PA28 PLT DID NOT FOLLOW TWR INSTRUCTIONS FOR PATTERN ENTRY AT BED.

Narrative

A PIPER CHEROKEE 235; PLTED BY THE RPTR OF THIS SAFETY RPT; WAS CLRED TO ENTER A R DOWNWIND FOR RWY 23 AT BED; MA; BUT INSTEAD INADVERTENTLY INITIALLY SET UP FOR A L DOWNWIND. UPON INSISTENCE TO USE R DOWNWIND BY THE TWR CTLR; WHO APPEARED UNAWARE OF MY ACTUAL POS; I MADE AN UNINTENDED POOR DECISION TO CROSS IN FRONT OF DEPARTING TFC; ALONG THE UPWIND LEG. DEPARTING TFC; A PIPER WARRIOR; WAS CLOSE BUT NEVER ON A COLLISION COURSE AND WAS FULLY IN SIGHT AT ALL TIMES. THE SEQUENCE OF EVENTS IS DESCRIBED HERE. AT 9 MI SSW OF HANSCOM FIELD; HDG APPROX 030 DEGS; BOS APCH CTL CEASED RADAR SVCS AND ADVISED ME TO CONTACT HANSCOM TWR. DUE TO EXTREME CONGESTION ON THE TWR FREQ; THE INITIAL CALL TO HANSCOM TWR WAS MADE VERY BRIEF 'HANSCOM TWR; N-NUMBER; 7 MI SW; ATIS INFO.' TWR REPLIED; '...ENTER R DOWNWIND RWY 23.' AT THIS POINT; IN SPITE OF GREAT VISIBILITY AND CLR AFTERNOON SKIES; I COULD NOT SEE THE DEP END OF RWY 23. THE DEP END WAS OBSCURED BY TREES I WOULD LATER FIGURE OUT. I WAS NOT AWARE AT FIRST THAT I WAS ON THE L DOWNWIND SIDE OF THE EXTENDED CTRLINE. USING THE ARPT DIAGRAM OF THE TERMINAL PROC FOR ORIENTATION (REF 1) PROVIDED FURTHER CONFUSION AS I DID NOT REALIZE IMMEDIATELY THAT N IS NOT ALIGNED WITH THE TOP OF THE PAGE. IT IS ALIGNED TO THE L OF THE PAGE. THEREFORE; I EXPECTED TO SEE RWY 5/23 IN A DIFFERENT POS RELATIVE TO THE TWR AND TERMINAL BUILDING THAT WERE VISIBLE TO ME. I AM NOT VERY FAMILIAR WITH HANSCOM FIELD; HAVING BEEN THERE ONLY 3 OR 4 TIMES; ALWAYS UNDER IFR GUIDANCE TO THE RWY. NO TERRAIN FEATURES EXIST FOR ORIENTATION SW OF HANSCOM AS IT IS WOODED OVER A LARGE AREA. ADDITIONALLY; NO VOR OR ADF NAV IS PRESENT ON THE FIELD FOR DIRECTIONAL ORIENTATION. BUT A LARGE FACTOR IN ME NOT TURNING N EARLY ON TO ENTER THE TFC PATTERN OF RWY 23 FROM THE W ON R DOWNWIND WAS WORSE THAN EXPECTED PLT FATIGUE. FOR SEVERAL PRECEDING NIGHTS; MINIMAL SLEEP WAS HAD. THERE WAS PRESENT ENOUGH INFO; COMPASS HDG OF 030 DEGS; TO REALIZE THAT I WAS ON THE WRONG SIDE OF THE CTRLINE FOR R DOWNWIND. AT 3 MI FROM THE ARPT; STILL NOT ABLE TO SEE THE DEP END; I DID FIGURE OUT BASED ON HDG THAT I WAS ON THE WRONG SIDE OF THE CTRLINE TO ENTER R DOWNWIND. BUT NOW A STEADY STREAM OF DEPARTING ACFT PREVENTED THE TURN TO THE N. AND THE TWR FREQ WAS SO BUSY THAT I WAS UNABLE TO REQUEST A L DOWNWIND UNTIL ABOUT 1 MI FROM THE DEP END. THE TWR CTLR; NOT ANTICIPATING MY ACTUAL POS; INSISTED ON A R DOWNWIND AS PREVIOUSLY CLRED. AT THIS POINT I DETERMINED; IN HASTE; THAT I COULD SQUEEZE BTWN A DEPARTING C152 AND AN IN-TRAIL PIPER WARRIOR. A BETTER PLAN; GIVEN A MOMENT TO THINK ABOUT IT; WOULD HAVE BEEN TO DO A 180 DEG TURN OUT OF THE AREA OR JUST ENTER THE L DOWNWIND; THUS NOT REQUIRING A MANEUVER BTWN DEPARTING TFC. UNDERSTAND THOUGH THAT AT THAT MOMENT EITHER OF THOSE OPTIONS WOULD HAVE REQUIRED FURTHER PLT/CTLR INTERACTION ON ALREADY CONGESTED FREQ. THE REMAINDER OF THE LNDG WAS UNEVENTFUL BESIDE THE CONTINUED EXTREME FREQ CONGESTION. SEE THE ATTACHED DIAGRAM FOR FURTHER DETAIL. POSSIBLE CORRECTIVE ACTIONS; BESIDES HUMAN PERFORMANCE LESSONS WELL LEARNED BY THE RPTING PLT; ARE INCREASED CTLRS AND/OR AIRSPACE RESTRS AT EXTREMELY BUSY CLASS D ARPTS SUCH AT PAL-WAUKEE; TETERBORO; AND HANSCOM. I ALMOST CONSIDER THESE LOCATIONS TO BE UNSAFE ON CLR VFR DAYS AS THERE ARE SO MANY ACFT IN THE CLASS D AIRSPACE.