Help me finish my PCB design.

We are a small team helping to develop a product that will be installed primarily on school busses to help deter people from passing a stopped bus. I have designed a simple circuit that provides 2 functions. 1. An alternating light flasher, this was done using 2 555 timers. 2. A motor control, Forward when the circuit is on, reverse when it turns off. The whole thing is pretty simple. and is currently functioning just fine in our lab. But thats the problem, it functions just fine in our lab, I need to ensure that this circuit (which has proven to be sensitive to voltage fluctuations) can operate correctly in the electrically noisy environment that is a school bus. So here is the scope of what were looking for; 1. Add whatever is necessary to the 12VDC input to ensure that the circuit is getting clean voltage. Again this will be installed in a school bus, so its a very noisy and fluctuating environment. 2. There is a relay that controls the direction of the motor output, I would like to add an adjustable boost converter before this relay so that the voltage to the motor can be increased so that we can adjust the speed of the motor. 3. The PCB traces that go to the lights and the motor must be sized to handle the load on them. 4. General cleanup of the routing to ease production costs. This should be a quick and simple project. I just don't have enough confidence in my limited knowledge of PCB design and circuits to put this out into the field as is. I currently have the design in PCB123 format so you will need to download a free copy from sunstone circuits in order to open the file. But the PCB123 file should contain all the components I have used in the current design except the relays which I included on the attachment, and the LEDS which are just standard through hole 12V LEDS. When all is said and done I would like to have the completed design either in PCB123 or regular gerber files with a schematic that I can send out for production. I also need a list of all the components used so that I know what to purchase when we go to assemble the boards.