on the guide beam fixed to the deck modules. A modification of the cantilevered deck modules provides aerial, elevated and ground-level roadways for transportation systems employing relatively small, light vehicles.

Abstract: A signal amplifier and clipper apparatus is disclosed including two four terminal capacitors and an operational amplifier to obtain fail-safe voltage gain which will not increase due to the failure of any element of the apparatus. A signal clipping operation is provided by the saturation of the operational amplifier output at the supply voltages, such that a maximum output signal level is provided by a fail-safe attenuator operation that will not decrease.

Abstract: A four quadrant analog by digital multiplier includes an amplifier gain network in which the digital sign bit controls the polarity of the gain of an amplifier to determine the product of the digital sign and the analog value, and in which the digital magnitude bits control a multiple of resistor steps of a resistance network to determine the product of the digital magnitude and analog value as previously multiplied by the digital sign bit in the amplifier gain network.

Abstract: A train vehicle zero speed sensing apparatus is provided for operation with a pair of tachometers coupled to the drive mechanism of a train vehicle, such that zero speed or an equivalent zero speed of the vehicle is sensed, and any single failure is detectable and will not yield a false zero speed indication.

Abstract: A signal bandpass filter apparatus is disclosed wherein a direct short circuit between input and output is prevented and the loss of the ground reference of the filter is detectable and fail-safe in operation.

Abstract: A high-reliability power amplifier employs passive automatic switching between parallel amplifier channels to provide a constant output power level, which is independent of the failure of an individual channel. The reliability of the amplifier network is improved by amplifying the input signal through parallel channels. Passive switching between channels and a constant level of power output are provided through a hybrid junction.

Abstract: A signal decoder is disclosed for use in a transportation vehicle control system in which vehicle control signal information bits are transmitted according to a multiple message frequency, FM, PSK, or FSK, comma-free binary coded command signal. The disclosed invention uses selective receiver channels for each command signal message frequency to detect information bits according to the selected message frequency. The detected information bits of each receiver channel are separately stored to comprise a separate information history for each message frequency and these information bit histories are then individually decoded. The decoded signals are compared to detect a discrepancy between any of the decoded signals due to component failures, signalling system noise, or component transient conditions. For any discrepancy between the decoded signals, a fail-safe comparator reduces the decoded signal to a more safe condition.

Abstract: The present invention relates to a train vehicle speed control signal providing apparatus operative with a frequency command speed control signal, and relates to the generation of the desired speed code signals in such a frequency rate system. Two separate and independent physical and electrical operations provide each of the respective desired frequency speed code signals in combination with a comparison step to provide an output speed code signal only if the two input frequency signals are each at the desired frequency.

Abstract: In a typical transportation vehicle control system, coded control information is transmitted to the transportation vehicles on vehicle command signals comprised of multiple message frequencies. A decoder is disclosed for decoding, in a fail-safe manner, information from message words which are comprised of message units carried on the multiple message frequencies. Vehicle speed command signals which are received by an antenna are amplified and frequencies which are substantially the same as the message frequencies are filtered from these signals. The filtered message frequencies are again amplified before message units are separately detected from each message frequency by a related filter-discriminator. The message units detected from a first message frequency by the related filter discriminator are delayed for the number of message units which comprise a message word. The message units detected from a second message frequency by the related filter-discriminator are inverted.

Abstract: A method and apparatus are disclosed for reducing effective inductance and providing balanced line-to-line voltages in induction machine dynamic braking circuits which utilize braking resistors to substantially increase the full torque braking range of the machine. The current phase lag caused by the inductive property of conventional braking resistors, is substantially reduced by rectifying the current provided to the braking resistor through a three-phase rectifier bridge. This reduction of the current phase lag permits a reduction in the capacitance required to compensate for the effective inductance in the dynamic braking circuit. Furthermore, because the braking currents flow through a common braking resistor, the line-to-line stator motor voltages are inherently balanced. If the prior art braking impedance control is also employed, the rectifier bridge need carry current only if dynamic braking is required when motor voltage is greater than the maximum voltage of the inverter supplying the machine.

Abstract: An antenna apparatus is disclosed for improved coupling of audio signals in relation to the vehicle track of a transit system operative with steel rails and providing a reduced cost for the associated hardware and lower crosstalk with adjacent signal blocks and track rails.

Abstract: An improved train vehicle speed control system is provided for operation in conjunction with train speed control signals and train occupancy indication signals in relation to a train vehicle track system including a plurality of predetermined track circuit signal blocks through which train vehicles pass. It is desired that a control of train vehicle speed be provided in relation to the detected occupancy by a train vehicle of a particular signal block, for maintaining train vehicle occupancy protection requirements and providing desired sequential occupancy control of the train vehicles through each of successive signal blocks through operation of provided protection signals with selected signal blocks behind the detected train vehicle. Spurious pseudo vehicle occupancy in a given signal block is detected and included in the provided train speed control in relation to that given signal block.

