ifference was narrowing.

[Illustration: _Figure 4. Communications Systems of Bulgaria, 1973_]

_Table 2. Use of Transportation Facilities in Bulgaria, 1960 and 1970_

-------------------+-------------------------+-------------------------
| Total Freight* | Ton Miles**
Cargo Traffic: |------------+------------|------------+------------
| 1960 | 1970 | 1960 | 1970
-------------------+------------+------------+------------+------------
Railroads | 38.4 | 68.2 | 4,360 | 8,650
Motor transport | 128.3 | 492.8 | 1,270 | 4,940
Seaborne shipping | 1.1 | 14.5 | 1,530 | 24,375
Inland waterways | 1.6 | 3.7 | 384 | 1,145
Air transport | 0.007 | 0.083 | 0.2 | 9
-------------------+------------+------------+------------+------------

-------------------+-------------------------+-------------------------
| Total Passengers** | Passenger Miles**
Passenger Traffic: |-------------------------+------------+------------
| 1960 | 1970 | 1960 | 1970
-------------------+------------+------------+------------+------------
Railroads | 79.0 | 106.1 | 2,260 | 3,890
Motor transport | 72.6 | 282.0+ | 1,020 | 3,740+
Seaborne shipping | 0.6 | 0.6 | 12 | 17
Inland waterways | 0.8 | 0.3 | 29 | 19
Air transport | 0.2 | 1.1 | 56 | 750
-------------------+------------+------------+------------+------------
* In million tons.
** In millions.
+ 1969 information.
Source: Adapted from _Statistical Yearbook, 1971_, Sofia, 1971.

Conversion from steam to diesel and electric locomotives is proceeding
rapidly. As late as 1962 the country had no diesel locomotives and only
a few passenger-carrying electric trains. By 1972, about 80 percent of
the freight and a larger proportion of passenger traffic were carried on
diesel or electric trains. Steam locomotives will probably have been
replaced completely by 1978.

Roads

Construction is expensive, engineering problems are frequently
challenging, and the roads are difficult to maintain on the mountainous
terrain, with its many narrow and steep gorges. Ice and snow close most
routes at