Abstract: An inverting amplifier apparatus is disclosed, which provides, in a failsafe manner, a predetermined initial gain that decreases linearly over a known range of frequencies. The disclosed inverting amplifier apparatus includes an amplifier whose feedback impedance contains a four terminal capacitor in parallel with a feedback resistor. The use of a four terminal capacitor as a feedback element makes the amplifier failsafe by preventing a failure mode of the amplifier in which the opening of the feedback element results in infinite AC gain of the amplifier. A virtual ground is provided at the junction of an input resistor, the feedback resistor, and one terminal of the four terminal capacitor, so the amplifier apparatus may simultaneously accommodate multiple input signals thereby permitting the amplifier apparatus to perform summing operations.

Abstract: In a transportation vehicle control system, a signal is detected from a transposed cable to determine the vehicle position relative to a predetermined speed control zone. This position data, along with other manual and/or automatic inputs, is fed into a profile function generator whose output is a predetermined singular function of the position and other inputs. While the vehicle is within the speed control zone, the output of the profile function generator is converted from digital form into analog form and then used to limit the vehicle speed.

Abstract: A receiver is disclosed which is used in a transportation vehicle detection system to compare logic conditions in signals which are transmitted from a first vehicle pathway location, with logic conditions which are detected from signals received at a second vehicle pathway location. When first and second enable signals correspond, the signal from an oscillator is transmitted through two pairs of fail-safe AND gates and applied, through a fail-safe OR gate, to a latch circuit which signals the transportation system speed controller that no vehicle is present between the first and second pathway locations. When the first and second enable signals do not correspond, the signal from the oscillator is not transmitted through both pairs of fail-safe AND gates, there is no signal applied to the fail-safe OR gate, and no signal is applied to the latch circuit which signals the transportation system speed controller that a vehicle is present between the first and second pathway locations.

Abstract: There is disclosed an input signal threshold responsive apparatus for responding to a predetermined input signal energy level, in relation to a voltage and time product, before an associated train vehicle control system is enabled by a provided gated enable signal. The provided apparatus responds to one of a plurality of input signals, having respectively different frequencies and different amplitudes, and provides an enabling output signal.It is desired to provide an improved threshold sensitive input signal receiver apparatus in conjunction with train vehicle control and in relation to plural stray signals in a given track circuit signal block due to cross talk from adjacent signal blocks and the like. The input signal responsive or sensitivity threshold is established in relation to the practical required signal level of the desired signal to be received within the given signal block.

Abstract: An improved train vehicle speed control system is provided for operation in conjunction with train vehicle occupancy control signals and train occupancy indication signals in relation to a train vehicle track system including a plurality of predetermined track circuit signal blocks through which the train vehicles pass. It is desired that control of train vehicle speed be provided in relation to the detected occupancy by the train vehicle in a particular signal block, for maintaining train vehicle occupancy protection requirements and providing protection signals to establish desired sequential occupancy control of the train vehicles through each of selected signal blocks adjacent to that particular signal block. Spurious pseudo vehicle occupancy in any signal block is detected and included in the provided train speed control in relation to that signal block.

Abstract: There is disclosed a train vehicle protection apparatus including the determination of train vehicle occupancy of a track circuit signal block, wherein a frequency tone speed code signal is provided to the signal block for controlling the train vehicle speed and a vital and fail-safe determination of train vehicle occupancy of the signal block is provided.

Abstract: A signal transmitter provides an oscillatory signal to an antenna situated along a vehicle stopping area. The antenna has incremental transpositions along its length for reversing the phase of the magnetic field produced at each transposition in response to the provision of the oscillatory signal. Signal receiving means on a vehicle sense the phase reversals of the magnetic field, and when the phase reversals are sensed at a rate proportional to a defined zero speed of the vehicle, at least one door on the vehicle is opened.

Abstract: An antenna apparatus is disclosed for coupling audio frequency signals in relation to one or more vehicle track rails of a transit system for the purpose of determining vehicle occupancy of a given signal block and providing speed coded control signals to a vehicle moving along the track rail in that given signal block. It is desired that each signal block in the transit system track circuit operate with the signal level above a predetermined minimum signal level for reasons of vehicle occupational detection. The antenna apparatus is operative to enable desired adjustment of the signal level in a given signal block and in adjacent signal blocks relative to that given signal block.